Photoinduced Charge‐Carrier Dynamics of Phototransistors Based on Perylene Diimide/Reduced Graphene Oxide Core/Shell p–n Junction Nanowires

Abstract

The tailored fabrication of multicomponent nanostructures that can exhibit superior or unique optoelectronic properties compared with those of the single‐component system is highly desirable for fundamental studies of charge transport mechanisms and novel applications with advanced functions. To achieve efficient charge transport and high photoresponsivity, core/shell p–n heterojunction nanowires (NWs) are fabricated using N,N′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide (BPE‐PTCDI) and reduced graphene oxide (rGO) in solution phase. BPE‐PTCDI/rGO core/shell NWs exhibit significantly enhanced photocurrent and faster charge compensation rate under irradiation, compared with pure BPE‐PTCDI NWs. BPE‐PTCDI NW core mainly acts as a light absorption layer, whereas rGO shell functions as a charge transport channel and contributes to a large electrical conductivity. Accordingly, the outstanding light‐detecting performance of BPE‐PTCDI/rGO NWs results from the synergistic combination of the favorable optical and electrical properties of each of the constituent materials. Intriguingly, BPE‐PTCDI/rGO NW organic phototransistors (OPTs) show charge compensation behaviors opposite to those of pure BPE‐PTCDI NW‐OPTs, which is interpreted with a model concerning charge trapping energy levels. The results obtained herein demonstrate great promise for use of carbon‐based multicomponent core/shell nanomaterials in photodetectors, and the developed methodology provides insights into the quantitative analysis of the photogenerated charge‐carrier dynamics of multicomponent semiconducting systems.