Surface Defect-Compensating Thiophene Ligands Reinforce Charge Transport in CsPbI3 Quantum Dot Solar Cells

All-inorganic CsPbI3 perovskite quantum dots (PQDs) have attracted increasing attention for next-generation photovoltaics owing to their outstanding optoelectronic properties. However, surface defect states─primarily induced by dynamic ligand detachment─severely deteriorate device performance. Herein, a thiophene-assisted solution-phase ligand exchange strategy is developed to fabricate all-inorganic CsPbI3 PQD films with significantly reduced structural defects. The incorporation of 2-Thiophenacetamide (TPT) strengthens interdot electronic coupling, leading to PQD films with improved energetic homogeneity. Density functional theory calculations reveal that TPT exhibits stronger binding energy on PQD surfaces, favoring robust defect compensation and enhanced film stability. Compared with conventionally processed PQD solar cells, the TPT-treated devices demonstrate an increase in power conversion efficiency from 13.7% to 15.1%. This study provides mechanistic insights into the role of thiophene-based ligands in modulating PQD surface chemistry and establishes an effective molecular engineering strategy for achieving high-performance PQD photovoltaics.