Inclusion of Water in Cu(In, Ga)Se2 Absorber Material During Accelerated Lifetime Testing

To determine if Cu(In, Ga)Se₂ (CIGS) can be submitted to the constraints that will be imposed on the solar materials of the future by an ever growing demand and necessity, we produced ultrathin (500 nm) single-stage co-evaporated CIGS solar cells doped with varying amounts and types of alkali atoms. We subjected them to accelerated lifetime testing. In the present work, we observed the seeping of water into the grain boundaries which could be identified as one of the main culprits for performance degradation. In addition, this phenomenon could only be observed when alkali atoms were present in the absorber layer.