Synergistic Field‐Effect and Chemical Passivation for Sb 2 Se 3 Solar Cells

Sb 2 Se 3 is a promising thin‐film photovoltaic absorber, yet its performance is limited by severe nonradiative recombination originating from interfacial and bulk defects. Here, we address this challenge by developing a synergistic passivation strategy that combines interfacial field‐effect modulation with bulk chemical treatment. Indium doping is introduced into the CdS electron transport layer to increase carrier concentration, inducing energy band bending within the Sb 2 Se 3 absorber, enhancing built‐in electric field and in turn suppressing interfacial recombination. Meanwhile, we further exploit a mixed CS 2 and n‐butylamine to treat the Sb 2 Se 3 absorber through which this treatment is able to effectively reduce deep‐level defect density, particularly selenium‐vacancy‐related electron traps, and improve carrier lifetime. The combined effects lead to reduced trap‐assisted recombination, and more efficient charge separation. As a result, the optimized Sb 2 Se 3 solar cells achieve a top power conversion efficiency of 8.82%, with an open‐circuit voltage of 457 mV, a fill factor of 63.0% and a short‐circuit current density of 30.64 mA cm −2 . This study provides an effective strategy for mitigating nonradiative recombination and advancing the performance of Sb 2 Se 3 solar cells.