In situ polymerization-assisted grain growth of Sb2(S,Se)3 on Cd-free TiO2 for efficient solar cells

Antimony selenosulfide (Sb 2 (S,Se) 3 ) demonstrates strong potential for thin-film solar cells owing to its tunable bandgap, low toxicity, and high stability. However, conventional fabrication methods often yield films with small grain sizes and random orientations, which hinder device performance. Herein, an in situ polymerization-assisted grain growth (iPAGG) strategy was developed, specifically enabling the oriented growth of Sb 2 (S,Se) 3 on Cd-free TiO 2 substrates, by introducing acrylic acid (AA) into the chemical bath deposition process. The carboxylate groups from AA coordinate with Sb 3+ ions, promoting oriented growth of Sb 2 (S,Se) 3 film. This approach yields films with enlarged grains, reduced defect densities, and strengthened [ hk 1] preferred orientation. As a result, Cd-free Sb 2 (S,Se) 3 solar cells employing the optimized AA concentration yielded a champion power conversion efficiency (PCE) of 7.24%, outperforming the control device (6.70%). Further interfacial modification with poly (acrylic acid)-modified SnO 2 boosts the PCE to 7.55%. This work offers an effective way toward the fabrication of high-performance and environmentally friendly Sb 2 (S,Se) 3 photovoltaics.