Comparison of metastabilities in CIGS solar cells with In2S3 and CdS buffer layers

The metastable behaviour induced by light soaking and reverse bias treatment in Cu(In, Ga)Se2 (CIGS) based solar cells with vapour deposited indium sulphide buffer layer is compared to the baseline CdS-buffered devices. The dark and light current-voltage characteristics, capacitance-voltage doping profiles and admittance spectra have been measured and the influence of light soaking and reverse bias treatment on these characteristics were investigated. While the changes induced by both treatments on charge distribution in the absorber in both types of cells were similar, only a minor impact on the photovoltaic parameters of In2S3-buffered cells was observed. Thus we conclude that In2S3 buffer is a good alternative to CdS in terms of ensuring a stable cell performance.