Long‐Range Ordered Organic Bulk‐Heterojunction: C60 and O‐IDTBR Single Crystals Penetrated by Crystalline P3HT Fibrous Networks

Abstract

AbstractThe long‐range ordering of bulk‐heterojunctions (BHJs) significantly facilitates exciton diffusion and dissociation as well as charge transport. A feasible bio‐inspired strategy to realize such a heterostructure is crystallization in gel media where the growing host crystals incorporate the surrounding guest materials of gel networks. Until now, the host–guest pairs forming ordered BHJs are still very limited and, more importantly, the used gel‐network guests are structurally amorphous, spurring investigation toward crystalline gel‐networks. Here, single crystals of fullerene and non‐fullerene acceptors (NFAs) in poly(3‐hexylthiophene) (P3HT) organogel are prepared, forming C60:P3HT and (5Z,5″Z)‐5,5″‐((7,7″‐(4,4,9,9‐tetraoctyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b″]dithiophene‐2,7‐diyl)bis(benzo[c][1,2,5]thiadiazole‐7,4‐diyl))bis(methanylylidene))bis(3‐ethyl‐2‐thioxothiazolidin‐4‐one) (O‐IDTBR):P3HT BHJs. The crystalline P3HT network penetrates the crystal matrix without significantly disturbing the single crystallinity, resulting in long‐range ordered BHJs. This bi‐continuous structure, together with an improved overall ordering, contributes to enhanced charge/energy transfer. As a result, photodetectors based on these ordered BHJs exhibit ameliorated responsivity, detectivity, bandwidth, and stability as compared to the conventional BHJs with short‐range ordering. Therefore, this work further extends the scope of long‐range ordered BHJs toward crystalline polymer donors and NFAs, providing a generally applicable strategy for the design of organic optoelectronic devices with superior performance.