Quantum dot

Short description: Zero-dimensional, nano-scale semiconductor particles with novel optical and electronic properties

Colloidal quantum dots irradiated with a UV light. Different sized quantum dots emit different colors of light due to quantum confinement.

Part of a series of articles on

Nanomaterials
Carbon nanotubes

* Synthesis
* Chemistry
* Mechanical properties
* Optical properties
* Applications
* Timeline

Fullerenes

* Buckminsterfullerene
* C70 fullerene
* Chemistry
* Health impact
* Carbon allotropes

Other nanoparticles

* Quantum dots
* Aluminium oxide
* Cellulose
* Ceramic
* Cobalt oxide
* Copper
* Gold
* Iron
* Iron oxide
* Iron–platinum
* Lipid
* Platinum
* Silver
* Titanium dioxide

Nanostructured materials

* Nanocomposite
* Nanofoam
* Nanoporous materials
* Nanocrystalline material

*   *

* v
* t
* e

Quantum dots (QDs) - also called semiconductor nanocrystals, are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology and materials science. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band. The excited electron can drop back into the valence band releasing its energy as light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the conductance band and the valence band, or the transition between discrete energy states when the band structure is no longer well-defined in QDs.

Nanoscale semiconductor materials tightly confine either electrons or electron holes. The confinement is similar to a three-dimensional particle in a box model. The quantum dot absorption and emission features correspond to transitions between discrete quantum mechanically allowed energy levels in the box that are reminiscent of atomic spectra. For these reasons, quantum dots are sometimes referred to as artificial atoms,[1] emphasizing their bound and discrete electronic states, like naturally occurring atoms or molecules.[2][3] It was shown that the electronic wave functions in quantum dots resemble the ones in real atoms.[4] By coupling two or more such quantum dots, an artificial molecule can be made, exhibiting hybridization even at room temperature.[5] Precise assembly of quantum dots can form superlattices that act as artificial solid-state materials that exhibit unique optical and electronic properties.[6][7]

Quantum dots have properties intermediate between bulk semiconductors and discrete atoms or molecules. Their optoelectronic properties change as a function of both size and shape.[8][9] Larger QDs of 5–6 nm diameter emit longer wavelengths, with colors such as orange, or red. Smaller QDs (2–3 nm) emit shorter wavelengths, yielding colors like blue and green. However, the specific colors vary depending on the exact composition of the QD.[10]

Potential applications of quantum dots include single-electron transistors, solar cells, LEDs, lasers,[11] single-photon sources,[12][13][14] second-harmonic generation, quantum computing,[15] cell biology research,[16] microscopy,[17] and medical imaging.[18] Their small size allows for some QDs to be suspended in solution, which may lead to their use in inkjet printing, and spin coating.[19] They have been used in Langmuir-Blodgett thin films.[20][21][22] These processing techniques result in less expensive and less time-consuming methods of semiconductor fabrication.

## Contents

* 1 Production
* 1.1 Colloidal synthesis
* 1.2 Plasma synthesis
* 1.3 Fabrication
* 1.4 Viral assembly
* 1.5 Electrochemical assembly
* 1.6 Bulk-manufacture
* 1.7 Heavy-metal-free quantum dots
* 2 Health and safety
* 3 Optical properties
* 4 Applications
* 4.1 Subcutaneous record-keeping
* 4.2 Biology
* 4.3 Photovoltaic devices
* 4.3.1 Quantum dot only solar cells
* 4.3.2 Quantum dot in hybrid solar cells
* 4.3.3 Quantum dot with nanowire in solar cells
* 4.4 Light emitting diodes
* 4.5 Quantum dot displays
* 4.6 Photodetector devices
* 4.7 Photocatalysts
* 5 Theory
* 6 Quantum confinement in semiconductors
* 6.1 Models
* 6.2 Quantum mechanics
* 6.2.1 Semiclassical
* 6.2.2 Classical mechanics
* 7 History
* 8 See also
* 9 References
* 10 Further reading
* 11 External links

## Production

Quantum Dots with gradually stepping emission from violet to deep red

There are several ways to fabricate quantum dots. Possible methods include colloidal synthesis, self-assembly, and electrical gating.

### Colloidal synthesis

Colloidal semiconductor nanocrystals are synthesized from solutions, much like traditional chemical processes. The main difference is the product neither precipitates as a bulk solid nor remains dissolved.[8] Heating the solution at high temperature, the precursors decompose forming monomers which then nucleate and generate nanocrystals. Temperature is a critical factor in determining optimal conditions for the nanocrystal growth. It must be high enough to allow for rearrangement and annealing of atoms during the synthesis process while being low enough to promote crystal growth. The concentration of monomers is another critical factor that has to be stringently controlled during nanocrystal growth. The growth process of nanocrystals can occur in two different regimes: "focusing" and "defocusing". At high monomer concentrations, the critical size (the size where nanocrystals neither grow nor shrink) is relatively small, resulting in growth of nearly all particles. In this regime, smaller particles grow faster than large ones (since larger crystals need more atoms to grow than small crystals) resulting in the size distribution focusing, yielding an improbable distribution of nearly monodispersed particles. The size focusing is optimal when the monomer concentration is kept such that the average nanocrystal size present is always slightly larger than the critical size. Over time, the monomer concentration diminishes, the critical size becomes larger than the average size present, and the distribution defocuses.

Cadmium sulfide quantum dots on cells

There are colloidal methods to produce many different semiconductors. Typical dots are made of binary compounds such as lead sulfide, lead selenide, cadmium selenide, cadmium sulfide, cadmium telluride, indium arsenide, and indium phosphide. Dots may also be made from ternary compounds such as cadmium selenide sulfide. Further, recent advances have been made which allow for synthesis of colloidal perovskite quantum dots.[23] These quantum dots can contain as few as 100 to 100,000 atoms within the quantum dot volume, with a diameter of ≈10 to 50 atoms. This corresponds to about 2 to 10 nanometers, and at 10 nm in diameter, nearly 3 million quantum dots could be lined up end to end and fit within the width of a human thumb.

Idealized image of colloidal nanoparticle of lead sulfide (selenide) with complete passivation by oleic acid, oleyl amine, and hydroxyl ligands (size ≈5nm)

Large batches of quantum dots may be synthesized via colloidal synthesis. Due to this scalability and the convenience of benchtop conditions, colloidal synthetic methods are promising for commercial applications.

### Plasma synthesis

Plasma synthesis has evolved to be one of the most popular gas-phase approaches for the production of quantum dots, especially those with covalent bonds.[24][25][26] For example, silicon (Si) and germanium (Ge) quantum dots have been synthesized by using nonthermal plasma. The size, shape, surface and composition of quantum dots can all be controlled in nonthermal plasma.[27][28] Doping that seems quite challenging for quantum dots has also been realized in plasma synthesis.[29][30][31] Quantum dots synthesized by plasma are usually in the form of powder, for which surface modification may be carried out. This can lead to excellent dispersion of quantum dots in either organic solvents[32] or water[33] (i. e., colloidal quantum dots).

### Fabrication

The electrostatic potential needed to create a quantum dot can be realized with several methods. These include external electrodes,[34] doping, strain,[35] or impurities. Self-assembled quantum dots are typically between 5 and 50 nm in size. Quantum dots defined by lithographically patterned gate electrodes, or by etching on two-dimensional electron gases in semiconductor heterostructures can have lateral dimensions between 20 and 100 nm.

* Some quantum dots are small regions of one material buried in another with a larger band gap. These can be so-called core–shell structures, e.g., with CdSe in the core and ZnS in the shell, or from special forms of silica called ormosil. Sub-monolayer shells can also be effective ways of passivating the quantum dots, such as PbS cores with sub-monolayer CdS shells.[36]
* Quantum dots sometimes occur spontaneously in quantum well structures due to monolayer fluctuations in the well's thickness.

Atomic resolution scanning transmission electron microscopy image of an indium gallium arsenide (InGaAs) quantum dot buried in gallium arsenide (GaAs)

* Self-assembled quantum dots nucleate spontaneously under certain conditions during molecular beam epitaxy (MBE) and metalorganic vapour-phase epitaxy (MOVPE), when a material is grown on a substrate to which it is not lattice matched. The resulting strain leads to the formation of islands on top of a two-dimensional wetting layer. This growth mode is known as Stranski–Krastanov growth.[37] The islands can be subsequently buried to form the quantum dot. A widely used type of quantum dots grown with this method are indium gallium arsenide (InGaAs) quantum dots in gallium arsenide (GaAs).[38] Such quantum dots have the potential for applications in quantum cryptography (i.e. single-photon sources) and quantum computation. The main limitations of this method are the cost of fabrication and the lack of control over positioning of individual dots.
* Individual quantum dots can be created from two-dimensional electron or hole gases present in remotely doped quantum wells or semiconductor heterostructures called lateral quantum dots. The sample surface is coated with a thin layer of resist and a lateral pattern is then defined in the resist by electron beam lithography. This pattern can then be transferred to the electron or hole gas by etching, or by depositing metal electrodes (lift-off process) that allow the application of external voltages between the electron gas and the electrodes. Such quantum dots are mainly of interest for experiments and applications involving electron or hole transport and they are also used as spin qubits.[39] A strength of this type of quantum dots is that their energy spectrum can be engineered by controlling the geometrical size, shape, and the strength of the confinement potential with gate electrodes. These quantum dots can be easily connected by tunnel barriers to conducting leads, which allows the application of the techniques of tunneling spectroscopy for their investigation.
* Complementary metal–oxide–semiconductor (CMOS) technology can be employed to fabricate silicon quantum dots. Ultra small (L=20 nm, W=20 nm) CMOS transistors behave as single electron quantum dots when operated at cryogenic temperature over a range of −269 °C (4 K) to about −258 °C (15 K). The transistor displays Coulomb blockade due to progressive charging of electrons (holes) one by one. The number of electrons (holes) confined in the channel is driven by the gate voltage, starting from an occupation of zero electrons (holes), and it can be set to 1 or many.[40]

### Viral assembly

Genetically engineered M13 bacteriophage viruses allow preparation of quantum dot biocomposite structures.[41] It had previously been shown that genetically engineered viruses can recognize specific semiconductor surfaces through the method of selection by combinatorial phage display.[42] Additionally, it is known that liquid crystalline structures of wild-type viruses (Fd, M13, and TMV) are adjustable by controlling the solution concentrations, solution ionic strength, and the external magnetic field applied to the solutions. Consequently, the specific recognition properties of the virus can be used to organize inorganic nanocrystals, forming ordered arrays over the length scale defined by liquid crystal formation. Using this information, Lee et al. (2000) were able to create self-assembled, highly oriented, self-supporting films from a phage and ZnS precursor solution. This system allowed them to vary both the length of bacteriophage and the type of inorganic material through genetic modification and selection.

### Electrochemical assembly

Highly ordered arrays of quantum dots may also be self-assembled by electrochemical techniques. A template is created by causing an ionic reaction at an electrolyte-metal interface which results in the spontaneous assembly of nanostructures, including quantum dots, onto the metal which is then used as a mask for mesa-etching these nanostructures on a chosen substrate.[citation needed]

### Bulk-manufacture

Quantum dot manufacturing relies on a process called high temperature dual injection which has been scaled by multiple companies for commercial applications that require large quantities (hundreds of kilograms to tons) of quantum dots. This reproducible production method can be applied to a wide range of quantum dot sizes and compositions.

The bonding in certain cadmium-free quantum dots, such as III-V-based quantum dots, is more covalent than that in II-VI materials, therefore it is more difficult to separate nanoparticle nucleation and growth via a high temperature dual injection synthesis. An alternative method of quantum dot synthesis, the molecular seeding process, provides a reproducible route to the production of high-quality quantum dots in large volumes. The process utilises identical molecules of a molecular cluster compound as the nucleation sites for nanoparticle growth, thus avoiding the need for a high temperature injection step. Particle growth is maintained by the periodic addition of precursors at moderate temperatures until the desired particle size is reached.[43] The molecular seeding process is not limited to the production of cadmium-free quantum dots; for example, the process can be used to synthesise kilogram batches of high-quality II-VI quantum dots in just a few hours.

