Improved conversion efficiency of AG ₂S quantum dot-sensitized solar cells based on TiO ₂ nanotubes with a ZnO recombination barrier layer

We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO ₂ nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO ₂ nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag ₂S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag ₂S QD-sensitized TiO ₂ nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO ₂ nanotube array and electrolyte.