Thickness-Insensitive Organic Solar Cells with 19.61% Efficiency Processed from All-Hydrocarbon Solvent and Solid Additive

Abstract

Organic solar cells (OSCs) have achieved power conversion efficiencies (PCEs) of >20%, although almost all top-performance devices having a thin active layer of ≈100 nm and are being processed with environmentally harmful halogenated solvents/additives. However, attempting to fabricate OSCs with thick active layers from non-halogenated solvents/additives normally leads to dramatically decreased PCEs, seriously restricting their industrialization. To overcome the above shortcomings, it is developed an all-hydrocarbon-based system combined with toluene solvent and fluorene (DBP) solid additive to process active layer (PM6:L8-BO) thickness-insensitive efficient OSCs. Owing to DBP having good planarity, excellent volatility, and stronger interaction with L8-BO, its treated active layers exhibit ordered molecular packing, suitable phase separation, and enhanced charge transport, resulting in a superior PCE of 18.64%. Notably, using D18:BTP-eC9 as the active layer, the OSCs achieve a record-high PCE of 19.61% among the all-hydrocarbon-based system processed devices. Due to the increased crystallinity and optimized hierarchical morphology, the above OSCs show high thickness-tolerance and provide an excellent PCE of ≈18% with a 300 nm active layer, ranking among the highest PCEs for the all-hydrocarbon-based system processed thick-film devices. This work develop an all-hydrocarbon-based system to process active layers in an environmentally friendly way for thickness-insensitive OSCs, with record-high PCEs, toward future industrial production.