Efficient bulk heterojunction photovoltaic cells with a pre-organized poly(3-hexylthiophene) phase

This paper presents the controlled generation of nanostructured poly(3-hexylthiophene) (P3HT) from solution to fully fibrillate solid-state films. The fibrillate morphology of P3HT is further maintained when the deposition is carried out from a mixed solution with the acceptor material ([ 6,6]-phenyl-C61-butyric acid methyl ester, PCBM). This enables the fabrication of active layers for bulk heterojunction organic photovoltaic devices with a controlled morphology. The contribution of these nanostructures to the photovoltaic performances is evidenced. High-resolution electrical characterization with conductive atomic force microscopy (C-AFM) confirms an improved charge transport throughout the fibrillate P3HT matrix. A local hole mobility value of 0.9 x 10(-4) cm(2)/V s is derived from the C-AFM measurements. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3628658]