Controlled Fabrications Of Organic-inorganic Layered Perovskite Nanowires And Study On Mechanism

Organic-inorganic layered perovskite are increasingly attracting widespread attention due to its excellent photoelectric properties and potential applications in optoelectronic devices.It has become a very hot issue on how to synthesize large scale uniform organic-inorganic perovskite nanomaterials and to reveal the formation mechanism of nanowires.In this dissertation,suitable organic and inorganic components were chosen to investigate the preparation methods of organic-inorganic perovskite nanowires,formation mechanism and stability at room temperature under the interaction of multicomponent solvent.First of all,one-step method has been used to prepare impurities perovskite nanowires,meanwhile its preparation process has been discussed.Then,a large amount of high conversion rate of pure perovskite nanowires has been synthesized by two-steps method.The synthetic mechanism of the nanowires and the stability of the material has been well studied at the same time.In addition,replacing the organic and inorganic components could obtain similar perovskite nanowires.We had made some important achievements which are as follows:?1?We chose lead iodide?PbI2?,a layered molecule,to serve as the inorganic components and chose methylamine iodine molecules?MAI?to serve as the organic components,which could formed the CH₃NH₃PbI₃ nanowires by self-assembly process and solvent effect.The perovskite dissolved in good solvent would gradually precipitation nanomaterials under the bad solvent dropped dropwise through one-step method,which leads to perovskite nanowires mixed with lead iodide.By two-steps method,it first formed Pb-containing intermediates,which then converts into perovskite nanowires by reacting with methylamine iodide solution.In two-steps,we got two different Pb-containing intermediates,one is PbI2-DMF nanowire and the other is PbI2 nanowire.The convert rate from the lead powder to lead iodide nanowire could reach up to 90.84%;The corresponding CH₃NH₃PbI₃ nanowires with different surface morphology exhibit good stability at room temperature.During these synthesis processes,the layered structure and the solvent effect play important role in the formation of nanowires,thus we put forward the possible reaction mechanism.?2?We chose lead bromide?PbBr2?,to serve as the inorganic components,methylamine bromide molecules?MABr?to serve as the organic components and bromide cesium to serve as small inorganic molecule,which could form the different surface morphology of CH3NH3PbBr3 nanowires and CsPbBr3 nanowires through two-steps preparation.These conversion processes followed the proposed reaction mechanism,which indicates that the reaction mechanism is the universality to form organic-inorganic perovskite nanowires.In addition,doped perovskite could be obtained by mixing the intermediate nanowires with different ratio of ammonium salt.The CH₃NH₃PbI₃ nanowires,CH3NH3PbBr3 nanowires and doped perovskite CH₃NH₃PbI_xBr_3-x have different maximum absorption wavelength,which contributes to the best use of the sunlight when these products were put into series.