A novel hierarchical ZnO-nanosheet-nanorod-structured film for quantum-dot-sensitized solar cells

This study reported the fabrication of hierarchical ZnO NS-NR-structured films by the assembly of ZnO NRs (NRs) on ZnO nanosheets (NSs) by a hydrothermal method . The morphology of the as-prepared ZnO NS-NR films was affected by several factors, such as the TiO 2 intermediate layer, the concentration of Zn(CH 3 COO) 2 in the seed precursor solution, and the hydrothermal reaction time. ZnO NRs were vertically grown on the ZnO NSs under specific conditions. Such ZnO NS-NR films exhibited considerably higher light-scattering ability compared with that of the ZnO NS films. Quantum dot (QD)-sensitized solar cells were assembled using the CdS/CdSe QDs co-sensitized ZnO NS-NR films as the photoanodes. The growth of the ZnO NRs led to the improvement in the short-circuit current density from 12.4 mA cm −2 to 15.1 mA cm −2 . A high power conversion efficiency of 6.0% was obtained with (NH 4 ) 2 TiF 6 treatment for 4 min.