TiO2 nanoparticles was introduced into quasi-solid-state Poly(vinylidenefluoride-co-hexafluoropropylene) (P(VDF-HFP)) based gel electrolyte to form nanocomposite gel electrolyte for quasi-solid-state dye-sensitized solar cells. The steady-state voltammograms revealed that the diffusion performance of the triiodide and iodide in the quasi-solid-state P(VDF-HFP) based gel electrolyte was greatly enhanced after the addition of TiO2 nanoparticles. Especially, the apparent diffusion coefficient of 13 increased from 0.76 x 10(-10) m(2)/s to 4.42 x 10(-10) m(2)/s, reached the level of the liquid electrolyte (4.04 x 10(-10) m(2)/s). By introducing TiO2 nanoparticles, the photoelectric conversion efficiency of the gel based device increased from 5.72% to 7.18%, which reached the level of the liquid electrolytes based device (7.01%). The electrical impedance spectrum revealed that the addition of TiO2 nanoparticles could reduce the charge recombination at the interface of dyed TiO2 electrode/electrolyte. The results of the accelerated aging tests showed that the nano-TiO2 composite gel electrolytes based devices could maintain 90% of their initial value after heating at 60 degrees C for 1000 h, which indicated that they had better thermostability than the corresponding normal gel electrolyte based devices and liquid electrolyte based devices. (c) 2007 Elsevier B.V. All rights reserved.