Enhanced Performance of CdTe Solar Cells with Sb2Se3 Back Contacts

The barrier at CdTe/metal interface severely limits the efficiency of CdTe photovoltaic devices. Herein, the effectiveness of a thermally evaporated Sb2Se3 buffer layer as a back contact in CdTe solar cells is investigated, revealing a significant enhancement in device performance. Through optimization of Sb2Se3 thickness, a remarkable increase in the open-circuit voltage (V-OC) to 804 mV is achieved, leading to a substantial efficiency improvement of 12.84% when compared to the Au-only back contact device. X-ray photoelectron spectroscopy (XPS) reveals a well-matched energy band alignment at CdTe/Sb2Se3 interface, confirming favorable conditions for hole transport. To further enhance the device performance, Cu doping is implemented in the Sb2Se3 film, resulting in additional improvements to the V-OC and fill factor (FF) of the Cu-doped configuration to 819 mV and 72.35%, respectively, while also enhancing the overall efficiency to 14.3%.