Simulation of the efficiency dependency of multi-junction photovoltaic cells based on titanium oxide and copper oxide using SCAPS software

Abstract

To advance the development of thin-film photovoltaic (PV) technologies, current research is increasingly focused on identifying alternative materials to zinc oxide (ZnO), cadmium sulfide (CdS), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). Among the most promising candidates are titanium oxide (TiO₂) and copper oxide (Cu₂O or CuO), owing to their abundance, non-toxicity, and favourable optoelectronic properties. This study presents a simulation-based investigation of a multi-junction PV structure based on n-TiO₂/p-Cu_xO single cell using the solar cell capacitance simulator (SCAPS). The multi-junction configuration offers significant efficiency advantages over single-junction cells by minimising defects associated with lattice mismatch for thinner TiO₂/Cu_xO layers in a tandem device. Reducing interface defect density through improved fabrication techniques could substantially enhance efficiency. Furthermore, in multi-junction architectures, improved carrier extraction and reduced recombination losses increase the open-circuit voltage (V_oc), thereby improving carrier transport to external contacts and enhancing cell performance.