Perovskite solar cells upgraded
A sample all-inorganic perovskite solar cell is a step towards toward commercial use, according to scientists at Rice University. Their discovery of a way to quench defects in cesium-lead-iodide solar cells allowed them to preserve the material’s band gap. Image credit: Jeff Fitlow/Rice University
By Anthony Caggiano
Rice University scientists have replaced some of the lead in perovskite solar cells with indium, which could help improve their performance.
Rice materials scientist Jun Lou and his colleagues at the Brown School of Engineering have been able to better manage defects in cesium-lead-iodide solar cells that affect the compound's band gap, a critical property in solar cell efficiency.
The cells can also be made in open air and last for months rather than days with a solar conversion efficiency slightly above 12%.
Traditionally, materials used in perovskites - crystals with cube-like lattices and are efficient light harvesters – tend to be stressed by light, humidity and heat.
Rice postdoctoral researcher and lead author Jia Liang and his team built and tested perovskite solar cells of inorganic cesium, lead and iodide, the very cells that tend to fail quickly due to defects. But by adding bromine and indium, the researchers were able to quash defects in the material, raising the efficiency above 12% and the voltage to 1.20 volts.
As a bonus, the material proved to be exceptionally stable. The cells were prepared in ambient conditions, standing up to Houston's high humidity, and encapsulated cells remained stable in air for more than two months, far better than the few days that plain cesium-lead-iodide cells lasted.
‘The highest efficiency for this material may be about 20%, and if we can get there, this can be a commercial product,’ Liang said. ‘It has advantages over silicon-based solar cells because synthesis is very cheap, it's solution-based and easy to scale up. Basically, you just spread it on a substrate, let it dry out, and you have your solar cell.’
