Hot Electrons Could Double Solar Cell Power Efficiency

Dec 18, 2009 by Lisa Zyga weblog
Hot electron solar cell
Hot electrons could pass through an ultra-thin solar cell without cooling down, with the potential for doubling solar cell efficiency. Image credit: Michael Naughton.

Scientists have experimentally verified a theory suggesting that hot electrons could double the output of solar cells. The researchers, from Boston College, have built solar cells that successfully use hot electrons to increase the cells' power ouput. Although the power increase is small, the concept could lead to solar cells that break conventional efficiency limits.

Michael Naughton, a physics professor at Boston College, and others have designed an ultra-thin (15-nanometer-thick) solar cell, which hot electrons can quickly pass through before cooling. In conventional, thicker , only the "cooler" lower-energy electrons that have longer wavelengths can pass through.

When a conventional solar cell absorbs a high-energy photon, it produces a hot electron that quickly loses much of its energy as heat before it can pass through the cell and be used to generate electricity. Although solar cells can be designed to absorb high-energy photons and use hot electrons, they aren't able to absorb low-energy photons as well. The new solar cell design, however, can absorb both.

Theoretically, solar cells that can absorb hot and cool electrons could nearly double their . Conventional solar cells can convert at most about 35% of sunlight energy into electricity, and the rest is wasted as heat. By absorbing the hot electrons, solar cells could achieve efficiencies of up to 67%, according to an article in MIT's Technology Review. By doubling the efficiency, the cost of solar power could be cut in half.

There are still challenges with the new ultra-thin solar cells, however. Because they're so thin, most of the light passes through them, so they only convert about 3% of incoming light into electricity. But past research has shown that adding to the could allow them to absorb more light while still keeping a short travel distance for the electrons. In addition, the scientists are investigating incorporating into the to increase the number of electrons collected from the absorbed light.

Explore further: Study reveals new characteristics of complex oxide surfaces

More information: Elusive 'hot' electrons captured in ultra-thin solar cells

add to favorites email to friend print save as pdf

Related Stories

Elusive 'hot' electrons captured in ultra-thin solar cells

Dec 11, 2009

Boston College researchers have observed the "hot electron" effect in a solar cell for the first time and successfully harvested the elusive charges using ultra-thin solar cells, opening a potential avenue to improved solar ...

Greatly Improved Solar Cells

Apr 21, 2004

Victor Klimov and Richard Schaller at Los Alamos National Laboratory have enhanced the phenomenon called "impact ionization," which can significantly improve the efficiency of the conversion of solar energy to ...

Quantum Dots Could Boost Solar Cell Efficiency

Mar 11, 2009

(PhysOrg.com) -- The transition to environmentally benign energy sources is one of the most significant challenges of the 21st century. Solar power, which uses sunlight to generate electricity, is one promising source. It ...

Solar cells of the future

Dec 18, 2007

A new material, nano flakes, may revolutionise the transformation of solar energy to electricity. If so, even ordinary households can benefit from solar electricity and save money in the future.

Silver Nanoparticles Give Polymer Solar Cells A Boost

Oct 05, 2009

(PhysOrg.com) -- Small bits of metal may play a new role in solar power. Researchers at Ohio State University are experimenting with polymer semiconductors that absorb the sun’s energy and generate electricity. The goal: ...

Recommended for you

A crystal wedding in the nanocosmos

Jul 23, 2014

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Vienna University of Technology and the Maria Curie-Skłodowska University Lublin have succeeded in embedding nearly perfect semiconductor ...

PPPL studies plasma's role in synthesizing nanoparticles

Jul 22, 2014

DOE's Princeton Plasma Physics Laboratory (PPPL) has received some $4.3 million of DOE Office of Science funding, over three years, to develop an increased understanding of the role of plasma in the synthesis ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

sender
3 / 5 (1) Dec 18, 2009
maybe capturing 100% of the photonic energy requires a non-blinking brewster prism array, hopefully some scientist will read this comment and build the patent for it :)
Parsec
3 / 5 (1) Dec 19, 2009
Actually, the trick is probably to create a stack of these ultra thin cells. Each layer absorbs some photons and passes the rest thru, until all the light is absorbed and converted into electricity. It would be essential of course to have a very inexpensive manufacturing process so that the stacks wouldn't have to be created one layer at a time, but I don't see why epitaxial growth processes along with diffusion sputtering used for normal silicon manufacturing couldn't be used.