Synergistic Field-Effect and Chemical Passivation for Sb2Se3 Solar Cells.

Sb2Se3 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 Sb2Se3 absorber, enhancing built-in electric field and in turn suppressing interfacial recombination. Meanwhile, we further exploit a mixed CS2 and n-butylamine to treat the Sb2Se3 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 Sb2Se3 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 Sb2Se3 solar cells.