Another approach for the mass production of colloidal quantum dots can be seen in the transfer of the well-known hot-injection methodology for the synthesis to a technical continuous flow system. The batch-to-batch variations arising from the needs during the mentioned methodology can be overcome by utilizing technical components for mixing and growth as well as transport and temperature adjustments. For the production of CdSe based semiconductor nanoparticles this method has been investigated and tuned to production amounts of kg per month. Since the use of technical components allows for easy interchange in regards of maximum throughput and size, it can be further enhanced to tens or even hundreds of kilograms.[44]

In 2011 a consortium of U.S. and Dutch companies reported a milestone in high volume quantum dot manufacturing by applying the traditional high temperature dual injection method to a flow system.[45]

On 23 January 2013 Dow entered into an exclusive licensing agreement with UK-based Nanoco for the use of their low-temperature molecular seeding method for bulk manufacture of cadmium-free quantum dots for electronic displays, and on 24 September 2014 Dow commenced work on the production facility in South Korea capable of producing sufficient quantum dots for "millions of cadmium-free televisions and other devices, such as tablets". Mass production is due to commence in mid-2015.[46] On 24 March 2015 Dow announced a partnership deal with LG Electronics to develop the use of cadmium free quantum dots in displays.[47]

### Heavy-metal-free quantum dots

In many[which?] regions of the world there is now a restriction or ban on the use of toxic heavy metals in many household goods, which means that most cadmium-based quantum dots are unusable for consumer-goods applications.

For commercial viability, a range of restricted, heavy-metal-free quantum dots has been developed showing bright emissions in the visible and near-infrared region of the spectrum and have similar optical properties to those of CdSe quantum dots. Among these materials are InP/ZnS, CuInS/ZnS, Si, Ge, and C.

Peptides are being researched as potential quantum dot material.[48]

## Health and safety

Main pages: Physics:Health and safety hazards of nanomaterials and Chemistry:Nanotoxicology

Some quantum dots pose risks to human health and the environment under certain conditions.[49][50][51] Notably, the studies on quantum dot toxicity have focused on particles containing cadmium and have yet to be demonstrated in animal models after physiologically relevant dosing.[51] In vitro studies, based on cell cultures, on quantum dots (QD) toxicity suggest that their toxicity may derive from multiple factors including their physicochemical characteristics (size, shape, composition, surface functional groups, and surface charges) and their environment. Assessing their potential toxicity is complex as these factors include properties such as QD size, charge, concentration, chemical composition, capping ligands, and also on their oxidative, mechanical, and photolytic stability.[49]

Many studies have focused on the mechanism of QD cytotoxicity using model cell cultures. It has been demonstrated that after exposure to ultraviolet radiation or oxidation by air, CdSe QDs release free cadmium ions causing cell death.[52] Group II–VI QDs also have been reported to induce the formation of reactive oxygen species after exposure to light, which in turn can damage cellular components such as proteins, lipids, and DNA.[53] Some studies have also demonstrated that addition of a ZnS shell inhibits the process of reactive oxygen species in CdSe QDs. Another aspect of QD toxicity is that there are, in vivo, size-dependent intracellular pathways that concentrate these particles in cellular organelles that are inaccessible by metal ions, which may result in unique patterns of cytotoxicity compared to their constituent metal ions.[54] The reports of QD localization in the cell nucleus[55] present additional modes of toxicity because they may induce DNA mutation, which in turn will propagate through future generation of cells, causing diseases.

Although concentration of QDs in certain organelles have been reported in in vivo studies using animal models, no alterations in animal behavior, weight, hematological markers, or organ damage has been found through either histological or biochemical analysis.[56] These findings have led scientists to believe that intracellular dose is the most important determining factor for QD toxicity. Therefore, factors determining the QD endocytosis that determine the effective intracellular concentration, such as QD size, shape, and surface chemistry determine their toxicity. Excretion of QDs through urine in animal models also have demonstrated via injecting radio-labeled ZnS-capped CdSe QDs where the ligand shell was labeled with 99mTc.[57] Though multiple other studies have concluded retention of QDs in cellular levels,[51][58] exocytosis of QDs is still poorly studied in the literature.

While significant research efforts have broadened the understanding of toxicity of QDs, there are large discrepancies in the literature, and questions still remain to be answered. Diversity of this class of material as compared to normal chemical substances makes the assessment of their toxicity very challenging. As their toxicity may also be dynamic depending on the environmental factors such as pH level, light exposure, and cell type, traditional methods of assessing toxicity of chemicals such as LD50 are not applicable for QDs. Therefore, researchers are focusing on introducing novel approaches and adapting existing methods to include this unique class of materials.[51] Furthermore, novel strategies to engineer safer QDs are still under exploration by the scientific community. A recent novelty in the field is the discovery of carbon quantum dots, a new generation of optically-active nanoparticles potentially capable of replacing semiconductor QDs, but with the advantage of much lower toxicity.

## Optical properties

Fluorescence spectra of CdTe quantum dots of various sizes. Different sized quantum dots emit different color light due to quantum confinement.

In semiconductors, light absorption generally leads to an electron being excited from the valence to the conduction band, leaving behind a hole. The electron and the hole can bind to each other to form an exciton. When this exciton recombines (i.e. the electron resumes its ground state), the exciton's energy can be emitted as light. This is called fluorescence. In a simplified model, the energy of the emitted photon can be understood as the sum of the band gap energy between the highest occupied level and the lowest unoccupied energy level, the confinement energies of the hole and the excited electron, and the bound energy of the exciton (the electron–hole pair):

As the confinement energy depends on the quantum dot's size, both absorption onset and fluorescence emission can be tuned by changing the size of the quantum dot during its synthesis. The larger the dot, the redder (lower-energy) its absorption onset and fluorescence spectrum. Conversely, smaller dots absorb and emit bluer (higher-energy) light. Recent articles suggest that the shape of the quantum dot may be a factor in the coloration as well, but as yet not enough information is available [citation needed]. Furthermore, it was shown[59] that the lifetime of fluorescence is determined by the size of the quantum dot. Larger dots have more closely spaced energy levels in which the electron–hole pair can be trapped. Therefore, electron–hole pairs in larger dots live longer causing larger dots to show a longer lifetime.

To improve fluorescence quantum yield, quantum dots can be made with shells of a larger bandgap semiconductor material around them. The improvement is suggested to be due to the reduced access of electron and hole to non-radiative surface recombination pathways in some cases, but also due to reduced Auger recombination in others.

## Applications

Quantum dots are particularly promising for optical applications due to their high extinction coefficient[60] and ultrafast optical nonlinearities with potential applications for developing all-optical systems.[61] They operate like a single-electron transistor and show the Coulomb blockade effect. Quantum dots have also been suggested as implementations of qubits for quantum information processing,[62] and as active elements for thermoelectrics.[63][64][65]

Tuning the size of quantum dots is attractive for many potential applications. For instance, larger quantum dots have a greater spectrum-shift toward red compared to smaller dots and exhibit less pronounced quantum properties. Conversely, the smaller particles allow one to take advantage of more subtle quantum effects.

A device that produces visible light, through energy transfer from thin layers of quantum wells to crystals above the layers.[66]

Being zero-dimensional, quantum dots have a sharper density of states than higher-dimensional structures. As a result, they have superior transport and optical properties. They have potential uses in diode lasers, amplifiers, and biological sensors.[67] Quantum dots may be excited within a locally enhanced electromagnetic field produced by gold nanoparticles, which then can be observed from the surface plasmon resonance in the photoluminescent excitation spectrum of (CdSe)ZnS nanocrystals. High-quality quantum dots are well suited for optical encoding and multiplexing applications due to their broad excitation profiles and narrow/symmetric emission spectra. The new generations of quantum dots have far-reaching potential for the study of intracellular processes at the single-molecule level, high-resolution cellular imaging, long-term in vivo observation of cell trafficking, tumor targeting, and diagnostics.

CdSe nanocrystals are efficient triplet photosensitizers.[68] Laser excitation of small CdSe nanoparticles enables the extraction of the excited state energy from the quantum dots into bulk solution, thus opening the door to a wide range of potential applications such as photodynamic therapy, photovoltaic devices, molecular electronics, and catalysis.

### Subcutaneous record-keeping

In December 2019, Robert S. Langer and his team developed and patented a technique whereby transdermal patches could be used to apply an identification tattoo to people with invisible ink to store information subcutaneously. This was presented as a boon to "developing nations" where lack of infrastructure means an absence of medical records.[69][70] The technology, which is assigned to the Massachusetts Institute of Technology,[70] uses a "quantum dot dye that is delivered, in this case along with a vaccine, by a microneedle patch." The research "was funded by the Bill and Melinda Gates Foundation and the Koch Institute for Integrative Cancer Research."[69]

### Biology

In modern biological analysis, various kinds of organic dyes are used. However, as technology advances, greater flexibility in these dyes is sought.[71] To this end, quantum dots have quickly filled in the role, being found to be superior to traditional organic dyes on several counts, one of the most immediately obvious being brightness (owing to the high extinction coefficient combined with a comparable quantum yield to fluorescent dyes[16]) as well as their stability (allowing much less photobleaching).[72] It has been estimated that quantum dots are 20 times brighter and 100 times more stable than traditional fluorescent reporters.[71] For single-particle tracking, the irregular blinking of quantum dots is a minor drawback. However, there have been groups which have developed quantum dots which are essentially nonblinking and demonstrated their utility in single-molecule tracking experiments.[73][74]

The use of quantum dots for highly sensitive cellular imaging has seen major advances.[75] The improved photostability of quantum dots, for example, allows the acquisition of many consecutive focal-plane images that can be reconstructed into a high-resolution three-dimensional image.[76] Another application that takes advantage of the extraordinary photostability of quantum dot probes is the real-time tracking of molecules and cells over extended periods of time.[77] Antibodies, streptavidin,[78] peptides,[79] DNA,[80] nucleic acid aptamers,[81] or small-molecule ligands[82] can be used to target quantum dots to specific proteins on cells. Researchers were able to observe quantum dots in lymph nodes of mice for more than 4 months.[83]

Quantum dots can have antibacterial properties similar to nanoparticles and can kill bacteria in a dose-dependent manner.[84] One mechanism by which quantum dots can kill bacteria is through impairing the functions of antioxidative system in the cells and down regulating the antioxidative genes. In addition, quantum dots can directly damage the cell wall. Quantum dots have been shown to be effective against both gram- positive and gram-negative bacteria.[85]

Semiconductor quantum dots have also been employed for in vitro imaging of pre-labeled cells. The ability to image single-cell migration in real time is expected to be important to several research areas such as embryogenesis, cancer metastasis, stem cell therapeutics, and lymphocyte immunology.

One application of quantum dots in biology is as donor fluorophores in Förster resonance energy transfer, where the large extinction coefficient and spectral purity of these fluorophores make them superior to molecular fluorophores[86] It is also worth noting that the broad absorbance of QDs allows selective excitation of the QD donor and a minimum excitation of a dye acceptor in FRET-based studies.[87] The applicability of the FRET model, which assumes that the Quantum Dot can be approximated as a point dipole, has recently been demonstrated[88]

The use of quantum dots for tumor targeting under in vivo conditions employ two targeting schemes: active targeting and passive targeting. In the case of active targeting, quantum dots are functionalized with tumor-specific binding sites to selectively bind to tumor cells. Passive targeting uses the enhanced permeation and retention of tumor cells for the delivery of quantum dot probes. Fast-growing tumor cells typically have more permeable membranes than healthy cells, allowing the leakage of small nanoparticles into the cell body. Moreover, tumor cells lack an effective lymphatic drainage system, which leads to subsequent nanoparticle-accumulation.

