Controllable Preparation And Optoelectronic Properties Of All-inorganic Metal Halide Perovskite Nanomaterials

With the rapid development of nanotechnology,low-dimensional semiconductor nanomaterials(including quantum dots,nanowires,nanoribbons,nanotubes,and nanocrystals)play a more and more important role in the field of new nano-optoelectronic devices.Many parameters affect the optical and electrical properties of semiconductor materials,such as luminous efficiency,absorption coefficient,carrier diffusion coefficient,carrier mobility.The bandgap width of semiconductors determines the absorption and emission properties of semiconductor materials,which further affects the application of semiconductor optoelectronic devices.Few kinds of semiconductors exist naturally in nature.Many limiting factors,the expenses of conventional semiconductor materials,large material size,the difficulty of application in integrated devices,still challenges the large-scale application of semiconductor nano-information devices.The bandgap limitation of traditional semiconductor materials seriously affects the development and application of multi-functional optoelectronic devices.Researchers have conducted many studies on bandgap modulation of different semiconductor materials to alleviate the bandgap constrictions.They have broadened the range of material bandgaps and provided the possibility for the future application of bandgap modulated semiconductors in integrated devices.There exists a critical need to explore the bandgap modulation of nano-structures to analyze the performance of semiconductors with graded or abrupt bandgaps in nano-optoelectronic devices.All-inorganic metal halide perovskite nanomaterials have shown excellent optoelectronic properties,specifically,(such as high optical absorption coefficient,long carrier diffusion length and lifetime,high carrier mobility,and tunable wavelength within the wavelength range of visible light with abundant material composition.This thesis improves the(CVD)experimental device of chemical vapor deposition.The all-inorganic metal halide perovskite materials with different bandgaps are successfully integrated on a single substrate.The heterojunction nanowires and nanoribbons with abrupt band gaps are produced.Specific research work is presented as follows:(1)The cesium-lead halide perovskite(Cs Pb X₃,X=Cl,Br,I)nanocrystalline structure is successfully prepared.The challenge that the solid reaction source material cannot be controlled in the vacuum tube furnace cavity is overcome by adding a stepper motor.The replacement of the reaction source material is completed under the condition of high-temperature growth.The continuous gradual change of Cs Pb Cl_3(1-x)Br_3xcomposition on a single substrate is realized.The bandgap modulation along the length of the substrate is completed.The tunable WGM nano-laser is produced.(2)Tin-catalyzed cesium-lead halide perovskite(Cs Pb X₃,X=Cl,Br,I)nanowires are successfully prepared under the action of the tin catalyst by exploring the growth conditions of all-inorganic metal halide perovskite nanowires,The reaction source is replaced by the improved chemical vapor deposition device.The preparation of Cs Pb Cl₃-Cs Pb I₃heterojunction nanowires is completed.The optical properties of the materials are studied.(3)The stepper motor is integrated on the original chemical vapor deposition experimental equipment to assist the movement of reaction source materials.The transverse heterojunction of Cd S-Cd S_xSe_1-x-Cd S alloy nanoribbons was prepared by a multi-step reaction.Under the irradiation of 405 nm laser,the nanoribbons emit red light in the middle and green luminescence on both sides with a"green-red-green"structure.The bandgap is modulated in the direction of the width of the nanoribbons.The semiconductor nanoribbon photodetectors are realized by using these unique structures.