High-performance antimony selenide solar cells enabled by in situ potassium doping

Abstract

Solar cells, serving as the core technology for solar energy conversion, have witnessed remarkable progress in recent years. Among various materials, the emerging photovoltaic material antimony selenide (Sb₂Se₃) has gradually become a research hotspot due to its advantages, such as the abundance of raw materials, excellent optical properties, and a simple preparation process. The fabrication of absorber layer films with large grains and low defects is crucial for achieving high-efficiency devices. To enhance device efficiency, this study introduces an in situ potassium (K) doping approach by incorporating KCl into the precursor solution during the chemical bath deposition (CBD) of Sb₂Se₃ films, with the goal of refining film morphology and defect characteristics. Structural and compositional analyses reveal that the doping occurs in the form of K–Se chemical bonds at the surface and grain boundaries of the Sb₂Se₃ films. After KCl doping, the quality of the Sb₂Se₃ films is improved, with a more uniform and compact surface morphology, increased grain sizes, enhanced crystal growth orientation, and reduced film defects. Ultimately, the power conversion efficiency (PCE) of the FTO/CdS/Sb₂Se₃/Spiro-OMeTAD/Au structured device was enhanced to 8.56%, marking an approximate 12% improvement over that of the control device. This performance ranks it among the high-efficiency Sb₂Se₃ devices fabricated via the CBD method. This study provides a new approach for enhancing the quality of Sb₂Se₃ films and device efficiency from a doping perspective, laying the foundation for further research and development of this material.