Enhancing the Efficiency of CZTSSe Solar Cells by Cation Alloying

We can address the serious issues of fuel depletion and climate change that require urgent attention by developing alternative energy sources. Solar energy is a renewable energy that can replace fossil fuel-dependent sources, as it does not produce carbon dioxide or other greenhouse, gases and is environmentally friendly. Up to now, the highest efficiency of CZTSSe thin film solar cells replace with CIGS materials achieved 14.9%, that is lower than the CIGS world record of 23.35%. Therefore, additional research is essential to enhance the efficiency needed for commercialization. We have endeavored to overcome the limitations of V_oc and <i>J</i>_sc in CZTSSe thin film solar cells via cation substitution. CZTSSe thin films have lower performance than other materials when applied to devices due to problems such as many lattice defects and secondary phase formation. To enhance this Ge and Cd were selected. CZTSSe was doped with Ge and it was replaced with Sn to reduce pinhole and bulk recombination, and CZTSSe was doped with Cd and it was replaced with Zn to promote grain growth and suppress secondary phase formation. CZTSSe thin film solar cells with Ge alloyed enhanced the V_oc by 494 mV, and CZTSSe thin film cells with Cd alloyed enhanced the <i>J</i>_sc by 36.9 mA/cm². As a results, We achieved its highest performance of 10.84%, representing a 20% enhancement compared to the pure CZTSSe device without alloying.