One-step anion-assisted electrodeposition of ZnO nanofibrous networks as photoanodes for dye-sensitized solar cells

Abstract

A highly efficient ZnO photoanode consisting of three-dimensional (3D) nanofibrous-like networks (NFs) for dye-sensitized solar cells (DSSCs) was synthesized using a one-step and seed-layer-free electrodeposition on an indium-tin-oxide (ITO) substrate at 75 °C in a solution containing Zn(NO₃)₂, KCl, NaCH₃COO, and Na₃C₆H₅O₇. In this solution, KCl as the supporting electrolyte promotes the reduction of NO₃⁻ and the diffusion of Zn²⁺, whereas CH₃COO⁻ and C₆H₅O₇³⁻ anions act as the capping agents to selectively inhibit ZnO growth along the c-axis. The photoelectrochemical results reveal that the DSSC based on ZnO NFs has the highest power conversion efficiency (3.78%) in comparison with those of DSSCs based on nanosheets (1.36%), nanorods (2.18%), and microplates (2.55%). This can be attributed to the large dye adsorption amount, efficient light scattering and direct electron transfer networks, which lead to a significant improvement in solar cell performance. Therefore, the ZnO NFs structure can be considered as a promising and efficient photoanode for DSSCs.