The mediated aggregation behavior of buried donor via 2-chlorothiophene solvent in the layer-by-layer organic photovoltaic for indoor application

The proliferation of Internet of Things ecosystems necessitates high-performance indoor organic photovoltaics with hierarchical morphology microsctructure and suppressed trap-mediated recombination. Herein, we employ a layer-by-layer (LBL) solution processing approach integrated with solvent-directed crystallization kinetics to govern the donor polymer assembly. Notably, in comparison with chlorobenzene (CB), 2-chlorothiophene (2Cl-Th) can shorten the liquid-to-solid transition window, which can inhibit the over-aggregation of D18 polymer. This retarded aggregation is beneficial for the acceptor infiltration into the buried D18 layer to form more donor–acceptor interfaces, which can facilitate the exciton splitting dynamics. More critically, this kinetically optimized morphology can reduce the trap-state density by 10.8% and prolongs charge carrier lifetime by 44.5%. Indeed, the optimized 2Cl-Th-processed D18/L8-BO LBL devices deliver the performance of 27.6% under 3000 K light emitting diode (LED) illumination (1500 lux), where the CB casted devices yielded a moderate performance value of 23.7%. More crucially, the 2Cl-Th solvent strategy possesses a universality, where D18/ITIC-Th systems can also harvest a performance of 25.7%.