Electrical characterization with high spatial resolution of P3HT:PCBM blends used in organic photovoltaics by means of conductive atomic force microscopy

In the present work, conductive atomic force microscopy is used to obtain high spatial resolution electrical characterization of a donor conjugated polymer, poly(3-hexylthiophene-2,5-diyl) blended with an acceptor fullerene derivative, 95% PC70BM ([6,6]-Phenyl-C71-butyric acid methyl ester) and 5% PC60BM ([6,6]-Phenyl-C61-butyric acid methyl ester), as used in the fabrication of the active layer of bulk heterojunction organic photovoltaic devices. Local spectroscopy scans are performed in dark and light conditions with the objective of analyzing charge carrier transport properties and photocurrent generation. Differences in the electrical properties of semiconducting polymers are evidenced when blending with the acceptor fullerene derivative. Finally, conductive atomic force microscopy is used to provide morphological characterization at the nanoscale using contact scans of biased samples allowing to obtain electrical maps depicting compositional differences.