Combined photoanodes of TiO2 nanoparticles and {001}-faceted TiO2 nanosheets for quantum dot-sensitized solar cells

Abstract

A key point for constructing quantum dot-sensitized solar cells (QDSSCs) with high efficiency is to improve the utilization of sunlight. While various TiO₂ morphologies such as nanoparticles, nanosheets, nanotubes and nanorods have been used as photoanodes of QDSSCs for improving cell performance, these investigations are generally focused on a single morphology of TiO₂. Herein, a combined photoanode structure based on TiO₂ nanoparticles and {001}-faceted TiO₂ nanosheets have been designed, which exhibits improvement in cell performance. Owing to the strong light scattering and fast electron transfer ability of TiO₂ nanosheets, an optimal power conversion efficiency of 4.98% with a short circuit current density (J_sc) of 17.57 mA cm⁻², an open circuit voltage (V_oc) of 0.63 V and a fill factor (FF) of 0.45 is achieved compared to the TiO₂ nanoparticle photoanode (3.61%). The present work offers a feasible method towards improving the efficiency of QDSSCs.