Visible Light Photoconduction of Poly(disilanyleneoligothienylene)s and Doping Effect of C60

The photoconductive properties of poly(disilanyleneoligothienylene)s [PDS(Th) m ; m = 2−4], which have a disilanylene group and an oligothienylene unit in a polymer backbone, and fullerene (C60) doping effects were investigated. It was found that these polymers are photoconductive and have photocarrier generation maxima in accordance with their optical absorption spectra. The polymer PDS(Th)4 was photoconducting when irradiated in the visible light and the quantum efficiency for photocarrier generation was 2% at 480 nm (E = 6 × 105 V cm-1). The hole-drift mobility was measured and ranged between 1.1 × 10-4 cm2 V-1 s-1 at 2 × 105 V cm-1 and 2.1 × 10-4 cm2 V-1 s-1 at 6 × 105 V cm-1 at room temperature. As far as we know, this is the first observation of photocarrier generation in the visible region in silicon-based polymers. Furthermore, C60 doping enhanced the photoconductivity quantum efficiency effectively to 85% at 470 nm (E = 3 × 105 V cm-1) by a photoinduced charge transfer mechanism.