Novel one-dimensional ZnO nanorods synthesized through a two-step post-treatment for efficiency enhancement of dye-sensitized solar cells

Highlights: • Novel 1D irregular ZnO nanorods (IZRH) and ZnO nanoparticles (ZNP) were prepared. • IZRH has a 1D nanostructure with a rough surface and a partially hollow structure. • The introduction of IZRH can significantly enhance the conversion efficiency. • The IZRH/ZNP composite photoanode yielded an overall power conversion efficiency of 7.08%. - Abstract: Novel 1D irregular ZnO nanorods (ZNR) with a rough surface and a partially hollow structure (IZRH) was synthesized through an aqueous chemical growth process, followed by a two-step post-treatment. ZNR was first treated using an innovative hydrothermal method, followed by freezing at subzero temperatures to form IZRH. The as-prepared IZRH was compounded with hierarchical ZnO nanoparticles (ZNP) synthesized through low-temperature solid-phase method. The mixture of IZRH and ZNP was characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; it was used as photoanode in dye-sensitized solar cells (DSSCs). The photovoltaic performance of DSSCs was investigated. Result shows that after freezing post-treatment, IZRH can significantly enhance the conversion efficiency of DSSCs. The maximum power conversion efficiency reaches 7.08%, which is 33% and 45% higher than those of only hydrothermal post-treatment and without post-treatment, respectively