Rapid Thermal Selenization Enhanced Efficiency in Sb₂Se₃ Thin Film Solar Cells with Superstrate Configuration

Antimony selenide (Sb₂Se₃) is a promising material for solar energy conversion due to its low toxicity, high stability, and excellent light absorption capabilities. However, Sb₂Se₃ films produced via physical vapor deposition often exhibit Se-deficient surfaces, which result in a high carrier recombination and poor device performance. The conventional selenization process was used to address selenium loss in Sb₂Se₃ solar cells with a substrate configuration. However, this traditional selenization method is not suitable for superstrated Sb₂Se₃ devices with the window layer buried underneath the Sb₂Se₃ light absorber layer, as it can lead to significant diffusion of the window layer material into Sb₂Se₃ and damage the device. In this work, we have demonstrated a rapid thermal selenization (RTS) technique that can effectively selenize the Sb₂Se₃ absorber layer while preventing the S diffusion from the buried CdS window layer into the Sb₂Se₃ absorber layer. The RTS technique significantly reduces carrier recombination loss and carrier transport resistance and can achieve the highest efficiency of 8.25%. Overall, the RTS method presents a promising approach for enhancing low-dimensional chalcogenide thin films for emerging superstrate chalcogenide solar cell applications.