Quantum dot probes exhibit in vivo toxicity. For example, CdSe nanocrystals are highly toxic to cultured cells under UV illumination, because the particles dissolve, in a process known as photolysis, to release toxic cadmium ions into the culture medium. In the absence of UV irradiation, however, quantum dots with a stable polymer coating have been found to be essentially nontoxic.[83][50] Hydrogel encapsulation of quantum dots allows for quantum dots to be introduced into a stable aqueous solution, reducing the possibility of cadmium leakage. Then again, only little is known about the excretion process of quantum dots from living organisms.[89]

In another potential application, quantum dots are being investigated as the inorganic fluorophore for intra-operative detection of tumors using fluorescence spectroscopy.

Delivery of undamaged quantum dots to the cell cytoplasm has been a challenge with existing techniques. Vector-based methods have resulted in aggregation and endosomal sequestration of quantum dots while electroporation can damage the semi-conducting particles and aggregate delivered dots in the cytosol. Via cell squeezing, quantum dots can be efficiently delivered without inducing aggregation, trapping material in endosomes, or significant loss of cell viability. Moreover, it has shown that individual quantum dots delivered by this approach are detectable in the cell cytosol, thus illustrating the potential of this technique for single-molecule tracking studies.[90]

### Photovoltaic devices

Main page: Physics:Quantum dot solar cell

The tunable absorption spectrum and high extinction coefficients of quantum dots make them attractive for light harvesting technologies such as photovoltaics. Quantum dots may be able to increase the efficiency and reduce the cost of today's typical silicon photovoltaic cells. According to an experimental report from 2004,[91] quantum dots of lead selenide (PbSe) can produce more than one exciton from one high-energy photon via the process of carrier multiplication or multiple exciton generation (MEG). This compares favorably to today's photovoltaic cells which can only manage one exciton per high-energy photon, with high kinetic energy carriers losing their energy as heat. On the other hand, the quantum-confined ground-states of colloidal quantum dots (e.g. lead sulfide, PbS) incorporated in wider-bandgap host semiconductors (e.g. perovskite) can allow the generation of photocurrent from photons with energy below the host bandgap, via a two-photon absorption process, offering another approach (termed intermediate band, IB) to exploit a broader range of the solar spectrum and thereby achieve higher photovoltaic efficiency.[92][93]

Colloidal quantum dot photovoltaics would theoretically be cheaper to manufacture, as they can be made using simple chemical reactions.

#### Quantum dot only solar cells

Aromatic self-assembled monolayers (SAMs) (e.g. 4-nitrobenzoic acid) can be used to improve the band alignment at electrodes for better efficiencies. This technique has provided a record power conversion efficiency (PCE) of 10.7%.[94] The SAM is positioned between ZnO-PbS colloidal quantum dot (CQD) film junction to modify band alignment via the dipole moment of the constituent SAM molecule, and the band tuning may be modified via the density, dipole and the orientation of the SAM molecule.[94]

#### Quantum dot in hybrid solar cells

Colloidal quantum dots are also used in inorganic/organic hybrid solar cells. These solar cells are attractive because of the potential for low-cost fabrication and relatively high efficiency.[95] Incorporation of metal oxides, such as ZnO, TiO2, and Nb2O5 nanomaterials into organic photovoltaics have been commercialized using full roll-to-roll processing.[95] A 13.2% power conversion efficiency is claimed in Si nanowire/PEDOT:PSS hybrid solar cells.[96]

#### Quantum dot with nanowire in solar cells

Another potential use involves capped single-crystal ZnO nanowires with CdSe quantum dots, immersed in mercaptopropionic acid as hole transport medium in order to obtain a QD-sensitized solar cell. The morphology of the nanowires allowed the electrons to have a direct pathway to the photoanode. This form of solar cell exhibits 50–60% internal quantum efficiencies.[97]

Nanowires with quantum dot coatings on silicon nanowires (SiNW) and carbon quantum dots. The use of SiNWs instead of planar silicon enhances the antiflection properties of Si.[98] The SiNW exhibits a light-trapping effect due to light trapping in the SiNW. This use of SiNWs in conjunction with carbon quantum dots resulted in a solar cell that reached 9.10% PCE.[98]

Graphene quantum dots have also been blended with organic electronic materials to improve efficiency and lower cost in photovoltaic devices and organic light emitting diodes (OLEDs) compared to graphene sheets. These graphene quantum dots were functionalized with organic ligands that experience photoluminescence from UV-Vis absorption.[99]

### Light emitting diodes

Several methods are proposed for using quantum dots to improve existing light-emitting diode (LED) design, including quantum dot light-emitting diode (QD-LED or QLED) displays, and quantum dot white-light-emitting diode (QD-WLED) displays. Because quantum dots naturally produce monochromatic light, they can be more efficient than light sources which must be color filtered. QD-LEDs can be fabricated on a silicon substrate, which allows them to be integrated onto standard silicon-based integrated circuits or microelectromechanical systems.[100]

### Quantum dot displays

Main page: Physics:Quantum dot display

Quantum dots are valued for displays because they emit light in very specific gaussian distributions. This can result in a display with visibly more accurate colors.

A conventional color liquid crystal display (LCD) is usually backlit by fluorescent lamps (CCFLs) or conventional white LEDs that are color filtered to produce red, green, and blue pixels. Quantum dot displays use blue-emitting LEDs rather than white LEDs as the light sources. The converting part of the emitted light is converted into pure green and red light by the corresponding color quantum dots placed in front of the blue LED or using a quantum dot infused diffuser sheet in the backlight optical stack. Blank pixels are also used to allow the blue LED light to still generate blue hues. This type of white light as the backlight of an LCD panel allows for the best color gamut at lower cost than an RGB LED combination using three LEDs.[101]

Another method by which quantum dot displays can be achieved is the electroluminescent (EL) or electro-emissive method. This involves embedding quantum dots in each individual pixel. These are then activated and controlled via an electric current application.[102] Since this is often light emitting itself, the achievable colors may be limited in this method.[103] Electro-emissive QD-LED TVs exist in laboratories only.

The ability of QDs to precisely convert and tune a spectrum makes them attractive for LCD displays. Previous LCD displays can waste energy converting red-green poor, blue-yellow rich white light into a more balanced lighting. By using QDs, only the necessary colors for ideal images are contained in the screen. The result is a screen that is brighter, clearer, and more energy-efficient. The first commercial application of quantum dots was the Sony XBR X900A series of flat panel televisions released in 2013.[104]

In June 2006, QD Vision announced technical success in making a proof-of-concept quantum dot display and show a bright emission in the visible and near infrared region of the spectrum. A QD-LED integrated at a scanning microscopy tip was used to demonstrate fluorescence near-field scanning optical microscopy (NSOM) imaging.[105]

### Photodetector devices

Quantum dot photodetectors (QDPs) can be fabricated either via solution-processing,[106] or from conventional single-crystalline semiconductors.[107] Conventional single-crystalline semiconductor QDPs are precluded from integration with flexible organic electronics due to the incompatibility of their growth conditions with the process windows required by organic semiconductors. On the other hand, solution-processed QDPs can be readily integrated with an almost infinite variety of substrates, and also postprocessed atop other integrated circuits. Such colloidal QDPs have potential applications in visible- and infrared-light cameras,[108] machine vision, industrial inspection, spectroscopy, and fluorescent biomedical imaging.

### Photocatalysts

Main page: Physics:Photocatalysis

Quantum dots also function as photocatalysts for the light driven chemical conversion of water into hydrogen as a pathway to solar fuel. In photocatalysis, electron hole pairs formed in the dot under band gap excitation drive redox reactions in the surrounding liquid. Generally, the photocatalytic activity of the dots is related to the particle size and its degree of quantum confinement.[109] This is because the band gap determines the chemical energy that is stored in the dot in the excited state. An obstacle for the use of quantum dots in photocatalysis is the presence of surfactants on the surface of the dots. These surfactants (or ligands) interfere with the chemical reactivity of the dots by slowing down mass transfer and electron transfer processes. Also, quantum dots made of metal chalcogenides are chemically unstable under oxidizing conditions and undergo photo corrosion reactions.

## Theory

Quantum dots are theoretically described as a point-like, or zero dimensional (0D) entity. Most of their properties depend on the dimensions, shape, and materials of which QDs are made. Generally, QDs present different thermodynamic properties from their bulk materials. One of these effects is melting-point depression. Optical properties of spherical metallic QDs are well described by the Mie scattering theory.

## Quantum confinement in semiconductors

3D confined electron wave functions in a quantum dot. Here, rectangular and triangular-shaped quantum dots are shown. Energy states in rectangular dots are more s-type and p-type. However, in a triangular dot the wave functions are mixed due to confinement symmetry. (Click for animation)

Main page: Physics:Potential well

The energy levels of a single particle in a quantum dot can be predicted using the particle in a box model in which the energies of states depend on the length of the box. For an exciton inside a quantum dot, there is also the Coulomb interaction between the negatively charged electron and the positively charged hole. By comparing the quantum dot's size to the exciton Bohr radius, three regimes can be defined. In the 'strong confinement regime', the quantum dot's radius is much smaller than the exciton Bohr radius, respectively the confinement energy dominates over the Coulomb interactions.[110] In the 'weak confinement' regime, the quantum dot is larger than the exciton Bohr radius, respectively the confinement energy is smaller than the Coulomb interactions between electron and hole. The regime where the exciton Bohr radius and confinement potential are comparable is called the 'intermediate confinement regime'.[111]

Splitting of energy levels for small quantum dots due to the quantum confinement effect. The horizontal axis is the radius, or the size, of the quantum dots and ab* is the Exciton Bohr radius.

Band gap energy
The band gap can become smaller in the strong confinement regime as the energy levels split up. The exciton Bohr radius can be expressed as:

[math]\displaystyle{ a^*_{\rm B}=\varepsilon_{\rm r}\left(\frac{m}{\mu}\right) a_{\rm B} }[/math]
where aB=0.053 nm is the Bohr radius, m is the mass, μ is the reduced mass, and εr is the size-dependent dielectric constant (relative permittivity). This results in the increase in the total emission energy (the sum of the energy levels in the smaller band gaps in the strong confinement regime is larger than the energy levels in the band gaps of the original levels in the weak confinement regime) and the emission at various wavelengths. If the size distribution of QDs is not enough peaked, the convolution of multiple emission wavelengths is observed as a continuous spectra.
Confinement energy
The exciton entity can be modeled using the particle in the box. The electron and the hole can be seen as hydrogen in the Bohr model with the hydrogen nucleus replaced by the hole of positive charge and negative electron mass. Then the energy levels of the exciton can be represented as the solution to the particle in a box at the ground level (n = 1) with the mass replaced by the reduced mass. Thus by varying the size of the quantum dot, the confinement energy of the exciton can be controlled.
Bound exciton energy
There is Coulomb attraction between the negatively charged electron and the positively charged hole. The negative energy involved in the attraction is proportional to Rydberg's energy and inversely proportional to square of the size-dependent dielectric constant[112] of the semiconductor. When the size of the semiconductor crystal is smaller than the Exciton Bohr radius, the Coulomb interaction must be modified to fit the situation.

Therefore, the sum of these energies can be represented as:

[math]\displaystyle{ \begin{align} E_\textrm{confinement} &= \frac{\hbar^2\pi^2}{2 a^2}\left(\frac{1}{m_{\rm e}} + \frac{1}{m_h}\right) = \frac{\hbar^2\pi^2}{2\mu a^2}\\\ E_\textrm{exciton} &= -\frac{1}{\epsilon_{\rm r}^2}\frac{\mu}{m_{\rm e}}R_y = -R_y^*\\\ E &= E_\textrm{band gap} + E_\textrm{confinement} + E_\textrm{exciton}\\\ &= E_\textrm{band gap} + \frac{\hbar^2\pi^2}{2\mu a^2} - R^*_y \end{align} }[/math]

where μ is the reduced mass, a is the radius of the quantum dot, me is the free electron mass, mh is the hole mass, and εr is the size-dependent dielectric constant.

