Sun-free photovoltaics

Sun-free photovoltaics is a photovoltaics technology which does not require sunlight to produce electricity.[1] This technique was developed by research team at Massachusetts Institute of Technology.[2] Photovoltaic cells convert light to electricity most efficiently at specific wavelengths.[3][4] The surface features of Sun-free photovoltaics is engineered such that it converts heat energy into the specific wavelengths.[5] This increases the efficiency of existing thermophotovoltaic (TPV) systems.[6]

## Contents

* 1 Principle of working
* 2 Development
* 3 Operation
* 4 Applications
* 5 References
* 6 See also

## Principle of working

The surface of this material is etched with billions of nanoscale pits, so that it emits wave at the specified wavelengths[2][6] and suppresses other wavelengths which are not required.[6] When the surface is exposed to heat energy, it radiates light energy at required wavelengths.[7] The atoms liberates free electrons when radiation is applied, thus generating electricity.[8]

## Development

A device that uses radioisotopes is capable of producing electricity for up to 30 years without interruption using a process called radioactive decay.[2] Another similar device was developed by researchers from MIT, which uses butane as a fuel source. It has the size of a button and is estimated to operate three times longer than a similarly sized lithium-ion battery[5] and has the advantage of recharging immediately upon refuelling.[1] Thermo-photovoltaics, which is a technology developed in the 1960s, is capable of converting heat energy into electricity.[1] It was previously known that sunlight is not absolutely necessary for photovoltaic cells to operate.[3] Infrared radiation is not utilized efficiently in photovoltaic materials which are characterized by low band gap,[5] though the performance is comparatively better than normal silicon photovoltaic cells.[4] One example of photovoltaics utilizing heat is a photovoltaic diode which produces electricity from heat given off by a hydrocarbon fuelled thermal emitter.[1][9]

In Sun-free photovoltaics, the thermal emitter described above is finely tuned to emit specific wavelengths that the photovoltaic diode can utilize, while at the same time stopping the wavelengths that cannot be used by the diode.[4] This is achieved by etching features of nanoscale like ridges and holes on a photonic crystal[3] so that the light passing through the crystal can be modified.[1]

## Operation

A slab of tungsten[8] is used as a thermal emitter with billions of nanoscale pits on the surface,[1] with each pit acting like a resonator.[3] On heating, specific wavelengths are radiated by the slab as it generates an altered emission spectrum.[3]

## Applications

Sun-free photovoltaics can be applied in electronic devices like smartphones. Its value of current density has the capability to be tripled in the coming years, when it could power a smartphone for more than 20 days without needing to recharge in between.[5] It can also be used to utilize waste heat from electric appliances like televisions and electronic appliances like mobile phones.[2][8]

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "Sun-free photovoltaics - Materials engineered to give off precisely tuned wavelengths of light when heated are key to new high-efficiency genserating system.". Massachusetts Institute of Technology. 28 July 2011. http://web.mit.edu/newsoffice/2011/sun-free-photovoltaics-0728.html. Retrieved 2011-08-08.
2. ↑ 2.0 2.1 2.2 2.3 "PHOTOVOLTAIC ELECTRICITY GENERATION WITHOUT SUNLIGHT". Electronics News. http://www.electronicsnews.com.au/news/photovoltaic-electricity-generation-without-sunlig. Retrieved 2011-08-10.
3. ↑ 3.0 3.1 3.2 3.3 3.4 "Sun-Free Photovoltaics: Materials Engineered to Give Off Precisely Tuned Wavelengths of Light When Heated". sciencedaily.com. https://www.sciencedaily.com/releases/2011/07/110730180245.htm. Retrieved 2011-08-08.
4. ↑ 4.0 4.1 4.2 "Sun-free photovoltaics". nanowerk.com. http://www.nanowerk.com/news/newsid=22248.php. Retrieved 2011-08-08.
5. ↑ 5.0 5.1 5.2 5.3 "Sun-free photovoltaics". physorg.com. http://www.physorg.com/news/2011-07-sun-free-photovoltaics.html. Retrieved 2011-08-08.
6. ↑ 6.0 6.1 6.2 "MIT reports breakthrough in heat-based photovoltaics". gizmag.com. 2 August 2011. http://www.gizmag.com/sun-free-photovoltaics/19393/. Retrieved 2011-08-08.
7. ↑ ""Sun-Free" Photovoltaics!". crazyengineers.com. http://www.crazyengineers.com/sun-free-photovoltaics-699/. Retrieved 2011-08-08.
8. ↑ 8.0 8.1 8.2 "Solar cells need no sun, just heat to create energy - Promising new technology can turn nearly anything hot into a power source". MSN. 2 August 2011. http://www.nbcnews.com/id/43989608. Retrieved 2011-08-10.
9. ↑ Free Electricity Generator

