Ion-modulated hydrothermal growth: A game-changing strategy for high-performance Sb2(S,Se)3 solar cells with minimized recombination losses

Sb₂(S,Se)₃ has garnered significant interest as a light-harvesting material owing to its exceptional photovoltaic properties. However, conventional hydrothermal synthesis yields Sb₂(S,Se)₃ films exhibiting detrimental energy-level inversion and high defect density (e.g., S vacancy/antisite defects) and severely limiting device performance. To address these limitations, we developed an Cs⁺ ion-modulated hydrothermal growth (IHG) strategy that eliminates programmed-temperature ramping, enabling direct construction of high-quality Sb₂(S,Se)₃ bulk heterojunctions (BHJs). This approach simultaneously enlarges grain dimensions and crystal size (0.40 μm → 0.75 μm), and enhances out-of-plane charge transport along the [hkl, l ≠ 0] orientation, effectively suppressing reversed unfavorable Se-gradients distribution while passivating deep-level defects of Sb₂(S,Se)₃ films. Ultimately, Sb₂(S,Se)₃ solar cells incorporating IHG-engineered BHJs demonstrate significantly reduced carrier recombination and extended carrier lifetimes (enhancing∼150.5 %), yielding a champion power conversion efficiency of 8.66 % – representing the state-of-the-art for BHJ Sb₂(S,Se)₃ photovoltaics. This IHG paradigm establishes a transformative pathway for fabricating high-performance Sb₂(S,Se)₃ BHJ films and next-generation photovoltaics, redefining quality standards beyond conventional synthesis limitations.