Although the above equations were derived using simplifying assumptions, they imply that the electronic transitions of the quantum dots will depend on their size. These quantum confinement effects are apparent only below the critical size. Larger particles do not exhibit this effect. This effect of quantum confinement on the quantum dots has been repeatedly verified experimentally[113] and is a key feature of many emerging electronic structures.[114]

The Coulomb interaction between confined carriers can also be studied by numerical means when results unconstrained by asymptotic approximations are pursued.[115]

Besides confinement in all three dimensions (i.e., a quantum dot), other quantum confined semiconductors include:

* Quantum wires, which confine electrons or holes in two spatial dimensions and allow free propagation in the third.
* Quantum wells, which confine electrons or holes in one dimension and allow free propagation in two dimensions.

### Models

A variety of theoretical frameworks exist to model optical, electronic, and structural properties of quantum dots. These may be broadly divided into quantum mechanical, semiclassical, and classical.

### Quantum mechanics

Quantum mechanical models and simulations of quantum dots often involve the interaction of electrons with a pseudopotential or random matrix.[116]

#### Semiclassical

Semiclassical models of quantum dots frequently incorporate a chemical potential. For example, the thermodynamic chemical potential of an N-particle system is given by

[math]\displaystyle{ \mu(N) = E(N) - E(N-1) }[/math]

whose energy terms may be obtained as solutions of the Schrödinger equation. The definition of capacitance,

[math]\displaystyle{ {1\over C} \equiv {\Delta \,V\over\Delta \,Q} }[/math],

with the potential difference

[math]\displaystyle{ \Delta \,V = {\Delta \,\mu \,\over e} = {\mu(N+\Delta \,N) -\mu(N) \over e} }[/math]

may be applied to a quantum dot with the addition or removal of individual electrons,

[math]\displaystyle{ \Delta \,N = 1 }[/math] and [math]\displaystyle{ \Delta \,Q = e }[/math].

Then

[math]\displaystyle{ C(N) = {e^2\over\mu(N+1)-\mu(N)} = {e^2 \over I(N)-A(N)} }[/math]

is the quantum capacitance of a quantum dot, where we denoted by I(N) the ionization potential and by A(N) the electron affinity of the N-particle system.[117]

#### Classical mechanics

Classical models of electrostatic properties of electrons in quantum dots are similar in nature to the Thomson problem of optimally distributing electrons on a unit sphere.

The classical electrostatic treatment of electrons confined to spherical quantum dots is similar to their treatment in the Thomson,[118] or plum pudding model, of the atom.[119]

The classical treatment of both two-dimensional and three-dimensional quantum dots exhibit electron shell-filling behavior. A "periodic table of classical artificial atoms" has been described for two-dimensional quantum dots.[120] As well, several connections have been reported between the three-dimensional Thomson problem and electron shell-filling patterns found in naturally-occurring atoms found throughout the periodic table.[121] This latter work originated in classical electrostatic modeling of electrons in a spherical quantum dot represented by an ideal dielectric sphere.[122]

## History

The term quantum dot was coined in 1986.[123] They were first synthesized in a glass matrix by Alexey Ekimov in 1981[124][125][126][127] and in colloidal suspension[128] by Louis Brus in 1983.[129][130] They were first theorized by Alexander Efros in 1982.[131]

## See also

* Paul Alivisatos
* Uri Banin
* Moungi Bawendi
* Cadmium-free quantum dot
* Carbon quantum dot
* Core–shell semiconductor nanocrystal
* Langmuir-Blodgett film
* Nanocrystal solar cell
* Shuming Nie
* Quantum dot laser
* Quantum dot single-photon source
* Quantum point contact
* Mark Reed (physicist)
* Superatom
* Trojan wave packet

