Investigation of Light Induced Metastabilities through Colored Filters on CZTSSe monograin PV devices

Measurements of the photovoltaic (PV) activity of solar cells under low-light conditions using different wavelength-selective filters can provide useful information about nature, location and activation of defects, and possible recombination mechanisms inside-of CZTSSe solar cell interfaces. In this work, we use this approach for the characterization of flexible monograin membrane kesterite (CZTSSe) PV devices. Time dependence of the open circuit voltage, short circuit current, fill factor and maximum power, under low intensity of white, red and blue light is studied and related to carrier recombination processes in the bulk of the absorber and at the interface with the CdS buffer and the electrodes. The different illumination conditions cause moderate metastabilities in the electrical parameters, which are reversible when the cell is stored in dark for some hours. Reversible and irreversible contributions to the light-soaking effects are further analyzed.