The effect of dispersion of TiO2 nanoparticles on preparation of flexible dye-sensitized photoanodes

Generally, nanoparticles are easy to aggregate due to their nano sizes, which influence the physical and chemical properties. In this work, a dispersion treatment of the TiO2 nanoparticles with different average sizes was employed to improve the dispersion of TiO2 nanoparticles, in order to prepare flexible photoanodes for dye-sensitized solar cells (DSCs) with novel photovoltaic properties at a low temperature. The effects of dispersion treatment on the dispersion of TiO2 nanoparticles, including the viscosities of the binder-free TiO2 paste, the morphologies and textural properties of nanoparticle-TiO2 films, and the photovoltaic properties of the flexible DSCs, were investigated. Flexible indium-tin oxide (ITO)-coated polyethylene naphthalate (PEN) substrates with sputter deposited Pt were employed as the transparent flexible counter electrodes. A short-circuit photocurrent density of 9.62 mA·cm−2, an open-circuit voltage of 0.757 V, a fill factor of 0.589 and an overall light-to-energy conversion efficiency of 4.29% for the flexible DSCs under AM1.5 illumination of 100 mW·cm−2 were obtained with dispersion treatment. A 30.8% increment of the energy conversion efficiency for DSCs made by dispersion treatment was obtained compared with that made without dispersion treatment.