## References

1. ↑ Silbey, Robert J.; Alberty, Robert A.; Bawendi, Moungi G. (2005). Physical Chemistry, 4th ed. John Wiley & Sons. p. 835.
2. ↑ Ashoori, R. C. (1996). "Electrons in artificial atoms". Nature 379 (6564): 413–419. doi:10.1038/379413a0. Bibcode: 1996Natur.379..413A.
3. ↑ Kastner, M. A. (1993). "Artificial Atoms". Physics Today 46 (1): 24–31. doi:10.1063/1.881393. Bibcode: 1993PhT....46a..24K.
4. ↑ Banin, Uri; Cao, YunWei; Katz, David; Millo, Oded (August 1999). "Identification of atomic-like electronic states in indium arsenide nanocrystal quantum dots" (in en). Nature 400 (6744): 542–544. doi:10.1038/22979. ISSN 1476-4687. Bibcode: 1999Natur.400..542B. https://www.nature.com/articles/22979.
5. ↑ Cui, Jiabin; Panfil, Yossef E.; Koley, Somnath; Shamalia, Doaa; Waiskopf, Nir; Remennik, Sergei; Popov, Inna; Oded, Meirav et al. (2019-12-16). "Colloidal quantum dot molecules manifesting quantum coupling at room temperature" (in en). Nature Communications 10 (1): 5401. doi:10.1038/s41467-019-13349-1. ISSN 2041-1723. PMID 31844043. Bibcode: 2019NatCo..10.5401C.
6. ↑ Cherniukh, Ihor; Rainò, Gabriele; Stöferle, Thilo; Burian, Max; Travesset, Alex; Naumenko, Denys; Amenitsch, Heinz; Erni, Rolf et al. (May 2021). "Perovskite-type superlattices from lead halide perovskite nanocubes" (in en). Nature 593 (7860): 535–542. doi:10.1038/s41586-021-03492-5. ISSN 1476-4687. https://www.nature.com/articles/s41586-021-03492-5.
7. ↑ Septianto, Ricky Dwi; Miranti, Retno; Kikitsu, Tomoka; Hikima, Takaaki; Hashizume, Daisuke; Matsushita, Nobuhiro; Iwasa, Yoshihiro; Bisri, Satria Zulkarnaen (2023-05-26). "Enabling metallic behaviour in two-dimensional superlattice of semiconductor colloidal quantum dots" (in en). Nature Communications 14 (1): 2670. doi:10.1038/s41467-023-38216-y. ISSN 2041-1723. https://www.nature.com/articles/s41467-023-38216-y.
8. ↑ 8.0 8.1 Murray, C. B.; Kagan, C. R.; Bawendi, M. G. (2000). "Synthesis and Characterization of Monodisperse Nanocrystals and Close-Packed Nanocrystal Assemblies". Annual Review of Materials Research 30 (1): 545–610. doi:10.1146/annurev.matsci.30.1.545. Bibcode: 2000AnRMS..30..545M.
9. ↑ Brus, L.E. (2007). "Chemistry and Physics of Semiconductor Nanocrystals". http://www.columbia.edu/cu/chemistry/fac-bios/brus/group/pdf-files/semi_nano_website_2007.pdf.
10. ↑ "Quantum Dots". http://www.nanosysinc.com/what-we-do/quantum-dots/.
11. ↑ Huffaker, D. L.; Park, G.; Zou, Z.; Shchekin, O. B.; Deppe, D. G. (1998). "1.3 μm room-temperature GaAs-based quantum-dot laser". Applied Physics Letters 73 (18): 2564–2566. doi:10.1063/1.122534. ISSN 0003-6951. Bibcode: 1998ApPhL..73.2564H.
12. ↑ Lodahl, Peter; Mahmoodian, Sahand; Stobbe, Søren (2015). "Interfacing single photons and single quantum dots with photonic nanostructures". Reviews of Modern Physics 87 (2): 347–400. doi:10.1103/RevModPhys.87.347. ISSN 0034-6861. Bibcode: 2015RvMP...87..347L.
13. ↑ Eisaman, M. D.; Fan, J.; Migdall, A.; Polyakov, S. V. (2011). "Invited Review Article: Single-photon sources and detectors". Review of Scientific Instruments 82 (7): 071101–071101–25. doi:10.1063/1.3610677. ISSN 0034-6748. PMID 21806165. Bibcode: 2011RScI...82g1101E.
14. ↑ Senellart, Pascale; Solomon, Glenn; White, Andrew (2017). "High-performance semiconductor quantum-dot single-photon sources". Nature Nanotechnology 12 (11): 1026–1039. doi:10.1038/nnano.2017.218. ISSN 1748-3387. PMID 29109549. Bibcode: 2017NatNa..12.1026S.
15. ↑ Loss, Daniel; DiVincenzo, David P. (1998). "Quantum computation with quantum dots". Physical Review A 57 (1): 120–126. doi:10.1103/PhysRevA.57.120. ISSN 1050-2947. Bibcode: 1998PhRvA..57..120L.
16. ↑ 16.0 16.1 Michalet, X.; Pinaud, F. F.; Bentolila, L. A.; Tsay, J. M.; Doose, S.; Li, J. J.; Sundaresan, G.; Wu, A. M. et al. (2005). "Quantum Dots for Live Cells, in Vivo Imaging, and Diagnostics". Science 307 (5709): 538–44. doi:10.1126/science.1104274. PMID 15681376. Bibcode: 2005Sci...307..538M.
17. ↑ Wagner, Christian; Green, Matthew F. B.; Leinen, Philipp; Deilmann, Thorsten; Krüger, Peter; Rohlfing, Michael; Temirov, Ruslan; Tautz, F. Stefan (2015-07-06). "Scanning Quantum Dot Microscopy" (in en). Physical Review Letters 115 (2): 026101. doi:10.1103/PhysRevLett.115.026101. ISSN 0031-9007. PMID 26207484. Bibcode: 2015PhRvL.115b6101W.
18. ↑ Ramírez, H. Y.; Flórez J.; Camacho A. S. (2015). "Efficient control of coulomb enhanced second harmonic generation from excitonic transitions in quantum dot ensembles". Phys. Chem. Chem. Phys. 17 (37): 23938–46. doi:10.1039/C5CP03349G. PMID 26313884. Bibcode: 2015PCCP...1723938R. https://semanticscholar.org/paper/14663bc7079d437c9186719e572923294ce6f798.
19. ↑ Coe-Sullivan, S.; Steckel, J. S.; Woo, W.-K.; Bawendi, M. G.; Bulović, V. (2005-07-01). "Large-Area Ordered Quantum-Dot Monolayers via Phase Separation During Spin-Casting". Advanced Functional Materials 15 (7): 1117–1124. doi:10.1002/adfm.200400468.
20. ↑ Xu, Shicheng; Dadlani, Anup L.; Acharya, Shinjita; Schindler, Peter; Prinz, Fritz B. (2016). "Oscillatory barrier-assisted Langmuir–Blodgett deposition of large-scale quantum dot monolayers". Applied Surface Science 367: 500–506. doi:10.1016/j.apsusc.2016.01.243. Bibcode: 2016ApSS..367..500X.
21. ↑ Gorbachev, I. A.; Goryacheva, I. Yu; Glukhovskoy, E. G. (2016-06-01). "Investigation of Multilayers Structures Based on the Langmuir-Blodgett Films of CdSe/ZnS Quantum Dots" (in en). BioNanoScience 6 (2): 153–156. doi:10.1007/s12668-016-0194-0. ISSN 2191-1630.
22. ↑ Achermann, Marc; Petruska, Melissa A.; Crooker, Scott A.; Klimov, Victor I. (2003-12-01). "Picosecond Energy Transfer in Quantum Dot Langmuir−Blodgett Nanoassemblies". The Journal of Physical Chemistry B 107 (50): 13782–13787. doi:10.1021/jp036497r. ISSN 1520-6106. Bibcode: 2003cond.mat.10127A.
23. ↑ Protesescu, Loredana (2015). "Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X=Cl, Br, and/or I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut Profiling". Nano Letters 15 (6): 3692–3696. doi:10.1021/nl5048779. PMID 25633588.
24. ↑ Mangolini, L.; Thimsen, E.; Kortshagen, U. (2005). "High-yield plasma synthesis of luminescent silicon nanocrystals". Nano Letters 5 (4): 655–659. doi:10.1021/nl050066y. PMID 15826104. Bibcode: 2005NanoL...5..655M.
25. ↑ Knipping, J.; Wiggers, H.; Rellinghaus, B.; Roth, P.; Konjhodzic, D.; Meier, C. (2004). "Synthesis of high purity silicon nanoparticles in a low Pressure microwave reactor". Journal of Nanoscience and Nanotechnology 4 (8): 1039–1044. doi:10.1166/jnn.2004.149. PMID 15656199. https://semanticscholar.org/paper/d9b1e6dd8495b8f382112fdfa323f1cce5c3841f.
26. ↑ Sankaran, R. M.; Holunga, D.; Flagan, R. C.; Giapis, K. P. (2005). "Synthesis of blue luminescent Si nanoparticles using atmospheric-pressure microdischarges". Nano Letters 5 (3): 537–541. doi:10.1021/nl0480060. PMID 15755110. Bibcode: 2005NanoL...5..537S. https://authors.library.caltech.edu/59709/2/nl0480060si20041201_112408.pdf.
27. ↑ Kortshagen, U (2009). "Nonthermal plasma synthesis of semiconductor nanocrystals". J. Phys. D: Appl. Phys. 42 (11): 113001. doi:10.1088/0022-3727/42/11/113001. Bibcode: 2009JPhD...42k3001K.
28. ↑ Pi, X. D.; Kortshagen, U. (2009). "Nonthermal plasma synthesized freestanding silicon–germanium alloy nanocrystals". Nanotechnology 20 (29): 295602. doi:10.1088/0957-4484/20/29/295602. PMID 19567968. Bibcode: 2009Nanot..20C5602P.
29. ↑ Pi, X. D.; Gresback, R.; Liptak, R. W.; Campbell, S. A.; Kortshagen, U. (2008). "Doping efficiency, dopant location, and oxidation of Si nanocrystals". Applied Physics Letters 92 (2): 123102. doi:10.1063/1.2830828. Bibcode: 2008ApPhL..92b3102S. https://pure.rug.nl/ws/files/63542958/1.2830828.pdf.
30. ↑ Ni, Z. Y.; Pi, X. D.; Ali, M.; Zhou, S.; Nozaki, T.; Yang, D. (2015). "Freestanding doped silicon nanocrystals synthesized by plasma". J. Phys. D: Appl. Phys. 48 (31): 314006. doi:10.1088/0022-3727/48/31/314006. Bibcode: 2015JPhD...48E4006N.
31. ↑ Pereira, R. N.; Almeida, A. J. (2015). "Doped semiconductor nanoparticles synthesized in gas-phase plasmas". J. Phys. D: Appl. Phys. 48 (31): 314005. doi:10.1088/0022-3727/48/31/314005. Bibcode: 2015JPhD...48E4005P.
32. ↑ Mangolini, L.; Kortshagen, U. (2007). "Plasma-assisted synthesis of silicon nanocrystal inks". Advanced Materials 19 (18): 2513–2519. doi:10.1002/adma.200700595. Bibcode: 2007AdM....19.2513M.
33. ↑ Pi, X. D.; Yu, T.; Yang, D. (2014). "Water-dispersible silicon-quantum-dot-containing micelles self-assembled from an amphiphilic polymer". Part. Part. Syst. Charact. 31 (7): 751–756. doi:10.1002/ppsc.201300346.
34. ↑ Petta, J. R.; Johnson, A. C.; Taylor, J. M.; Laird, E. A.; Yacoby, A.; Lukin, M. D.; Marcus, C. M.; Hanson, M. P. et al. (30 September 2005). "Coherent Manipulation of Coupled Electron Spins in Semiconductor Quantum Dots". Science 309 (5744): 2180–2184. doi:10.1126/science.1116955. ISSN 0036-8075. PMID 16141370. Bibcode: 2005Sci...309.2180P.
35. ↑ Branny, Artur; Kumar, Santosh; Proux, Raphaël; Gerardot, Brian D (22 May 2017). "Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor". Nature Communications 8 (1): 15053. doi:10.1038/ncomms15053. PMID 28530219. Bibcode: 2017NatCo...815053B.
36. ↑ Clark, Pip; Radtke, Hanna; Pengpad, Atip; Williamson, Andrew; Spencer, Ben; Hardman, Samantha; Neo, Darren; Fairclough, Simon et al. (2017). "The Passivating Effect of Cadmium in PbS / CdS Colloidal Quantum Dot Solar Cells Probed by nm-Scale Depth Profiling". Nanoscale 9 (18): 6056–6067. doi:10.1039/c7nr00672a. PMID 28443889.
37. ↑ Stranski, Ivan N.; Krastanow, Lubomir (1938). "Zur Theorie der orientierten Ausscheidung von Ionenkristallen aufeinander". Abhandlungen der Mathematisch-Naturwissenschaftlichen Klasse IIb. Akademie der Wissenschaften Wien 146: 797–810.
38. ↑ Leonard, D.; Pond, K.; Petroff, P. M. (1994). "Critical layer thickness for self-assembled InAs islands on GaAs". Physical Review B 50 (16): 11687–11692. doi:10.1103/PhysRevB.50.11687. ISSN 0163-1829. PMID 9975303. Bibcode: 1994PhRvB..5011687L.
39. ↑ Yoneda, Jun; Takeda, Kenta; Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R.; Allison, Giles; Honda, Takumu; Kodera, Tetsuo et al. (18 December 2017). "A quantum-dot spin qubit with coherence limited by charge noise and fidelity higher than 99.9%". Nature Nanotechnology 13 (2): 102–106. doi:10.1038/s41565-017-0014-x. ISSN 1748-3387. PMID 29255292.
40. ↑ Turchetti, Marco; Homulle, Harald; Sebastiano, Fabio; Ferrari, Giorgio; Charbon, Edoardo; Prati, Enrico (2015). "Tunable single hole regime of a silicon field effect transistor in standard CMOS technology". Applied Physics Express 9 (11): 014001. doi:10.7567/APEX.9.014001.
41. ↑ "Ordering of quantum dots using genetically engineered viruses". Science 296 (5569): 892–5. 2002. doi:10.1126/science.1068054. PMID 11988570. Bibcode: 2002Sci...296..892L.
42. ↑ "Selection of peptides with semiconductor binding specificity for directed nanocrystal assembly". Nature 405 (6787): 665–8. 2000. doi:10.1038/35015043. PMID 10864319. Bibcode: 2000Natur.405..665W.
43. ↑ Jawaid A.M.; Chattopadhyay S.; Wink D.J.; Page L.E.; Snee P.T. (2013). "A". ACS Nano 7 (4): 3190–3197. doi:10.1021/nn305697q. PMID 23441602.
