Facile fabrication of an organic semiconductor/graphene microribbon heterojunction by self-assembly

Herein, we report a facile self-assembly strategy to prepare a novel 1D organic semiconductor/graphene microribbon heterojunction by coating a layer of graphene sheets on the organic semiconductor microribbon. The organic semiconductor microribbon composed of a p-type small molecule 3,7-bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[2,3-b:2′,3′-e]pyrazine (BEHT-DTP) was prepared by evaporation-induced self-assembly. Subsequently the graphene nanosheets, as an electron acceptor, were self-assembled onto the surface of a BEHT-DTP microribbon in aqueous solution to form a 1D p–n junction. The device based on the single microribbon heterojunction demonstrated enhanced photoconductivity properties. This preliminary work points out a new path to fabricate 1D organic nano/micro-heterojunctions, avoiding complex molecular design and equipment.