(390d) Double Cation Substitution of CZTS Chalcogenide Semiconductors for Improved Device Performance

Solution processed thin-film photovoltaic (PV) technology is poised to be the future of manufacturing standard for commercially available solar energy modules due to the substantially low estimated capital expenditure (CAPEX) required. Over the decades, the concept of high efficiency CZTSSe has enticed researchers but always eluded their grasps. This report explores improving the device performance metrics of CZTSSe with the goal of improving the PCE in hopes that it become industrially disruptive to the currently adopted technologies. The approach taken in this research was to conduct double cation alloying with elements shown in literature to have beneficial impacts for CZTSSe device performance with the hypothesis that the combination would be complementary. First, we investigated the combination of small stoichiometric substitutions of Cu with Ag and Zn with Mn so that the resulting stoichiometry would resemble (Agx,Cu1-x)2(MnyZn1-y)Sn(S,Se)4. Second we investigated the double cation substitution of Cu with Ag and Sn with Ge so that the already proven effects of Ge incorporation could be correlated with the effects of Ag. Collectively, the work included in this report demonstrates considerable progress exploring uncharted avenues toward increasing the performance of CZTSSe. By attempting a new approach to understanding optoelectronic performance and reliability in CZTSSe the goal of high efficiency CZTSSe may soon be attainable.