Synthesis Of Nano ZnO And Their Application In Polymer Photovoltatic Devices

ZnO is a kind of semiconductor with a broad band gap and excellent high electron mobility, which attracted great attention because of its wide application in the energy industry,medical, manufacturing and so on. Wet chemical reaction method has the advantage of operating easily and synthesizing the samples having complete morphology and high purity,in this paper, we used a variety of preparation methods, such as hydrothermal method, sol-gel method and solution growth method, to synthesize nano zinc oxide, and used the chemical bath deposition and SILAR method to coat surface of the ZnO nanoarrays.The main research was:（1）Hydrothermal growth of nanoparticlesA hydrothermal method has been adopted to synthesize ZnO samples by using zinc nitrate, zinc acetate and zinc sulfate as precursors. Different nanostructures are obtained, such as nanoflowers, nanoflakes and nanoprisms. The three samples are hexagonal wurtzite structure. The different counterions show an important influence on the morphology, crystal quality and optical properties of synthetic ZnO samples. The results show ZnO samples from zinc nitrate with larger particle sizes possess fewer oxygen vacancies and defects, while acetate sample with smaller particle sizes has more oxygen vacancies and defects. It was speculated that acid radical ion influences the morphology, caused the different aggregation growth. The Raman spectrum of three kinds of sample, in addition to crystalline nitrates get samples, other samples only intrinsic peak of the 435 cm- 1 is measured. The conclusion was that in three kinds of system the sample synthesized by nitrate salt had a better crystallization performance.（2）Controllable growth of ZnO nanoparticle arraysIn order to be applied well in organic solar cells, the sol gel method and solution growth method were combined to grow ZnO nanorods on ITO substrates, because the nanorods are more advantageous to the electronic vertical transmission.First attempt to grow in the ITO glass plate nanorods, Without the seed layer, it is hard to grow the vertical nanorods. Whenhaving a seed layer on ITO glass, the growth has the priority to grow on the seeds.When using TiCl₄ pretreated on the surface of the ITO, the attachment of seed layer and surface of ITO is improved, and the roughness on the surface of the ITO is increased,resulting that rod density can be control by appropriate pretreatment.The concentration of the precursor solution of seed layer and the number of spin-coating can also control the density.The results show that by controlling the concentration of TiCl4 solution, the concentration of the precursor solution,and seed number of spin-coating can determin the density of ZnO nanoparticle arrays.（3）The preparation and performance of coated ZnO nanorodsThere are a great many defects on ZnO nanorods surface, which can cause the electrons and holes in the compound, and increases the probability of quenching. In this paper, we try to coat the surface of nanorods, which can expand absorption area as well, for the improvement of the efficiency of organic solar cells.CdSe nanoparticles coat ZnO nanoarays by chemical deposition method and silar method respectively. Through a series of tests, CdSe successfully coat on nanorods, Sb₂S₃ particles coat on the nanorods by silar method, because the solution is corrosive, resulting the corrosion of（002） crystal plane of nanorods and the formation of nanotubes.Bi₂S₃ wrapped on the surface of nanoarrays by silar method, and the mapping results also confirm the successful coating. Cu2 S is deposited on the surface by silar method,when the silar circle times are three, Cu2 S has become a membrane on the nanorods.After four different material wrapped with nanometer ZnO, All had impact on the absorption of ZnO with broadening the absorption band.We ues ZnO nanoarray and ZnO/coatig material to fabricate the photovoltaic devices, and the J-V lines show that the coated ZnO nanoarray have higher Jsc.Indeed, the PCE valves have been improved.