Role of Morphology of Surfactant-Free Nanoparticles in Organic Photovoltaics.

Nanoparticulate (NP) films and organic photovoltaic devices have been fabricated from poly(3-hexylthiophene):phenyl C₆₁ butyric acid methyl ester (P3HT:PC₆₁BM) NP aqueous dispersions prepared by the precipitation method. The NP inks were stable for more than 4 days, and nanoparticle organic photovoltaic (NP-OPV) devices with efficiency (η) of 1% were fabricated. Detailed analysis of the morphology and performance of the precipitated NP-OPV devices indicated that an optimal blend is responsible for the photocurrent and efficiency observed. These results were confirmed by grazing-incidence x-ray diffraction (GIXRD) analysis, which revealed that the precipitated NPs were resistant to thermal phase segregation, allowing thermal conditioning of the NP films. These results show that precipitated NPs provide a pathway to thermally stable NP-OPV devices with higher photocurrents and efficiencies, approaching those of optimal bulk heterojunction (BHJ) OPV devices. [ABSTRACT FROM AUTHOR]