A study of the degradation mechanisms of ultra-thin CIGS solar cells submitted to a damp heat environment

Producing the green energy of tomorrow will require highly efficient as well as energy-, and cost-effective solar cells in addition to having reasonable lifetimes. To determine if CIGS can be made to submit to these constraints, we produced ultra-thin (500nm) single-stage coevaporated CIGS solar cells. We doped these cells with varying amounts and types of alkali atoms and submitted them to accelerated lifetime testing. Results showed definite effect of the alkali concentration on the degradation of the cells but showed limited migration. Instead, the seeping of water into the grain boundaries was identified as the main culprit for performance degradation.