Defect‐Tolerant Recombination Junction Enabling Enhanced <i>V</i> _OC in Sb ₂ Se ₃ Solar Cells via High‐Work‐Function Metal Oxides: A Simulation Perspective

Interfacial recombination is a key loss pathway that limits the open‐circuit voltage ( V OC ) in Sb 2 Se 3 solar cells. Conventional approaches aim to suppress interface defects. However our simulations reveal that presence of shallow acceptor‐like traps at the junction with high‐work‐function n‐type metal oxide‐based hole‐selective layer (n‐HSL) can instead enable beneficial trap‐assisted recombination. This mechanism facilitates efficient hole extraction, leading to marked improvements in V OC and fill factor. Using SCAPS‐1D, we numerically optimize Sb 2 Se 3 solar cells incorporating wide‐bandgap oxides such as WO x , V 2 O x , or MoO x , and show that performance critically depends on the interplay between interfacial defect energetics and the electron affinity ( χ n ) of the n‐HSL. Lower χ n values favor trap‐mediated recombination through shallow acceptor states, enhancing V OC , whereas higher χ n values (comparable to the ionization potential of Sb 2 Se 3 ) render the interface defect tolerant. In contrast, donor‐like defects strongly suppress V OC . These results challenge the conventional view of interface defects as purely detrimental and establish a new design principle: n‐HSL‐based defect‐enabled recombination junction can be strategically engineered to overcome the V OC deficit in Sb 2 Se 3 and related chalcogenide photovoltaics.