A simple route for decorating TiO2 nanoparticle over ZnO aggregates dye-sensitized solar cell

The development of a simple and reproducible route to modify ZnO surface with TiO2 is urgent for harnessing multiple interfaces and enhancing performance of ZnO dye-sensitized solar cell (DSSC). Here, we reported a simple method to decorate TiO2 nanoparticles for ZnO DSSC. By simple immersing ZnO film into butyl alcohol solution of tetrabutyl titanate (TBOT), TiO2 nanoparticles were well decorated onto ZnO nanocrystal surface. By taking the advantage of the hydrolysis and condensation differential of different TiO2 precursors, the simple method allows an easy tune over the TiO2 modification structure on ZnO surface for DSSC application. The influence of ZnO/TiO2 modification structure on the photoelectron collection mechanism of DSSC was discussed. The DSSC with ZnO/TiO2 nanoparticle has better photoelectron collection mechanism comparing with that of ZnO/TiO2 layer modified by titanium isopropoxide (TTIP) solution, leading to larger photocurrent and better DSSC performance. The DSSC performance of ZnO/TiO2 nanoparticle declines as the concentration of TBOT greater than 0.50 M, which is mainly caused by the electron collection mechanism change originating from ZnO/TiO2 modification structure.