Tailoring Iodide-Capturing Molecules for High-Performance Perovskite Solar Cells Based on P3HT

Poly(3-hexylthiophene) (P3HT) has attracted significant interest due to its cost-effective synthesis, high purity, and stable film properties. However, the efficiency of perovskite solar cells is limited by energy-level mismatches and nonradiative recombination at the P3HT/perovskite interface. In this study, we introduce the 2,7-dimetapyridinebenzo[4,5]thieno[3,2-b]benzofuran (Mpy-BTBF) small molecule, which features extended π -conjugation and lone pair electrons from oxygen and sulfur atoms. Incorporating Mpy-BTBF into P3HT (M-P3HT) improves charge transport and passivates iodine-related defects, achieving a power conversion efficiency (PCE) of 16.36%, surpassing the pristine P3HT-based device (14.49%). With further Li salts doping, the champion PCE increased to 21.24 from 17.30%. Finally, M-P3HT-based devices maintained over 70% of their efficiency after 600 h of aging at 60% relative humidity and 60°C.