44. ↑ Continuous Flow Synthesis Method for Fluorescent Quantum Dots. Azonano.com (1 June 2013). Retrieved on 2015-07-19.
45. ↑ Quantum Materials Corporation and the Access2Flow Consortium (2011). "Quantum materials corp achieves milestone in High Volume Production of Quantum Dots". http://www.flowid.nl/news/index.html#20110627.
46. ↑ "Nanoco and Dow tune in for sharpest picture yet". The Times. 25 September 2014. http://www.thetimes.co.uk/tto/business/industries/technology/article4217122.ece.
47. ↑ MFTTech (24 March 2015). "LG Electronics Partners with Dow to Commercialize LGs New Ultra HD TV with Quantum Dot Technology". http://www.mfrtech.com/news/lg_electronics_partners_with_dow_to_commercialize_lgs_new_ultra_hd_tv_with_quantum_dot_technology.
48. ↑ Hauser, Charlotte A. E.; Zhang, Shuguang (2010). "Peptides as biological semiconductors". Nature 468 (7323): 516–517. doi:10.1038/468516a. PMID 21107418. Bibcode: 2010Natur.468..516H.
49. ↑ 49.0 49.1 Hardman, R. (2006). "A Toxicologic Review of Quantum Dots: Toxicity Depends on Physicochemical and Environmental Factors". Environmental Health Perspectives 114 (2): 165–72. doi:10.1289/ehp.8284. PMID 16451849.
50. ↑ 50.0 50.1 Pelley, J. L.; Daar, A. S.; Saner, M. A. (2009). "State of Academic Knowledge on Toxicity and Biological Fate of Quantum Dots". Toxicological Sciences 112 (2): 276–296. doi:10.1093/toxsci/kfp188. PMID 19684286.
51. ↑ 51.0 51.1 51.2 51.3 Tsoi, Kim M.; Dai, Qin; Alman, Benjamin A.; Chan, Warren C. W. (2013-03-19). "Are Quantum Dots Toxic? Exploring the Discrepancy Between Cell Culture and Animal Studies". Accounts of Chemical Research 46 (3): 662–671. doi:10.1021/ar300040z. PMID 22853558.
52. ↑ Derfus, Austin M.; Chan, Warren C. W.; Bhatia, Sangeeta N. (2004-01-01). "Probing the Cytotoxicity of Semiconductor Quantum Dots". Nano Letters 4 (1): 11–18. doi:10.1021/nl0347334. PMID 28890669. Bibcode: 2004NanoL...4...11D.
53. ↑ Liu, Wei; Zhang, Shuping; Wang, Lixin; Qu, Chen; Zhang, Changwen; Hong, Lei; Yuan, Lin; Huang, Zehao et al. (2011-09-29). "CdSe Quantum Dot (QD)-Induced Morphological and Functional Impairments to Liver in Mice". PLOS ONE 6 (9): e24406. doi:10.1371/journal.pone.0024406. PMID 21980346. Bibcode: 2011PLoSO...624406L.
54. ↑ Parak, W.j.; Boudreau, R.; Le Gros, M.; Gerion, D.; Zanchet, D.; Micheel, C.m.; Williams, S.c.; Alivisatos, A.p. et al. (2002-06-18). "Cell Motility and Metastatic Potential Studies Based on Quantum Dot Imaging of Phagokinetic Tracks". Advanced Materials 14 (12): 882–885. doi:10.1002/1521-4095(20020618)14:12<882::AID-ADMA882>3.0.CO;2-Y. https://digital.library.unt.edu/ark:/67531/metadc780765/.
55. ↑ Green, Mark; Howman, Emily (2005). "Semiconductor quantum dots and free radical induced DNA nicking". Chemical Communications (1): 121–3. doi:10.1039/b413175d. PMID 15614393.
56. ↑ Hauck, T. S.; Anderson, R. E.; Fischer, H. C.; Newbigging, S.; Chan, W. C. W. (2010). "In vivo Quantum-Dot Toxicity Assessment". Small 6 (1): 138–44. doi:10.1002/smll.200900626. PMID 19743433.
57. ↑ Soo Choi, Hak; Liu, Wenhao; Misra, Preeti; Tanaka, Eiichi; Zimmer, John P.; Itty Ipe, Binil; Bawendi, Moungi G.; Frangioni, John V. (2007-10-01). "Renal clearance of quantum dots". Nature Biotechnology 25 (10): 1165–1170. doi:10.1038/nbt1340. PMID 17891134.
58. ↑ Fischer, Hans C.; Hauck, Tanya S.; Gómez-Aristizábal, Alejandro; Chan, Warren C. W. (2010-06-18). "Exploring Primary Liver Macrophages for Studying Quantum Dot Interactions with Biological Systems". Advanced Materials 22 (23): 2520–2524. doi:10.1002/adma.200904231. PMID 20491094. Bibcode: 2010AdM....22.2520F.
59. ↑ Van Driel; A. F. (2005). "Frequency-Dependent Spontaneous Emission Rate from CdSe and CdTe Nanocrystals: Influence of Dark States". Physical Review Letters 95 (23): 236804. doi:10.1103/PhysRevLett.95.236804. PMID 16384329. Bibcode: 2005PhRvL..95w6804V. http://cops.tnw.utwente.nl/pdf/05/PHYSICAL REVIEW LETTERS 95 236804 (2005).pdf. Retrieved 16 September 2007.
60. ↑ Leatherdale, C. A.; Woo, W. -K.; Mikulec, F. V.; Bawendi, M. G. (2002). "On the Absorption Cross Section of CdSe Nanocrystal Quantum Dots". The Journal of Physical Chemistry B 106 (31): 7619–7622. doi:10.1021/jp025698c.
61. ↑ Torres-Torres, C; López-Suárez, A; Can-Uc, B; Rangel-Rojo, R; Tamayo-Rivera, L; Oliver, A (2015-07-24). "Collective optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and gold nanoparticles embedded in ion-implanted silica". Nanotechnology 26 (29): 295701. doi:10.1088/0957-4484/26/29/295701. ISSN 0957-4484. PMID 26135968. Bibcode: 2015Nanot..26C5701T. https://iopscience.iop.org/article/10.1088/0957-4484/26/29/295701.
62. ↑ D. Loss and D. P. DiVincenzo, "Quantum computation with quantum dots", Phys. Rev. A 57, p120 (1998); on arXiv.org in January 1997
63. ↑ Yazdani, Sajad; Pettes, Michael Thompson (2018-10-26). "Nanoscale self-assembly of thermoelectric materials: a review of chemistry-based approaches". Nanotechnology 29 (43): 432001. doi:10.1088/1361-6528/aad673. ISSN 0957-4484. PMID 30052199. Bibcode: 2018Nanot..29Q2001Y. http://stacks.iop.org/0957-4484/29/i=43/a=432001?key=crossref.43d640c436a1da68b96dfc52566c2a26.
64. ↑ Bux, Sabah K.; Fleurial, Jean-Pierre; Kaner, Richard B. (2010). "Nanostructured materials for thermoelectric applications" (in en). Chemical Communications 46 (44): 8311–24. doi:10.1039/c0cc02627a. ISSN 1359-7345. PMID 20922257.
65. ↑ Zhao, Yixin; Dyck, Jeffrey S.; Burda, Clemens (2011). "Toward high-performance nanostructured thermoelectric materials: the progress of bottom-up solution chemistry approaches" (in en). Journal of Materials Chemistry 21 (43): 17049. doi:10.1039/c1jm11727k. ISSN 0959-9428. https://collected.jcu.edu/cgi/viewcontent.cgi?article=1004&context=phys-facpub.
66. ↑ Achermann, M.; Petruska, M. A.; Smith, D. L.; Koleske, D. D.; Klimov, V. I. (2004). "Energy-transfer pumping of semiconductor nanocrystals using an epitaxial quantum well". Nature 429 (6992): 642–646. doi:10.1038/nature02571. PMID 15190347. Bibcode: 2004Natur.429..642A.
67. ↑ Chern, Margaret; Kays, Joshua C; Bhuckory, Shashi; Dennis, Allison M (2019-01-24). "Sensing with photoluminescent semiconductor quantum dots". Methods and Applications in Fluorescence 7 (1): 012005. doi:10.1088/2050-6120/aaf6f8. ISSN 2050-6120. PMID 30530939. PMC 7233465. Bibcode: 2019MApFl...7a2005C. https://doi.org/10.1088/2050-6120/aaf6f8.
68. ↑ Mongin C.; Garakyaraghi S.; Razgoniaeva N.; Zamkov M.; Castellano F.N. (2016). "Direct observation of triplet energy transfer from semiconductor nanocrystals". Science 351 (6271): 369–372. doi:10.1126/science.aad6378. PMID 26798011. Bibcode: 2016Sci...351..369M.
69. ↑ 69.0 69.1 Trafton, Anne (18 December 2019). "Storing medical information below the skin's surface". MIT News. https://news.mit.edu/2019/storing-vaccine-history-skin-1218.
70. ↑ 70.0 70.1 Jaklenec, Ana; McHugh, Kevin J.; Langer, Robert S.. "Microneedle tattoo patches and use thereof". US Patent and Trademark Office. https://patents.google.com/patent/US20190015650A1/en.
71. ↑ 71.0 71.1 Walling, M. A.; Novak, Shepard (February 2009). "Quantum Dots for Live Cell and In Vivo Imaging". Int. J. Mol. Sci. 10 (2): 441–491. doi:10.3390/ijms10020441. PMID 19333416.
72. ↑ Juan Carlos Stockert, Alfonso Blázquez-Castro (2017). "Chapter 18 Luminescent Solid-State Markers". Fluorescence Microscopy in Life Sciences. Bentham Science Publishers. pp. 606–641. ISBN 978-1-68108-519-7. https://ebooks.benthamscience.com/book/9781681085180/. Retrieved 24 December 2017.
73. ↑ Marchuk, K.; Guo, Y.; Sun, W.; Vela, J.; Fang, N. (2012). "High-Precision Tracking with Non-blinking Quantum Dots Resolves Nanoscale Vertical Displacement". Journal of the American Chemical Society 134 (14): 6108–11. doi:10.1021/ja301332t. PMID 22458433. http://lib.dr.iastate.edu/chem_pubs/134.
74. ↑ Lane, L. A.; Smith, A. M.; Lian, T.; Nie, S. (2014). "Compact and Blinking-Suppressed Quantum Dots for Single-Particle Tracking in Live Cells". The Journal of Physical Chemistry B 118 (49): 14140–7. doi:10.1021/jp5064325. PMID 25157589.
75. ↑ Spie (2014). "Paul Selvin Hot Topics presentation: New Small Quantum Dots for Neuroscience". SPIE Newsroom. doi:10.1117/2.3201403.17.
76. ↑ Tokumasu, F; Fairhurst, Rm; Ostera, Gr; Brittain, Nj; Hwang, J; Wellems, Te; Dvorak, Ja (2005). "Band 3 modifications in Plasmodium falciparum-infected AA and CC erythrocytes assayed by autocorrelation analysis using quantum dots". Journal of Cell Science 118 (Pt 5): 1091–8. doi:10.1242/jcs.01662. PMID 15731014.
77. ↑ Dahan, M. (2003). "Diffusion Dynamics of Glycine Receptors Revealed by Single-Quantum Dot Tracking". Science 302 (5644): 442–5. doi:10.1126/science.1088525. PMID 14564008. Bibcode: 2003Sci...302..442D.
78. ↑ Howarth, M.; Liu, W.; Puthenveetil, S.; Zheng, Y.; Marshall, L. F.; Schmidt, M. M.; Wittrup, K. D.; Bawendi, M. G. et al. (2008). "Monovalent, reduced-size quantum dots for imaging receptors on living cells". Nature Methods 5 (5): 397–9. doi:10.1038/nmeth.1206. PMID 18425138.
79. ↑ Akerman, M. E.; Chan, W. C. W.; Laakkonen, P.; Bhatia, S. N.; Ruoslahti, E. (2002). "Nanocrystal targeting in vivo". Proceedings of the National Academy of Sciences 99 (20): 12617–21. doi:10.1073/pnas.152463399. PMID 12235356. Bibcode: 2002PNAS...9912617A.
80. ↑ Farlow, J.; Seo, D.; Broaders, K. E.; Taylor, M. J.; Gartner, Z. J.; Jun, Y. W. (2013). "Formation of targeted monovalent quantum dots by steric exclusion". Nature Methods 10 (12): 1203–5. doi:10.1038/nmeth.2682. PMID 24122039.
81. ↑ Dwarakanath, S.; Bruno, J. G.; Shastry, A.; Phillips, T.; John, A.; Kumar, A.; Stephenson, L. D. (2004). "Quantum dot-antibody and aptamer conjugates shift fluorescence upon binding bacteria". Biochemical and Biophysical Research Communications 325 (3): 739–43. doi:10.1016/j.bbrc.2004.10.099. PMID 15541352.
82. ↑ Zherebetskyy D.; Scheele M.; Zhang Y.; Bronstein N.; Thompson C.; Britt D.; Salmeron M.; Alivisatos P. et al. (2014). "Hydroxylation of the surface of PbS nanocrystals passivated with oleic acid". Science 344 (6190): 1380–1384. doi:10.1126/science.1252727. PMID 24876347. Bibcode: 2014Sci...344.1380Z. http://www.escholarship.org/uc/item/6p2408jt.
83. ↑ 83.0 83.1 Ballou, B.; Lagerholm, B. C.; Ernst, L. A.; Bruchez, M. P.; Waggoner, A. S. (2004). "Noninvasive Imaging of Quantum Dots in Mice". Bioconjugate Chemistry 15 (1): 79–86. doi:10.1021/bc034153y. PMID 14733586.
84. ↑ Lu, Zhisong; Li, Chang Ming; Bao, Haifeng; Qiao, Yan; Toh, Yinghui; Yang, Xu (2008-05-20). "Mechanism of antimicrobial activity of CdTe quantum dots". Langmuir: The ACS Journal of Surfaces and Colloids 24 (10): 5445–5452. doi:10.1021/la704075r. ISSN 0743-7463. PMID 18419147.
85. ↑ Abdolmohammadi, Mohammad Hossein; Fallahian, Faranak; Fakhroueian, Zahra; Kamalian, Mozhgan; Keyhanvar, Peyman; M Harsini, Faraz; Shafiekhani, Azizollah (December 2017). "Application of new ZnO nanoformulation and Ag/Fe/ZnO nanocomposites as water-based nanofluids to consider in vitro cytotoxic effects against MCF-7 breast cancer cells". Artificial Cells, Nanomedicine, and Biotechnology 45 (8): 1769–1777. doi:10.1080/21691401.2017.1290643. ISSN 2169-141X. PMID 28278581.
