Electrical characterization of CIGSe solar cells metastability with Zn(S,O,OH)–ZnMgO interface buffer layers

We have studied ZnO:Al/ZnMgO/Zn(S,O,OH)/Cu(In,Ga)Se2 solar cell (SC) metastability appearing during the measurement of its photovoltaic (PV) performances under AM 1.5 conditions, that is an increase with time of the PV parameters values before saturation, after about 20 min. These maximum values are not definitive since the SC returns to its initial state after about several hours. C–V profiling performed before and after the SC illumination exhibits a light soaking assisted charge redistribution within the absorber. This redistribution has been improved by thermal annealing at 200 °C. This improvement is correlated with a decrease in defects density, measured with sub-gap photocurrent.