New research from scientists at the University of California, Berkeley (UC Berkeley) has demonstrated that for maximum efficiency, solar cells might be designed to be similar to light-emitting devices (LEDs).
‘What we demonstrated is that the better a solar cell is at emitting photons, the higher its voltage and the greater the efficiency it can produce,’ says Eli Yablonovitch, principal researcher and UC Berkeley professor of electrical engineering.
Recently, Yablonovitch and his colleagues were trying to understand why there has been such a large gap between the theoretical limit and the limit that researchers have been able to achieve. They came across a solution based on a mathematical connection between absorption and emission of light.
Designing solar cells to emit light – so that photons do not become ‘lost’ within a cell – has the natural effect of increasing the voltage produced by the solar cell, according to the scientists.
PV manufacturer Alta Devices, co-founded by Yablonovitch, has used the concept to create a prototype solar cell made of gallium arsenide (GaAs). The prototype broke efficiency records, according to UC Berkeley. The company achieved this milestone, in part, by designing the cell to allow light to escape as easily as possible from the cell.
Yablonovitch says efficiencies close to 30% may be possible in the coming years. The research team plans to present its findings May 11 at the Conference on Lasers and Electro-Optics in San Jose, Calif.