One-Step, Surfactant-Free Hydrothermal Method for Syntheses of Mesoporous TiO2Nanoparticle Aggregates and Their Applications in High Efficiency Dye-Sensitized Solar Cells

Abstract

A facile, one-step, template-less, surfactant-free hydrothermal process, using a metal salt as the precursor, is developed to prepare submicrometer sized mesoporous TiO2 nanoparticle aggregates (NPGs). The as-prepared TiO2 NPGs are crystalline of the anatase phase, with a high specific surface area of 166 m2/g, an average pore size of 8.9 nm, and an average NPG size of 840 nm. With these NPGs, a new form of composite photoanode, consisting of the mesoporous TiO2 NPGs and xerogels, is proposed for high efficiency dye-sensitized solar cells (DSSCs). TiO2 xerogels are incorporated into the TiO2 NPGs layer with an impregnation process to form the TiO2 NPGs/xerogels composite. A high power conversion efficiency of 8.41% is achieved for DSSCs based on the TiO2 NPGs/xerogels composite photoanode, representing a 38% efficiency boost over the efficiency of 6.11% achieved with a P25 TiO2 based cell. The success of the present composite TiO2 nanostructure can be attributed to the effective utilization of the inter-N...