Carrier Transport Enhancement Mechanism in Highly Efficient Antimony Selenide Thin‐Film Solar Cell

Abstract Exhibiting outstanding optoelectronic properties, antimony selenide (Sb 2 Se 3 ) has attracted considerable interest and has been developed as a light absorber layer for thin‐film solar cells over the decade. However, current state‐of‐the‐art Sb 2 Se 3 devices suffer from unsatisfactory “cliff‐like” band alignment and severe interface recombination loss, which deteriorates device performance. In this study, the heterojunction interface of an Sb 2 Se 3 solar cell is improved by introducing effective aluminum (Al 3+ ) cation into the CdS buffer layer. Then, the energy band alignment of Sb 2 Se 3 /CdS:Al heterojunction is modified from a “cliff‐like” structure to a “spike‐like” structure. Finally, heterojunction interface engineering suppresses recombination losses and strengthens carrier transport, resulting in a high efficiency of 8.41% for the substrate‐structured Sb 2 Se 3 solar cell. This study proposes a facile strategy for interfacial treatment and elucidates the related carrier transport enhancement mechanism, paving a bright avenue to overcome the efficiency bottleneck of Sb 2 Se 3 thin‐film solar cells.