Fluorescence and sensitization performance of phenylene-vinylene-substituted polythiophene

A new kind of polythiophene derivative, Poly（3-{2-[4-（2-ethylhexyloxy）-phenyl]-vinyl}-2,2＇-bithiophene） （PTh）, was applied in dye-sensitized solar cell to extend the light response of nanocrystalline TiO2 electrode. UV-vis absorption and fluorescence spectra were employed to investigate the interaction of PTh with nanocrystalline TiO2. The absorption coefficient of the PTh was high in visible part of spectrum, and the fluorescence emission of the PTh can be efficiently quenched by TiO2 nanoparticles owing to charge injection from the excited singlet state of PTh to the conduction band of the TiO2 particles. Cyclic voltammetry measurements were performed to study the dye regeneration reaction at the na- nocrystalline TiO2/electrolyte interface. The solar cell sensitized with PTh exhibited a short-circuit photocurrent （Isc） of 3.08 mA/cm^2, an open circuit voltage （Voc） of 511 mV and an overall efficiency of 0.9% under the illumination of 100 mW/cm^2 （AM 1.5）.