The Synthesis of Nb-doped TiO2 Nanoparticles for Improved-Performance Dye Sensitized Solar Cells

Abstract

The current co-hydrolysis used for the preparation of Nb-doped TiO2 starts from expensive and unstable niobium-based precursors, which is not suitable for mass production. In this paper, a scalable synthesis of Nb-doped TiO2 nanoparticles (NPs) made by mixing TiO2 paste with functionalized Nb2O5 sol gel is developed for the photoanodes in dye-sensitized solar cells (DSSCs). By doping Nb into TiO2, the positive shift of conduction band minimum (CBM) enhances the electron injection and the improved electron conductivity facilitates the electron transport, leading to an improved Jsc. In addition, the Nb-doping suppresses the surface recombination at TiO2-electrolyte interface, resulting in the increase of Voc. Therefore, the DSSCs based on 2.0 mol% Nb-doped TiO2 photoanodes improve both Jsc and Voc to achieve 18.9% improvement of photoconversion efficiency as compared with the standard DSSCs. The DSSCs with Nb-doped TiO2 photoanode is also shown an improved long-term stability.