Zinc Oxide, Metal Sulfide Nanocrystals:Synthesis And Application In Solar Cells

Energy and environment have become the focus of the development for humansociety since21centrary. The progress and application of clean and low carbonicenergy are extremely urgent, and the research of solar cells with high efficiency and lowprice is one of the most important works. Zinc oxide and metal sulfidenanomaterials are widely used in fabrication of solar cells. It’s very important ofassembly functional structure of solar cells and optimizing the energyconversion efficiency by tuning sizes and morphology of nanomaterials in liquidsynthetic systems. This dissertation focuses on the solution-based syntheticroutes for zinc oxide and metal sulfide nanostructures, as well as therelationship between structures of zinc oxide films of different sensitizedmethods and the energy conversion efficiency of solar cells.Based on the solvothermal synthetic strategy, a facile method has been establishedto synthesize zinc oxide hierarchical aggregates. The sizes and morphology of theaggregates can be tuned by the proportion of zinc salt and alkali in proper tempreture.These aggregates assembled with nanocrystallites of5nm through oriented attachmentand3-D assembling are unique mesopous materials with high BET surface. Differentsizes of nanoparticles are obtained in solvothermal hydrolysis reaction of zinc acetatedehydrate.1-D nanostructure can be formed by adding some alkali in the reaction, whilehomogenous growth happens by adding acid. Besides, zinc oxide hierarchical nanorodsare synthesized by controlling the concentrations of zinc acetate andhexamethylenetetramine in aqueous solution.An optimized fabrication method for zinc oxide photoanode has been developed bychoosing from different method for pastes with zinc oxide nanomaterials to keep themesopous structures of the aggregates. Comparing with photoanode assembled withzinc oxide of nanoparticls and nanorods, dye sensitized solar cells (DSCs) with zincoxide aggregates show higher light to energy conversion efficiency. Among theaggregates of different sizes and morphology, quasi-spheric aggregates of sizesmatching with wavelength of visible lights get the highest performance in DSCs.Investiagtion of relationship between performance of qutuam dots sensitized solar cells (QDSCs) and different photoanode structure with various qutuam dots are carried outby using two sensitized methods of qutuam dots followed with I-V testing of QDSCs.A facile synthetic method has been introduced to prepare metal sulfidenanocrytsals in dodecanol. Nanocrystals of single metal sufide such as PbS, alloyedsufide and heterostructure are prepared with reaction of metal oleic acid complex ormetal oleyamine complex and powdered sulfer. The reaction system is mild and easilycontrolled for tuning the sizes and morphology of nanosturctures, and is suitable forscale preparation of metal sulfide nanocrystals.