Optimized Design And Experimental Study Of The Optoelectronic Properties Of Nano-composite Structures

Environmental pollution and depletion of natural resources have become the mostserious global problem in the21st century, which threat human survival. Photoelectricconversion can convert solar energy into electric power or enhance photocatalysis, etc.,as we need, which can alleviate the current energy crisis. The research onsemiconductor materials and structures that can improve the conversion efficiency ofphotovoltaic and photocatalysis devices has great practical significance. Nowadays,nanometer semiconductor materials and their composite structures can be fabricatedmaturely and they are extensively used in the field of photoelectric conversion, while athin film of metal nanoparticles, having a near-field enhancement effect of thesemiconductor structure, is very efficient in improving the photoelectric conversionefficiency.In this paper, by the combining numerical simulation with experiments, wechoose some metal/semiconductor nano-composite structures and optimize the designto achieve high photoelectric conversion efficiency by considering the localizedsurface plasmon resonance (LSPR) effects in these structures. Following this scheme,structures such as ZnO/Cu2O, TiO2/Ag/TiO2, and CdS/CdTe are chosen, and Aunano-film combing with semiconductor nano-materials have also been optimized byemploying finite difference time domain (FDTD) simulation method. The opticalproperties of as-designed composite nanostructures are analyzed for the as-optimizedstructure, AFORS-HET software is used to explore the solar cell performance ofCdS/CdTe semiconductor nanostructures, and optimized parameters are shown toguide the following experimental researches.ZnO nanowire films are prepared by electrochemical method, Au nano-films areand Cu2O nano-films are both prepared by the vacuum magnetron sputtering,ZnO/Cu2O and ZnO/Au/Cu2O nanocomposite structures are grown by combination ofthese methods. In these experiments, isolated Au nanoparticles are achieved by thermalannealing processes. Optical absorption and photocatalysis performances ofas-prepared composite nano-structures are studied, and the impacts of Au decoration tothe photoelectric conversion efficiency are also discussed.TiO2/Ag/TiO2nano-composite structures are grown by magnetron sputteringmethod. By studying their optical absorption and photo-electrical properties, the impacts of Ag decoration on the photoelectric conversion efficiency are also discussed.Finally, CdS nano-films are grown by the chemical bath deposition method, CdTenano-films are grown by the magnetron sputtering system, and CdS/CdTe solarcellprototype devices are fabricated. The effects of nano-Au film on the CdS/CdTe solarcell performance are discussed.The results in this thesis show that: the near-field field enhancement effect ofsurface plasmon resonance occurs in the metal thin film decorated in nano-compositessemiconductor structures, which can promote the performance of photoelectricconversion. Our present researches will guide the design of nano-compositessemiconductor structures with high photoelectric conversion efficiency.