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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 nanocrystalline TiO2/electrolyte interface. The solar cell sensitized with PTh exhibited a short-circuit photocurrent (I sc) of 3.08 mA/cm2, an open circuit voltage (V oc) of 511 mV and an overall efficiency of 0.9% under the illumination of 100 mW/cm2 (AM 1.5).

The nanocrystalline TiO 2 electrode of polythiophene sensitized solar cell was modified by coating gold nanoparticles with thermal decomposition method. The surface concentration of polythiophene adsorbed on TiO 2 electrode was increased obviously due to the participation of gold nanoparticles. The interfacial charge transfer kinetics were investigated by analyzing of photocurrent action spectrum of polythiophene sensitized TiO 2 electrode and fluorescence spectrum of polythiophene solution in the presence of TiO 2 nanocrystals. After modification with Au nanoparticles, short circuit current of polythiophene sensitized solar cell increased from 2.68 mA cm −2 to 3.92 mA cm −2 and power conversion efficiency from 0.88% to 1.30% at AM 1.5.

The electrophoretic deposition combined with common pressure hydrothermal treatment was employed to prepare nanocrystalline TiO2 thin film from suspension of tetra-n-butyl titanate and P25 at low temperature. The tetra-n-butyl titanate was hydrolyzed and crystallized into anatase to interconnect nanocrystalline TiO2 particles and to stick them to a conductive substrate by common pressure hydrothermal treatment to improve the electron transport properties of the deposited thin film. A dye-sensitized solar cell based on TiO2 thin film prepared by the low temperature method yielded the conversion efficiency of 6.12%. Due to the relative slower electron transport rate in the deposited film, its conversion efficiency was slightly lower than that of the cell with TiO2 thin film prepared by the conventional high temperature sintering method. Since it is free of high temperature sintering step, this method can be used to prepare nanocrystalline TiO2 thin film on plastic polymer conductive substrate for fabrication of flexible dye-sensitized solar cell.

A new method for preparing platinum-modified electrodes by attracting nanometer-sized platinum particles from hydrosol to –SH coated surface of conductive glass obtained through Langmuir technique has been proposed. The electrode possessed a surface modified with homogeneously distributed platinum nanoclusters and a low platinum loading. The catalytic activity of thus fabricated electrode for the triiodide reduction was investigated by electrochemical impedance measurements. The charge-transfer resistance at the interface of electrolyte/electrode was much lower and the corresponding exchange current density was several hundreds micro ampere per centimeter square larger than conventional thermal decomposed Pt-modified electrode and Pt foil electrode.