Dual-Ion Directed Synergistic Doping for Regulating Film Crystallization and Carrier Dynamics in High-Efficiency Antimony Selenosulfide Thin-Film Solar Cells

Abstract

Antimony selenosulfide (Sb2(S,Se)3) has attracted significant attention in photovoltaic applications due to its excellent optoelectronic properties. However, despite the recent progress, the efficiency of Sb2(S,Se)3 thin-film solar cells remains significantly lower than the theoretical limit. Reducing carrier recombination and enhancing crystal orientation-induced carrier transport is crucial to further improving device performance. In this study, a novel dual-ion synergistic regulation strategy based on interface passivation layer soaking modification is employed to enhance the crystallization and crystal orientation of Sb2(S,Se)3 thin films. The results demonstrate that soaking and modifying the aluminum oxide (Al2O3) interfacial layer with a sodium hydroxide (NaOH) solution effectively reduces the oxygen content on the cadmium sulfide (CdS) surface, thereby suppressing oxygen-induced [hk0] crystal orientation growth in Sb2(S,Se)3 thin films. Moreover, for the first time, this study reveals that the synergistic doping of Na and Al ions regulates the crystallization kinetics of Sb2(S,Se)3, leading to improve carrier transport, reduce deep-level defect density, and optimize band structure, ultimately suppressing carrier recombination. As a result, a Sb2(S,Se)3 thin-film solar cell with an efficiency of 9.79% is achieved under this dual-ion synergistic regulation strategy.