Determining the structural motif of P3HT:PCBM nanoparticulate organic photovoltaic devices

Poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends are the most studied organic photovoltaic materials system and conventionally are processed into thin films via organic solvent based routes. Recently, the fabrication of OPV devices from water-dispersed nanoparticulate materials (solar paint) has attracted increasing interest since it offers the potential of morphological control coupled with device processing in the absence of an organic solvent. However, to date the reported efficiencies of nanoparticulate organic photovoltaic (NP-OPV) devices have been disappointingly low, reflecting a lack of understanding of the structural motif. In this letter, we probe directly the structural motif of P3HT:PCBM NP-OPV devices and show how NP morphology determines device function.