Single nanowire OPV properties of a fullerene-capped P3HT dyad investigated using conductive and photoconductive AFM.

The effect of molecular self-assembly on nanoscale photoinduced charge generation of fullerene-capped poly(3-hexylthiophene) (PCB-c-P3HT) films and its effectiveness as a molecular additive in bulk heterojunction P3HT:[6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) is investigated through photoconductive atomic force microscopy. ortho-Dichlorobenzene-cast films of PCB-c-P3HT are found to form interconnected fibrous networks that show high photocurrent generation, while tetrahydrofuran-cast films show nanospheres with relatively low photocurrent generation. The nanofiber size and current generated from these nanowires are shown to vary with additions of PCBM. The PCB-c-P3HT amphiphile is shown to be a successful molecular additive in P3HT:PCBM films. These observations demonstrate how the self-assembly of PCB-c-P3HT into specific nanostructures is crucial to charge generation and transport.