CdS/ZnO Heterostructure: Fabrication And Photoelectrochemical Properties

With the rapid development of modern industry process, the energy requirement of people is further rising. Solar energy, as one of the most important renewable energy sources, has attracted considerable attentions. Exploiting solar energy at a low cost has been a big challenge for the human society. In order to convert and utilize solar energy more efficiently, searching a thin narrow band-gap semiconductor heterojunction solar cell with stable performance and high photoelectric conversion efficiency, we fabricated the CdS/ZnO heterojunction and analyzed its photoelectrochemical properties.The main content of this study is listed as follows: On one hand, we have synthesized ZnO nanowire array successfully, controlling the morphology of nanowire such as length, density, aspect ratio, orientation etc by changing the conditions of nucleation and growth. On the other hand, ZnO nanowire array was conformally coated with an ultrathin CdS shell layer and then the narrow band-gap semiconductor thin layer/oxide semiconductor nanowire electrode with favorable light absorption property has been prepared successfully by regulating the light absorption layer thickness.The structure and the optical properties of ZnO nanowire and CdS/ZnO nanowire heterojunction are investigated by XRD,SEM, TEM, Raman, and UV-visible absorption spectra.We have studied the effects of deposition conditions, annealing heat treatment etc on the uniformity, thickness, and grain size of CdS thin layer. Furthermore, we have studied the effect of thickness and grain size of CdS layer on the photosensitizing efficiency of ZnO nanowire by means of photoelectrochemistry. Optimal CdS/ZnO nanowire heterojunction (depositing CdS 50 times on 2 microns-length ZnO nanowire array) was achieved and applied to I/I3- electrolyte system eventually. The cell photoelectric conversion efficiency was 0.51%.