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.