Highly efficient Quasi-Solid-State Dye-Sensitized Solar Cells Based on Electrospun TiO2 Nanorod
Enhancement in device efficiency of dye sensitized solar cells (DSSC) has been continuously reported by many researchers. Most of high performance devices were fabricated using TiO2 nanoparticles with a diameter of a few tenths of nanometer and liquid electrolytes systems. However, the conventional TiO2 nanoparticle based DSSCs with polymer gel electrolytes showed much lowers device efficiency. Besides slower charge transfer in high viscosity polymer gel, small pore size of TiO2 nanoparticles film hinders complete penetration of gel electrolyte resulting in the lower device efficiency. Network of TiO2 nanorods is certainly an attracting structure for DSSCs in terms of high surface area and porosity. In this work, quasi-solid-state dye sensitized solar cells (DSSC) were demonstrated using TiO2 nanorods and a polymer gel electrolyte. Networks of TiO2 nanorods were obtained using electrospinning technique. Electrospinning is a remarkably simple method to generate one-dimensional (1D) nanostructures of polymers and metal oxides. The TiO2 nanorods were 60 - 100 nm long with a diameter of ~ 15 nm, and the network has approximately two times larger surface area compared to the same weight of conventional nanoparticles (diameter ~ 25 nm). Furthermore, the highly porous nature of the networks helps the viscous polymer gel electrolyte to penetrate efficiently. As a result, the electrospun nanorod based DSSC showed improved efficiency of approximately 20% compared to the conventional TiO2 nanoparticle based quasi-solid state DSSCs.