86. ↑ Resch-Genger, Ute; Grabolle, Markus; Cavaliere-Jaricot, Sara; Nitschke, Roland; Nann, Thomas (28 August 2008). "Quantum dots versus organic dyes as fluorescent labels". Nature Methods 5 (9): 763–775. doi:10.1038/nmeth.1248. PMID 18756197.
87. ↑ Algar, W. Russ; Krull, Ulrich J. (7 November 2007). "Quantum dots as donors in fluorescence resonance energy transfer for the bioanalysis of nucleic acids, proteins, and other biological molecules". Analytical and Bioanalytical Chemistry 391 (5): 1609–1618. doi:10.1007/s00216-007-1703-3. PMID 17987281.
88. ↑ Beane, Gary; Boldt, Klaus; Kirkwood, Nicholas; Mulvaney, Paul (7 August 2014). "Energy Transfer between Quantum Dots and Conjugated Dye Molecules". The Journal of Physical Chemistry C 118 (31): 18079–18086. doi:10.1021/jp502033d.
89. ↑ Soo Choi, H.; Liu, W.; Misra, P.; Tanaka, E.; Zimmer, J. P.; Itty Ipe, B.; Bawendi, M. G.; Frangioni, J. V. (2007). "Renal clearance of quantum dots". Nature Biotechnology 25 (10): 1165–70. doi:10.1038/nbt1340. PMID 17891134.
90. ↑ Sharei, A.; Zoldan, J.; Adamo, A.; Sim, W. Y.; Cho, N.; Jackson, E.; Mao, S.; Schneider, S. et al. (2013). "A vector-free microfluidic platform for intracellular delivery". Proceedings of the National Academy of Sciences 110 (6): 2082–7. doi:10.1073/pnas.1218705110. PMID 23341631. Bibcode: 2013PNAS..110.2082S.
91. ↑ Schaller, R.; Klimov, V. (2004). "High Efficiency Carrier Multiplication in PbSe Nanocrystals: Implications for Solar Energy Conversion". Physical Review Letters 92 (18): 186601. doi:10.1103/PhysRevLett.92.186601. PMID 15169518. Bibcode: 2004PhRvL..92r6601S.
92. ↑ Ramiro, Iñigo; Martí, Antonio (July 2021). "Intermediate band solar cells: Present and future" (in en). Progress in Photovoltaics: Research and Applications 29 (7): 705–713. doi:10.1002/pip.3351. ISSN 1062-7995. https://onlinelibrary.wiley.com/doi/10.1002/pip.3351.
93. ↑ Alexandre, M.; Águas, H.; Fortunato, E.; Martins, R.; Mendes, M. J. (2021-11-17). "Light management with quantum nanostructured dots-in-host semiconductors" (in en). Light: Science & Applications 10 (1): 231. doi:10.1038/s41377-021-00671-x. ISSN 2047-7538. PMID 34785654. Bibcode: 2021LSA....10..231A.
94. ↑ 94.0 94.1 Kim, Gi-Hwan; Arquer, F. Pelayo García de; Yoon, Yung Jin; Lan, Xinzheng; Liu, Mengxia; Voznyy, Oleksandr; Yang, Zhenyu; Fan, Fengjia et al. (2015-11-02). "High-Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self-Assembled Monolayers". Nano Letters 15 (11): 7691–7696. doi:10.1021/acs.nanolett.5b03677. PMID 26509283. Bibcode: 2015NanoL..15.7691K.
95. ↑ 95.0 95.1 Krebs, Frederik C.; Tromholt, Thomas; Jørgensen, Mikkel (2010). "Upscaling of polymer solar cell fabrication using full roll-to-roll processing". Nanoscale 2 (6): 873–86. doi:10.1039/b9nr00430k. PMID 20648282. Bibcode: 2010Nanos...2..873K.
96. ↑ Park, Kwang-Tae; Kim, Han-Jung; Park, Min-Joon; Jeong, Jun-Ho; Lee, Jihye; Choi, Dae-Geun; Lee, Jung-Ho; Choi, Jun-Hyuk (2015-07-15). "13.2% efficiency Si nanowire/PEDOT:PSS hybrid solar cell using a transfer-imprinted Au mesh electrode". Scientific Reports 5: 12093. doi:10.1038/srep12093. PMID 26174964. Bibcode: 2015NatSR...512093P.
97. ↑ Leschkies, Kurtis S.; Divakar, Ramachandran; Basu, Joysurya; Enache-Pommer, Emil; Boercker, Janice E.; Carter, C. Barry; Kortshagen, Uwe R.; Norris, David J. et al. (2007-06-01). "Photosensitization of ZnO Nanowires with CdSe Quantum Dots for Photovoltaic Devices". Nano Letters 7 (6): 1793–1798. doi:10.1021/nl070430o. PMID 17503867. Bibcode: 2007NanoL...7.1793L.
98. ↑ 98.0 98.1 Xie, Chao; Nie, Biao; Zeng, Longhui; Liang, Feng-Xia; Wang, Ming-Zheng; Luo, Linbao; Feng, Mei; Yu, Yongqiang et al. (2014-04-22). "Core–Shell Heterojunction of Silicon Nanowire Arrays and Carbon Quantum Dots for Photovoltaic Devices and Self-Driven Photodetectors". ACS Nano 8 (4): 4015–4022. doi:10.1021/nn501001j. PMID 24665986.
99. ↑ Gupta, Vinay; Chaudhary, Neeraj; Srivastava, Ritu; Sharma, Gauri Datt; Bhardwaj, Ramil; Chand, Suresh (2011-07-06). "Luminscent Graphene Quantum Dots for Organic Photovoltaic Devices". Journal of the American Chemical Society 133 (26): 9960–9963. doi:10.1021/ja2036749. PMID 21650464.
100. ↑ "Nano LEDs printed on silicon". 3 July 2009. http://nanotechweb.org/cws/article/lab/39721.
101. ↑ "Quantum Dots: Solution for a Wider Color Gamut". https://pid.samsungdisplay.com/en/learning-center/white-papers/quantum-dot-technology.
102. ↑ "A Guide to the Evolution of Quantum Dot Displays". https://pid.samsungdisplay.com/en/learning-center/white-papers/evolution-of-quantum-dot-technologies.
103. ↑ "Quantum dot white and colored light emitting diodes". https://patents.google.com/patent/US6501091B1/en.
104. ↑ Bullis, Kevin. (11 January 2013) Quantum Dots Produce More Colorful Sony TVs |MIT Technology Review. Technologyreview.com. Retrieved on 2015-07-19.
105. ↑ Hoshino, Kazunori; Gopal, Ashwini; Glaz, Micah S.; Vanden Bout, David A.; Zhang, Xiaojing (2012). "Nanoscale fluorescence imaging with quantum dot near-field electroluminescence". Applied Physics Letters 101 (4): 043118. doi:10.1063/1.4739235. Bibcode: 2012ApPhL.101d3118H. https://semanticscholar.org/paper/eef4dd85db975512b2acfeb965323cbeac7e769c.
106. ↑ Konstantatos, G.; Sargent, E. H. (2009). "Solution-Processed Quantum Dot Photodetectors". Proceedings of the IEEE 97 (10): 1666–1683. doi:10.1109/JPROC.2009.2025612.
107. ↑ Vaillancourt, J.; Lu, X.-J.; Lu, Xuejun (2011). "A High Operating Temperature (HOT) Middle Wave Infrared (MWIR) Quantum-Dot Photodetector". Optics and Photonics Letters 4 (2): 1–5. doi:10.1142/S1793528811000196.
108. ↑ Palomaki P.; and Keuleyan S. (2020): Move over CMOS, here come snapshots by quantum dots. IEEE Spectrum, 25 February 2020. Retrieved 20 March 2020
109. ↑ Zhao, Jing; Holmes, Michael A.; Osterloh, Frank E. (2013). "Quantum Confinement Controls Photocatalysis: A Free Energy Analysis for Photocatalytic Proton Reduction at Cd Se Nanocrystals". ACS Nano 7 (5): 4316–25. doi:10.1021/nn400826h. PMID 23590186.
110. ↑ Jungnickel, V.; Henneberger, F. (October 1996). "Luminescence related processes in semiconductor nanocrystals —The strong confinement regime". Journal of Luminescence 70 (1–6): 238–252. doi:10.1016/0022-2313(96)00058-0. ISSN 0022-2313. Bibcode: 1996JLum...70..238J.
111. ↑ Richter, Marten (26 June 2017). "Nanoplatelets as material system between strong confinement and weak confinement". Physical Review Materials 1 (1): 016001. doi:10.1103/PhysRevMaterials.1.016001. Bibcode: 2017PhRvM...1a6001R.
112. ↑ Brandrup, J.; Immergut, E.H. (1966). Polymer Handbook (2 ed.). New York: Wiley. pp. 240–246.
113. ↑ Khare, Ankur; Wills, Andrew W.; Ammerman, Lauren M.; Noris, David J.; Aydil, Eray S. (2011). "Size control and quantum confinement in Cu2ZnSnX4 nanocrystals". Chem. Commun. 47 (42): 11721–3. doi:10.1039/C1CC14687D. PMID 21952415.
114. ↑ Greenemeier, L. (5 February 2008). "New Electronics Promise Wireless at Warp Speed". Scientific American. http://www.sciam.com/article.cfm?id=metal-insulator-electronics-wireless.
115. ↑ Ramírez, H. Y.; Santana, A. (2012). "Two interacting electrons confined in a 3D parabolic cylindrically symmetric potential, in presence of axial magnetic field: A finite element approach". Comput. Phys. Commun. 183 (8): 1654. doi:10.1016/j.cpc.2012.03.002. Bibcode: 2012CoPhC.183.1654R.
116. ↑ "Spin-orbit coupling, antilocalization, and parallel magnetic fields in quantum dots". Phys. Rev. Lett. 89 (27): 276803. 2002. doi:10.1103/PhysRevLett.89.276803. PMID 12513231. Bibcode: 2002PhRvL..89A6803Z.
117. ↑ Iafrate, G. J.; Hess, K.; Krieger, J. B.; Macucci, M. (1995). "Capacitive nature of atomic-sized structures". Phys. Rev. B 52 (15): 10737–10739. doi:10.1103/physrevb.52.10737. PMID 9980157. Bibcode: 1995PhRvB..5210737I.
118. ↑ Thomson, J.J. (1904). "On the Structure of the Atom: an Investigation of the Stability and Periods of Oscillation of a number of Corpuscles arranged at equal intervals around the Circumference of a Circle; with Application of the Results to the Theory of Atomic Structure" (extract of paper). Philosophical Magazine. Series 6 7 (39): 237–265. doi:10.1080/14786440409463107. http://www.chemteam.info/Chem-History/Thomson-Structure-Atom.html.
119. ↑ Bednarek, S.; Szafran, B.; Adamowski, J. (1999). "Many-electron artificial atoms". Phys. Rev. B 59 (20): 13036–13042. doi:10.1103/PhysRevB.59.13036. Bibcode: 1999PhRvB..5913036B.
120. ↑ Bedanov, V. M.; Peeters, F. M. (1994). "Ordering and phase transitions of charged particles in a classical finite two-dimensional system". Physical Review B 49 (4): 2667–2676. doi:10.1103/PhysRevB.49.2667. PMID 10011100. Bibcode: 1994PhRvB..49.2667B.
121. ↑ LaFave, T. Jr. (2013). "Correspondences between the classical electrostatic Thomson Problem and atomic electronic structure". Journal of Electrostatics 71 (6): 1029–1035. doi:10.1016/j.elstat.2013.10.001.
122. ↑ LaFave, T. Jr. (2013). "The discrete charge dielectric model of electrostatic energy". Journal of Electrostatics 69 (5): 414–418. doi:10.1016/j.elstat.2013.10.001.
123. ↑ Reed, M. A.; Bate, R. T.; Bradshaw, K.; Duncan, W. M.; Frensley, W. R.; Lee, J. W.; Shih, H. D. (1986-01-01). "Spatial quantization in GaAs–AlGaAs multiple quantum dots". Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena 4 (1): 358–360. doi:10.1116/1.583331. ISSN 0734-211X. Bibcode: 1986JVSTB...4..358R.
124. ↑ Екимов АИ; Онущенко АА (1981). "Квантовый размерный эффект в трехмерных микрокристаллах полупроводников". Письма в ЖЭТФ 34: 363–366. http://www.jetpletters.ac.ru/ps/1030/article_15644.pdf.
125. ↑ "Quantum size effect in the optical-spectra of semiconductor micro-crystals". Soviet Physics Semiconductors-USSR 16 (7): 775–778. 1982.
126. ↑ "Quantum size effect in semiconductor microcrystals". Solid State Communications 56 (11): 921–924. 1985. doi:10.1016/S0038-1098(85)80025-9. Bibcode: 1985SSCom..56..921E.
127. ↑ "Nanotechnology Timeline". http://www.nano.gov/timeline.
128. ↑ Kolobkova, E. V.; Nikonorov, N. V.; Aseev, V. A. (2012). "Optical Technologies Silver Nanoclusters Influence on Formation of Quantum Dots in Fluorine Phosphate Glasses". Scientific and Technical Journal of Information Technologies, Mechanics and Optics 5 (12). http://ntv.ifmo.ru/en/article/2412/vliyanie_serebra_na_rost_kvantovyh_tochek_vo_ftorofosfatnyh_steklah.htm.
129. ↑ Rossetti, R.; Nakahara, S.; Brus, L. E. (1983-07-15). "Quantum size effects in the redox potentials, resonance Raman spectra, and electronic spectra of CdS crystallites in aqueous solution". The Journal of Chemical Physics 79 (2): 1086–1088. doi:10.1063/1.445834. ISSN 0021-9606. Bibcode: 1983JChPh..79.1086R.
130. ↑ Brus, L. E. (1984-05-01). "Electron–electron and electron‐hole interactions in small semiconductor crystallites: The size dependence of the lowest excited electronic state". The Journal of Chemical Physics 80 (9): 4403–4409. doi:10.1063/1.447218. ISSN 0021-9606. Bibcode: 1984JChPh..80.4403B. https://semanticscholar.org/paper/529dfcd98ce24b70e7539582eb1b1c96c6457f44.
131. ↑ superadmin. "History of Quantum Dots" (in en-GB). https://nexdot.fr/en/history-of-quantum-dots/.

