Suppressing Morphological and Energetic Disorder in Copper Antimony Sulfide-based Hole-Transporting Materials via Ligand-Precursor Engineering for Efficient and Stable Perovskite Solar Cells.

Dopant-free inorganic hole-transport layers (HTLs) are promising for improving the efficiency and stability of perovskite solar cells (PSCs). Here, CuSbS2 nanocrystals are engineered through sulfur-precursor and ligand-coordination chemistry using hexamethyldisilathiane (TMS) and thiourea (ThU) combined with oleylamine/oleic acid (OAm/OAc) ligands. While the TMS route reduces platelet dimensions, the ThU precursor with an optimized OAm: OAc ratio of 3:7 suppresses excessive anisotropic growth and induces mixed plate-like/quasi-spherical nanostructures, leading to denser particle packing and improved interfacial coverage. Structural and electronic analyses reveal that sulfur-release kinetics and ligand coordination govern morphology evolution, energetic disorder, and interfacial charge-transfer behavior. As a result, PSCs employing ThU-derived CuSbS2 HTLs achieve a champion power conversion efficiency of 22.72% with 0.82 for fill factor, outperforming TMS-derived (20.00%) and ES-derived (17.31%) counterparts. The optimized devices also exhibit enhanced operational stability under illumination and thermal aging conditions. These findings establish sulfur-precursor and ligand engineering as an effective strategy for high-performance inorganic HTLs in PSCs.