Molecular doping of poly(p-phenylenevinylene) under vacuum for photovoltaic application

An insoluble conjugated polymer, poly(p-phenylenevinylene) (PPV) was doped with a dye using the vapor transportation method under vacuum. The used dye was 4-(dicyanomethylene)-2-methyl-6-(4′-dimethylaminostyryl)-4H-pyran (DCM). The concentration of the dye in PPV was evaluated by infrared (IR) spectroscopy as a function of doping conditions, such as temperature and time. The concentration was estimated to be typically 1-20 wt.%. The dye-doped PPV was used for a photovoltaic device, which was a simple Schottky-type device with an aluminum electrode. The device using dye-doped PPV had a photocurrent response at a wavelength longer than that of an undoped PPV device. This suggests sensitizing effect of the dye for collecting light.