Novel Zn–Sn–O nanocactus with excellent transport properties as photoanode material for high performance dye-sensitized solar cells

Abstract

A novel chemically stable Zn–Sn–O nanocactus structure has been synthesized for the first time using a hydrothermal method. The Zn–Sn–O nanocactus structure comprises a Zn poor-Zn₂SnO₄ plate and Zn-doped SnO₂ nanothorns growing on the plate, both of which have high electron mobilities. The nanocactus is used as the photoanode of dye-sensitized solar cells (DSSCs). The overall power conversion efficiency (PCE) for the Zn–Sn–O nanocactus film reaches 2.21%, which is twice the previous reported efficiency of pure SnO₂. Electrochemical impedance spectroscopy (EIS) measurements show that the Zn–Sn–O nanocactus film has a good effective diffusion length and high intrinsic electron mobility. After TiCl₄ treatment of the Zn–Sn–O nanocactus film, the current density increases nearly three times and the PCE increases to 6.62%, which compares favourably with the P25 DSSCs (6.97%) and is much higher than that of the SnO₂ (1.04%) or Zn₂SnO₄ (3.7%)-based DSSCs.