Thin film microcells for concentrated applications

Miniaturizing concentrator cells is beneficial for heat and spreading resistance losses management. With III-V materials, solar cells cannot be designed much less than 0.1 mm² due to edge recombination. We study thin film Cu(In, Ga)Se2 microcells, where the diffusion length is around 1 μm. Thus small devices (<;10^-5 cm²) perform well, and the benefits of miniaturization can be exploited throughoufully. A 5% absolute efficiency increase on Cu(In, Ga)Se2 microcells at 475 suns is observed. Voc increases up to several thousand suns, temperature increment stays under 20°C at 1000 suns. Features of the high illumination regime are highlighted and modeled.