rGO-regulated chemical bath deposition of Sb2S3 thin films for outdoor and indoor photovoltaics

Antimony sulfide (Sb 2 S 3 ) is a promising absorber for photovoltaics operating under both outdoor and indoor illumination due to its suitable bandgap and excellent photostability. However, during chemical bath deposition, the unsynchronized hydrolysis and sulfidation of Sb 3+ species induce excessive homogeneous nucleation, leading to amorphous particles and ultimately films with small grains, high grain boundary density, and low crystallinity. To address this issue, an rGO-regulated deposition strategy is developed. The oxygen-containing functional groups on rGO can interact with Sb 3+ species through coordination and electrostatic interactions, thereby modulating their local availability and reaction kinetics. This suppresses homogeneous nucleation and promotes substrate-guided growth, yielding Sb 2 S 3 films with [ hk 1] preferred orientation, enlarged grains, reduced defects, and improved carrier transport. As a result, the photovoltaic device with rGO-regulated achieves a PCE of 7.61% under AM 1.5G illumination (compared to 7.15% for the conventional CBD device) and 17.64% under 3000 K, 1000 lux warm white LED illumination. This work highlights Sb 2 S 3 as a versatile absorber for outdoor–indoor photovoltaics and provides a pathway for regulating solution-phase crystallization.