## Further reading

* Delerue, C.; Lannoo, M. (2004). Nanostructures: Theory and Modelling. Springer. p. 47. ISBN 978-3-540-20694-1. https://archive.org/details/springer_10.1007-978-3-662-08903-3. </ref> Methods to produce quantum-confined semiconductor structures (quantum wires, wells, and dots via grown by advanced epitaxial techniques), nanocrystals by gas-phase, liquid-phase, and solid-phase approaches.
* Norris, D. J. (1995). "Measurement and Assignment of the Size-Dependent Optical Spectrum in Cadmium Selenide (CdSe) Quantum Dots, PhD thesis, MIT". Photoluminescence of a QD vs. particle diameter.

## External links

* Quantum Dots: Technical Status and Market Prospects
* Quantum dots that produce white light could be the light bulb's successor
* Single quantum dots optical properties
* Quantum dot on arxiv.org
* Quantum Dots Research and Technical Data
* Simulation and interactive visualization of Quantum Dots wave function

* v
* t
* e

Emerging technologies

Fields|

| Agriculture|

* Agricultural robot
* Cellular agriculture
* Closed ecological systems
* Cultured meat
* Genetically modified food
* Precision agriculture
* Vertical farming

|

Architecture|

* Arcology
* Building printing
* Contour crafting
* Domed city

Biomedical|

* Artificial uterus
* Ampakine
* Brain transplant
* Cryonics
* Cryoprotectant
* Cryopreservation
* Vitrification
* Suspended animation
* De-extinction
* Genetic engineering
* Gene therapy
* Head transplant
* Isolated brain
* Life extension
* Strategies for Engineered Negligible Senescence
* Nanomedicine
* Nanosensors
* Organ printing
* Personalized medicine
* Regenerative medicine
* Stem-cell therapy
* Tissue engineering
* Robot-assisted surgery
* Synthetic biology
* Synthetic genomics
* Virotherapy
* Oncolytic virus
* Tricorder
* Whole genome sequencing

Displays|

| Next generation|

* FED
* FLCD
* iMoD
* Laser
* LPD
* OLED
* OLET
* QD-LED
* SED
* TPD
* TDEL
* TMOS
* MicroLED

|

Screenless|

* Bionic contact lens
* Head-mounted display
* Head-up display
* Optical head-mounted display
* Virtual retinal display

Other|

* Autostereoscopy
* Flexible display
* Holographic display
* Computer-generated holography
* Multi-primary color display
* Ultra HD
* Volumetric display

Electronics|

* Electronic nose
* E-textiles
* Flexible electronics
* Molecular electronics
* Nanoelectromechanical systems
* Memristor
* Spintronics
* Thermal copper pillar bump
* Twistronics

Energy|

| Production|

* Airborne wind turbine
* Artificial photosynthesis
* Biofuels
* Carbon-neutral fuel
* Concentrated solar power
* Fusion power
* Home fuel cell
* Hydrogen economy
* Methanol economy
* Molten salt reactor
* Nantenna
* Photovoltaic pavement
* Space-based solar power
* Vortex engine

|

Storage|

* Beltway battery
* Compressed air energy storage
* Flywheel energy storage
* Grid energy storage
* Lithium–air battery
* Molten-salt battery
* Nanowire battery
* Research in lithium-ion batteries
* Silicon–air battery
* Thermal energy storage
* Ultracapacitor

Other|

* Smart grid
* Wireless power

Information and
communications

* Ambient intelligence
* Internet of things
* Artificial intelligence
* Applications of artificial intelligence
* Progress in artificial intelligence
* Machine translation
* Mobile translation
* Machine vision
* Semantic Web
* Speech recognition
* Atomtronics
* Carbon nanotube field-effect transistor
* Cybermethodology
* Fourth-generation optical discs
* 3D optical data storage
* Holographic data storage
* GPGPU
* Memory
* CBRAM
* FRAM
* Millipede
* MRAM
* NRAM
* PRAM
* Racetrack memory
* RRAM
* SONOS
* Optical computing
* RFID
* Chipless RFID
* Software-defined radio
* Three-dimensional integrated circuit

Manufacturing|

* 3D printing
* Claytronics
* Molecular assembler
* Utility fog

Materials science|

* Aerogel
* Amorphous metal
* Artificial muscle
* Conductive polymer
* Femtotechnology
* Fullerene
* Graphene
* High-temperature superconductivity
* High-temperature superfluidity
* Linear acetylenic carbon
* Metamaterials
* Metamaterial cloaking
* Metal foam
* Multi-function structures
* Nanotechnology
* Carbon nanotubes
* Molecular nanotechnology
* Nanomaterials
* Picotechnology
* Programmable matter
* Quantum dots
* Silicene
* Superalloy
* Synthetic diamond

Military|

* Antimatter weapon
* Caseless ammunition
* Directed-energy weapon
* Laser
* Maser
* Particle-beam weapon
* Sonic weapon
* Coilgun
* Railgun
* Plasma weapon
* Pure fusion weapon
* Stealth technology
* Vortex ring gun

Neuroscience|

* Artificial brain
* Brain–computer interface
* Electroencephalography
* Mind uploading
* Brain-reading
* Neuroinformatics
* Neuroprosthetics
* Bionic eye
* Brain implant
* Exocortex
* Retinal implant

Quantum|

* Quantum algorithms
* Quantum amplifier
* Quantum bus
* Quantum channel
* Quantum circuit
* Quantum complexity theory
* Quantum computing
* Quantum cryptography
* Quantum dynamics
* Quantum electronics
* Quantum error correction
* Quantum imaging
* Quantum information
* Quantum key distribution
* Quantum logic
* Quantum logic gates
* Quantum machine
* Quantum machine learning
* Quantum metamaterial
* Quantum metrology
* Quantum network
* Quantum neural network
* Quantum optics
* Quantum programming
* Quantum sensing
* Quantum simulator
* Quantum teleportation

Robotics|

* Domotics
* Nanorobotics
* Powered exoskeleton
* Self-reconfiguring modular robot
* Swarm robotics
* Uncrewed vehicle

Space science|

| Launch|

* Fusion rocket
* Non-rocket spacelaunch
* Mass driver
* Orbital ring
* Skyhook
* Space elevator
* Space fountain
* Space tether
* Reusable launch system

|

Propulsion|

* Beam-powered propulsion
* Ion thruster
* Laser propulsion
* Plasma propulsion engine
* Helicon thruster
* VASIMR
* Nuclear pulse propulsion
* Solar sail

Other|

* Interstellar travel
* Propellant depot
* Laser communication in space

Transport|

| Aerial|

* Adaptive compliant wing
* Backpack helicopter
* Delivery drone
* Flying car
* High-altitude platform
* Jet pack
* Pulse detonation engine
* Scramjet
* Spaceplane
* Supersonic transport

|

Land|

* Airless tire
* Alternative fuel vehicle
* Hydrogen vehicle
* Driverless car
* Ground effect train
* Hyperloop
* Maglev train
* Personal rapid transit
* Transit Elevated Bus
* Vactrain
* Vehicular communication systems

Pipeline|

* Pneumatic transport
* Automated vacuum collection

Other|

* Anti-gravity
* Cloak of invisibility
* Digital scent technology
* Force field
* Plasma window
* Immersive virtual reality
* Magnetic refrigeration
* Phased-array optics

Topics|

* Collingridge dilemma
* Differential technological development
* Disruptive Innovation
* Ephemeralization
* Exploratory engineering
* Fictional technology
* Proactionary principle
* Technological change
* Technological unemployment
* Technological convergence
* Technological evolution
* Technological paradigm
* Technology forecasting
* Accelerating change
* Moore's law
* Technological singularity
* Technology scouting
* Technology readiness level
* Technology roadmap
* Transhumanism

* Category
* List

* v
* t
* e

Quantum mechanics

Background|

* Introduction
* History
* timeline
* Glossary
* Classical mechanics
* Old quantum theory

Fundamentals|

* Bra–ket notation
* Casimir effect
* Complementarity
* Density matrix
* Energy level
* ground state
* excited state
* degenerate levels
* Vacuum state
* Zero-point energy
* QED vacuum
* QCD vacuum
* Hamiltonian
* Operator
* Quantum coherence
* Quantum decoherence
* Measurement
* Quantum
* Quantum realm
* Quantum system
* Quantum state
* Quantum number
* Quantum entanglement
* Quantum superposition
* Quantum nonlocality
* Quantum tunnelling
* Quantum levitation
* Quantum fluctuation
* Quantum annealing
* Quantum foam
* Quantum noise
* Heisenberg uncertainty principle
* Spontaneous parametric down-conversion
* Von Neumann entropy
* Spin
* Scattering theory
* Symmetry in quantum mechanics
* Symmetry breaking
* Spontaneous symmetry breaking
* Wave propagation
* Quantum interference
* Wave function
* Wave function collapse
* Wave–particle duality
* Matter wave
* Qubit
* Qutrit
* Observable
* Probability distribution

Formulations|

* Formulations
* Heisenberg
* Interaction
* Matrix mechanics
* Schrödinger
* Path integral formulation
* Phase space

Equations|

* Dirac
* Klein–Gordon
* Pauli
* Rydberg
* Schrödinger

Interpretations|

* Interpretations
* Bayesian
* Consistent histories
* Copenhagen
* de Broglie–Bohm
* Ensemble
* Hidden variables
* Many worlds
* Objective collapse
* Quantum logic
* Relational
* Stochastic
* Transactional
* Cosmological

Experiments|

* Afshar
* Bell's inequality
* Cold Atom Laboratory
* Davisson–Germer
* Delayed-choice quantum eraser
* Double-slit
* Franck–Hertz experiment
* Leggett–Garg inequality
* Mach-Zehnder inter.
* Elitzur–Vaidman
* Popper
* Quantum eraser
* Schrödinger's cat
* Quantum suicide and immortality
* Stern–Gerlach
* Wheeler's delayed choice

Science|

* Q-analog
* List
* Quantum algebra
* Quantum calculus
* Quantum differential calculus
* Quantum geometry
* Quantum group
* Quantum Bayesianism
* Quantum biology
* Quantum chemistry
* Quantum chaos
* Quantum cognition
* Quantum cosmology
* Quantum dynamics
* Quantum economics
* Quantum evolution
* Quantum finance
* Quantum game theory
* Quantum measurement problem
* Quantum mind
* Quantum probability
* Quantum social science
* Quantum stochastic calculus
* Quantum spacetime

Technology|

* Quantum algorithms
* Quantum amplifier
* Quantum cellular automata
* Quantum finite automata
* Quantum electronics
* Quantum logic gates
* Quantum clock
* Quantum channel
* Quantum bus
* Quantum circuit
* Phase qubit
* Matrix isolation
* Quantum dot
* Quantum dot display
* Quantum dot solar cell
* Quantum dot cellular automaton
* Quantum dot single-photon source
* Quantum dot laser
* Quantum well
* Quantum computing
* Timeline
* Quantum cryptography
* Post-quantum cryptography
* Quantum error correction
* Quantum imaging
* Quantum image processing
* Quantum information
* Quantum key distribution
* Quantum machine
* Quantum machine learning
* Quantum metamaterial
* Quantum metrology
* Quantum network
* Quantum neural network
* Quantum optics
* Quantum programming
* Quantum sensors
* Quantum simulator
* Quantum teleportation
* Quantum levitation
* Time travel
* Quantum complexity theory

Extensions|

* Quantum statistical mechanics
* Relativistic quantum mechanics
* Quantum field theory
* Axiomatic quantum field theory
* Quantum field theory in curved spacetime
* Thermal quantum field theory
* Topological quantum field theory
* Local quantum field theory
* Conformal field theory
* Two-dimensional conformal field theory
* Liouville field theory
* History
* Quantum gravity

* Category
* Physics Portal
* Physics WikiProject
* Commons

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Quantum dot. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Physics:Quantum_dot&oldid=2931389"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template