## See also

* Quantum efficiency of a solar cell
* Energy conversion efficiency
* Photoelectric effect
* Solar cell efficiency

* v
* t
* e

Photovoltaics

Concepts|

| Technology|

* Photovoltaics
* Photoelectric effect
* Solar insolation
* Solar constant
* Solar cell efficiency
* Quantum efficiency
* Nominal power (Watt-peak)
* Thin-film solar cell
* Multi-junction solar cell
* Third-generation photovoltaic cell
* Solar cell research
* Thermophotovoltaic
* Thermodynamic efficiency limit
* Sun-free photovoltaics
* Polarizing organic photovoltaics

|

Materials|

* List of semiconductor materials
* Crystalline silicon (c-Si)
* Polycrystalline silicon (multi-Si)
* Monocrystalline silicon (mono-Si)
* Cadmium telluride
* Copper indium gallium selenide
* Amorphous silicon (a-Si)

History|

* Growth of photovoltaics
* Timeline of solar cells

Photovoltaic system|

| Solar cells|

* Nanocrystal solar cell
* Organic solar cell
* Quantum dot solar cell
* Hybrid solar cell
* Plasmonic solar cell
* Carbon nanotubes in photovoltaics
* Dye-sensitized solar cell
* Cadmium telluride photovoltaics
* Copper indium gallium selenide solar cells
* Printed solar panel
* Perovskite solar cell

|

System components|

* Solar panel
* Balance of system
* Solar charge controller
* Solar inverter
* Solar micro-inverter
* Solar cable
* Photovoltaic mounting system
* Maximum power point tracker
* Solar tracker
* Solar shingles
* Solar mirror
* Synchronverter

System concepts|

* Perturb and observe method
* Incremental conductance method
* Constant voltage method
* Fill factor
* Concentrated photovoltaics
* Photovoltaic thermal hybrid solar collector
* Space-based solar power

Applications|

| Appliances|

* Solar-powered refrigerator
* Solar air conditioning
* Solar lamp
* Solar charger
* Solar backpack
* Solar tree
* Solar-powered pump
* Solar-powered watch
* Solar Tuki
* Photovoltaic keyboard
* Solar road stud
* Solar cell phone charger
* Solar notebook
* Solar-powered calculator
* Solar-powered fountain
* Solar-powered radio
* Solar-powered flashlight
* Solar-powered fan
* Solar street light
* Solar traffic light

|

Land transport|

* Solar vehicle
* Solar car
* Solar roadway
* Solar golf cart
* The Quiet Achiever
* Sunmobile

Air transport|

* Electric aircraft
* Mauro Solar Riser
* Solar panels on spacecraft
* Solar-Powered Aircraft Developments Solar One
* Gossamer Penguin
* Qinetiq Zephyr
* Solar Challenger

Water transport|

* Solar boat

Solar vehicle racing|

* Solar car racing
* List of solar car teams
* Solar challenges
* World Solar Challenge
* American Solar Challenge
* Formula Sun Grand Prix
* Solar Cup
* Frisian Solar Challenge
* Solar Splash
* South African Solar Challenge
* Tour de Sol
* Hunt-Winston School Solar Car Challenge
* Victorian Model Solar Vehicle Challenge

Generation systems|

| PV power station|

* Grid-connected photovoltaic power system
* List of photovoltaic power stations

|

Individual projects|

* Alamosa photovoltaic power plant
* Beneixama photovoltaic power plant
* Blythe Photovoltaic Power Plant
* Copper Mountain Solar Facility
* Darro Solar Park
* Erlasee Solar Park
* Golmud Solar Park
* Gottelborn Solar Park
* Guadarranque solar power plant
* Köthen Solar Park
* Moura Photovoltaic Power Station
* Olmedilla Photovoltaic Park
* Pocking Solar Park
* Puertollano Photovoltaic Park
* Topaz Solar Farm
* Wyandot Solar Facility

Building-mounted|

* Rooftop photovoltaic power station
* Building-integrated photovoltaics
* Solar Ark
* Strasskirchen Solar Park

By country|

* Australia
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* Czech Republic
* France
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* Greece
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* Netherlands
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* United Kingdom
* USA

PV companies|

| By country|

* List of countries by photovoltaics production

|

Individual producers|

* First Solar
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* Motech Solar
* REC
* Sharp
* Solar Frontier
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* Sungen Solar
* Sunpower
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* Trina Solar
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* Category
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