Preparation of nano C-ZnO/SnO2 composite photoanode via a two-step solid state reaction with high efficiency for DSSCs

Abstract

ZnO, SnO₂, simple mixed ZnO/SnO₂ (S-ZnO/SnO₂) and complex composite ZnO/SnO₂ (C-ZnO/SnO₂) photoanode films were prepared and applied in DSSCs using a Two-step Solid State Reaction (TSSR) method. The photoanode films were characterized using SEM, XRD and a surface area analyzer, and their optical properties were measured with a UV-vis spectrophotometer. The voltage–current density curve (J–V) and incident photon-to-current conversion efficiency (IPCE) were tested to characterize the performance of the different cells. The results demonstrate that the C-ZnO/SnO₂ photoanode shows a better uniform film structure, larger surface area and dye loading, which causes the device to have a higher power conversion efficiency (PCE) of 5.36% compared to the other three. A lower electron recombination rate and longer electron lifetime are confirmed for the device based on the C-ZnO/SnO₂ photoanode film by analysis with electrochemical impedance spectroscopy (EIS).