Inclusion of Water in Cu(In, Ga)Se 2 Absorber Material During Accelerated Lifetime Testing

To determine if Cu(In, Ga)Se-2 (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 coevaporated 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. This work received funding from the European Union’s H2020 research and innovation program under grant agreement 715027. We acknowledge the use of a LEAP 5000 HR at APT Flanders, KU Leuven (Hercules Foundation under contract ZW/13/09)