Correlation between physical, electrical, and optical properties of Cu2ZnSnSe4 based solar cells

We report on the physical, electrical, and optical properties of Cu2ZnSnSe4 (CZTSe) solar cells based on an absorber layer fabricated by selenization of sputtered Cu, Zn, Sn multilayers. It is shown that the doping density as measured by drive level capacitance profiling is correlated exponentially to the Zn/Sn ratio of the CZTSe absorber as measured by energy dispersive X-ray spectroscopy. Furthermore, it is shown that the open circuit voltage of the cells, minority carrier lifetime, and peak position of the photoluminescence response of the absorber all correlate with the doping level and, therefore, with the Zn/Sn ratio measured in the absorber.