| Hybrid organic-inorganic lead halide perovskites have attracted stunning attention due to their potential applications in a wide variety of high-performance optoelectronic devices.Especially in recent years,photovoltaic cell energy conversion efficiency of hybrid organicinorganic lead halide perovskite has been more than 20%,which benefits from its excellent properties: high carrier mobility,long diffusion length and high extinction coefficient.The nanocrystalline geometry and size are closely related to the physical properties,and the changes in morphology at nanoscale bring different optical and electronic properties.The acquisition of nanoscale perovskite materials will greatly enrich the application of this material.At the same time,hybrid organic-inorganic lead halide perovskite can be easily destroyed due to its low formation energy.Stability has become a bottleneck restricting the development of perovskite devices.In this dissertation,Synthesis and photoelectric properties of hybrid organic-inorganic lead halide perovskite nanomaterials have been studied.Stable perovskite composites have been obtained.Our study provides a valuable theoretical and experimental evidence for the further development of hybrid organic-inorganic lead halide perovskites synthesis theories and optoelectronic applications.The main results in this dissertation can be summarized as follows.1.The organic-inorganic hybrid lead halide perovskite nanowires and nanosheets were synthesized by ligand-assisted reprecipitation method.Through the observation of the sample in synthesis process,it was found that the formation of perovskite CH3NH3PbBr3 nanowires along the one-dimensional direction was most likely controlled by surface oleylamine ligands.And the CH3NH3 Pb I3 and CH3NH3 PbBrx I3-x nanowires were obtained by similar method.The surface photovoltage test showed that CH3NH3PbBr3 nanowires had stronger photogenerated voltage response than nanosheets.2.Polymethylmethacrylate and CH3NH3PbBr3 perovskite nanocrystal blends were obtained by post-treatment.It was found that the obtained blend film had well dispersed nanocrystals,good color purity and enhanced water stability.In this way,blending of polymethylmethacrylate on perovskite nanocrystals plays a waterproof barrier and prevents water from dipping into perovskite nanocrystals,which provides the possibility for industrial production of perovskite films.3.The perovskite nanocrystals coated with polymethylmethacrylate were prepared by introducing polymethylmethacrylate as ligand into ligand-assisted reprecipitation synthesis.The results showed that the functional groups of carbonyl groups in polymethylmethacrylate interact on surface lead to achieve full coverage of lead sites by this method.Hydrophobic framwork protected lead sites of hybrid organic-inorganic lead halide perovskite from occupation by water molecules.The interface layer formed in the composite film effectively prevented water permeating into the perovskite nanocrystals.The composite film exhibits significantly improved quality and highly stability,enhancing the exposure time under hydrothermal conditions.This approach provides a new idea for the protection of hybrid organic-inorganic lead halide perovskites based on polymer as a framework material,which can reduce surface defects and enhance the overall stability of the material by covering specific atoms with polymer functional groups. |
