Thin film solar cells made from cadmium telluride have a significant advantage over conventional solar cells made from crystalline silicon. They need far less raw material — up to 100 times less — which makes them cheaper to manufacture than silicon cells. They also absorb sunlight at nearly the ideal wavelength. As a result, electricity generated by thin film solar cells is the least expensive available today.
Thin film solar has one significant disadvantage, however. It is less efficient at converting sunlight into electricity than silicon wafers. Researchers at Colorado State University Next Generation Photovoltaics Center, working in collaboration with scientists at Loughborough University in the United Kingdom, have discovered that adding selenium to the mix can boost thin film solar’s efficiency to around 22% — as good as some of the best silicon wafer solar cells.
The question the scientists couldn’t answer was why adding selenium to the mix made the thin film cells more efficient. Their experiments revealed that selenium overcomes the effects of atomic-scale defects in the cadmium telluride crystals. Electrons generated when sunlight hits the selenium-treated solar panel are less likely to be trapped and lost in the defects often located at the boundaries between crystal grains as they are grown, increasing the amount of power extracted from each solar cell in the process. The results of the research were published recently in the journal Nature Energy.
Okay, this is only in the laboratory phase right now. We all know there is no guarantee breakthroughs in the lab will ever translate into commercially viable products. But this research, funded in part by National Science Foundation, is precisely the kind of thing that keeps driving down the price of solar energy and making it harder for fossil fuels to compete.
The key to decarbonizing electricity generation is continuing to find ways of beating fossil fuels on price without subsidies. Selenium enriched thin film solar could help put the fossil fuel companies out of business.