Preparation Of CdS And CdSe Sensitized ZnO Nanorod Array Films And Their Photoelectrochemical Properties

Human's lifes mainly depend on coal,oil and natural gas,but these fossil fuels will be depleted someday in the future because they are limited.Moreover,carbon dioxide is produced in the combustion of fossil fuels and the rapid increase of carbon dioxide concentration has affected the climate,resulting in the global warming effect.Under these circumstances,photovoltaic(PV)solar cell as an alternative and clean energy source has attracted great attention.The sensitized solar cells have been an active research project since 1991 because of their simple preparation process,low cost and stable performance.Lots of trials have been made in order to enhance their solar energy conversion efficiency.One of the most important approaches is to tuning the absorption spectra of the sensitizer.Nowadays,the dye-sensitized solar cells(DSSCs)which are based on organic dye have achieved the highest efficiency among all of the sensitized solar cells.But the dye is too expensive and not very stable,these drawbacks limit its utilization on solar cell.The special size-selected optical property of the inorganic semiconductor nanocrystals makes it easy to tune the absorption spectrum of inorganic semiconductor particles.In addition,these nanocrystals are easier to fabricate.Thus,inorganic semiconductors can be alternative candidates to fabricate solar cells.In this thesis,ZnO nanorod arrays electrodes sensitized by CdS and CdSe were successfully prepared,respectively. Moreover,we also systemically investigated their photoelectrochemisty properties.Firstly,the ZnO nanorod arrays were grown on the ZnO nanoparticles-coated TCO glass by using the hydrothermal method.ZnO@CdS core-shell nanorods array film electrode was fabricated after CdS being deposited through chemical bath deposition method.The photoelectrochemical property of this new electrode was also measured in the solar cells.The ZnO@CdS core-shell nanorods array film electrode displayed superior performance than that of both electrodes composed of only ZnO nanorods array film and CdS nanocrystalline film.We also investigated the influence of different deposition time and the morphology of ZnO substrate on the cell performance.It showed that the one-dimension ZnO nanorod arrays film and appropriate deposition time of CdS played an important role on the improvement of cell electrochemical performance.Secondly,ZnO@CdSe core-shell nanorods array films were synthesized by a two-step method,in which ZnO nanorods array films were first grown on TCO substrate,and CdSe nanocrystals were then deposited on these nanorods to form core-shell structured films.We measured the photoelectrochemical performance of the resulting ZnO@CdSe core-shell nanorods array films as the solar cell photoanodes.The parameters such as the length of ZnO nanorods,the phase structure and the deposition time of CdSe were found to greatly affect the photoelectrochemical performance of the solar cell.