UK student helps solve selenium solar puzzle

Led by Loughborough University PhD student Tom Fiducia, the work sought to establish the mechanism by which selenium enhanced the performance of cadmium telluride (CdTe) solar panels. According to the paper, which appears in Nature Energy, CdTe panels currently produce the cheapest form of solar available, undercutting hydrocarbons in many parts of the world.

Alloying selenium into the CdTe absorber has taken cell efficiency from 19.5 per cent to its current record of 22.1 per cent. It was previously known that the presence of selenium helped reduce the bandgap of the absorber material, increasing the cell short-circuit current, but this did not fully explain the efficiency gains. However, by measuring how much light was emitted from the panels, the team was able to solve the puzzle. Selenium enables higher luminescence efficiency and longer diffusion lengths in the alloyed material, overcoming critical defects in the bulk of the absorber layer.