Cu ₂ Sb-Based CdTe Solar Cells: The Effects of Cu and Sb Dopants on Photoelectronic Performance and Long-Term Stability of Devices

Copper doping represents the most established technological process in the current manufacturing of CdTe solar cells and modules. However, its self-compensation effect and rapid diffusion at junction locations impose limitations on both the device efficiency and long-term stability. In this study, a Cu₂Sb thin film with controllable composition and thickness was synthesized on the CdTe surface via a substitution reaction, serving as the p-type doping source for the device. Comparative investigations were conducted to evaluate the effects of pure Cu, pure Sb, and Cu-Sb alloyed dopants on the photoelectronic performance of CdTe-based thin-film solar cells. Although pure Sb dopants exhibit inferior performance and cannot replace Cu as the primary dopant, they serve effectively as auxiliary dopants. Incorporating Sb into the Cu doping process increases the concentration threshold for device doping, thereby enhancing the device's overall doping concentration. The optimized device achieved a power conversion efficiency (PCE) exceeding 18%. Furthermore, appropriate Sb incorporation significantly improved device stability, maintaining 90% of the initial PCE after 50 days of normal operation. These results demonstrate that codoping with Cu and Sb via Cu₂Sb provides a promising route for fabricating high-efficiency and highly stable CdTe thin-film solar cells and modules.