Heterojunction Interface Anomalous High‐Energy Level Insertion Modulating Carrier Dynamics in High‐Efficiency Antimony Selenide Thin‐Film Solar Cells

Abstract 1D antimony selenide (Sb ₂ Se ₃ ) films are commonly used as absorber layers in high‐efficiency thin‐film solar cells due to their excellent optoelectronic properties. However, the performance of Sb ₂ Se ₃ solar cells is severely limited by serious carrier recombination. Exploring effective carrier recombination and transport regulation is crucial to enhancing the performance of Sb ₂ Se ₃ solar cells. In this work, unlike previously reported conventional gradient band structures, a high‐energy‐level ultrathin amorphous tin oxide layer (SnO ₂ ) deposited by atomic layer deposition is used as an interfacial layer inserted at the cadmium sulfide (CdS)/Sb ₂ Se ₃ heterojunction. Unlike previously reported interfacial layers, the SnO ₂ interface layer does not exhibit significant ion diffusion at the heterojunction interface. Notably, the results indicate that the interfacial SnO ₂ layer can promote the [ hk 1] orientation, thereby enhancing orientation‐induced carrier transport. Furthermore, the interfacial SnO ₂ layer can significantly reduce both interfacial and bulk defects, improve interfacial carrier extraction, and decrease carrier recombination. This leads to improved carrier transport and collection. Ultimately, a high‐efficiency Sb ₂ Se ₃ solar cell with an efficiency of 9.73% is achieved based on enhanced [ hk 1] orientation, increased carrier lifetime, and optimized band alignment. This work can also provide crucial theoretical and technical support for the sustainable development of thin‐film solar cells.