Achieving over 10 % Efficiency in Poly(3‐hexylthiophene)‐Based Organic Solar Cells via Solid Additives

Abstract The photovoltaic performance of organic solar cells (OSCs) based on poly(3‐hexylthiophene) (P3HT) has been steadily improved by developing novel non‐fullerene acceptors (NFAs) in recent years. Herein, to further improve the performance of P3HT‐based OSCs, a solid additive (SA4) and a typical solvent additive [1,8‐diiodooctane (DIO)] were employed to process P3HT:ZY‐4Cl‐based OSCs, respectively. In comparison with the DIO‐processed device, the SA4‐processed one exhibited a more ordered molecular packing and more favorable phase separation, leading to enhanced charge transport and reduced carrier recombination. As a result, the SA4‐processed device delivered a power conversion efficiency (PCE) of 10.24 %, which was much higher than that of the DIO‐processed counterpart (6.26 %). This work reported a PCE over 10 % in P3HT‐based OSCs for the first time, indicating the promising development of P3HT‐based OSCs by morphological modulation.