Application of ZnO micro-flowers as scattering layer for ZnO-based dye-sensitized solar cells with enhanced conversion efficiency

• ZnO micro-flowers were synthesized by a simple solution deposition method.
• ZnO micro-flowers were used as scattering layer for dye-sensitized ZnO solar cells.
• ZnO micro-flowers/nanoparticles bilayer solar cell has much higher conversion efficiency due to scattering effect.

ZnO micro-flowers were synthesized by a simple solution deposition method without the need of seed or keeping fresh deposition solution. The synthesized ZnO micro-flowers were used as scattering layer for dye-sensitized solar cells (DSSCs) fabricated with ZnO nanoparticles photoanode. The UV–vis diffused reflectance absorption spectra (DRS), electrochemical impedance spectroscopy (EIS) and photoinduced open-circuit voltage decay (OCVD) measurements show that the ZnO micro-flowers/nanoparticles bilayer film-based solar cell has much higher light harvesting efficiency, lower resistance and longer electron lifetimes as compared with the ZnO nanoparticles film-based one, and consequently resulting in an improved conversion efficiency due to the scattering effect of ZnO micro-flowers layer. The simple methods of the fabrication of both the ZnO micro-flowers and the ZnO bilayer film-based solar cell, which was fabricated with photoanode consisting of ZnO nanoparticles as underlayer and ZnO micro-flowers as overlayer, are promising for the development of the low-cost, eco-friendly, and durable devices with high light-to-electricity conversion efficiency.