| All inorganic metal halide perovskite represented by Cesium lead iodine has excellent structure and photoelectric properties such as high carrier mobility,high optical absorption coefficient,high luminous quantum efficiency and great defect tolerance,showing great application potential in the development of high-performance electronic and optoelectronic devices.To realize its application in optoelectronic devices,on the one hand it is necessary to develop reliable methods to prepare large-area,high-quality metal halide perovskite materials,and on the other hand it depends on effectively controling the optoelectronic properties,and the generation,transport and recombination of carriers of perovskite materials.Therefore,in this paper,the all-inorganic cesium lead halide perovskite materials are taken as the research object,and the near-steady state source chemical vapor deposition（CVD）method is developed to systematically study the effects of alloy components and growth parameters on the crystal structure and optoelectric properties of perovskite.The interface effect on exciton luminescence characteristics and carrier dynamics of cesium-lead-iodide perovskite/gallium nitride heterojunction were explored.The main research contents were included as follows:1.The controllable growth mechanism of CsPb(I1-xBrx)3 perovskite material under different precursors’bromine/iodine composition ratio was systematically studied based on the near-steady source CVD method,and the influence of halogen alloy composition effect on its crystal structure and exciton luminescence characteristics was explored.The crystal phase,size and thickness of quasi-two-dimensional CsPb(I1-xBrx)3 perovskite are highly dependent on the bromine/iodine component ratio of precursor.CsPb(I1-xBrx)3 perovskite nanosheets can be transformed from orthogonal phase to cubic phase by the synergistic effect of precursor ratio and temperature.In addition,the band gap of perovskite can be continuously adjusted from 2.33eV to 1.75eV by changing the bromine/iodine component ratio,and the exciton luminescence peak can be continuously changed from 530nm to 710 nm.This work provides a basis for the energy band engineering of all inorganic metal halide perovskite materials and its application in photovoltaic and optoelectronic devices.2.High quality Cesium-lead-iodide perovskite nanosheets were epitaxial on gallium nitride substrate by one-step CVD growth method,and the effects of interface effect on the band structure,exciton luminescence,carrier lifetime and structural stability of cesium-lead-iodide/gallium nitride heterojunction were studied in depth.The results show that the heteroepitaxy cesium lead iodine nanosheets have orthogonal structure,and the exciton luminescence peak is 710nm.The cesium-lead-iodide/gallium nitride heterojunction shows a type Ⅱ band band order,which can greatly promote the separation of interface carriers,resulting in fluorescence quenching of cesium-lead-iodide perovskite and exciton lifetime shortening.Due to the complementarity of the band gap between cesium-lead-iodide perovskite and gallium nitride perovskite materials,the absorption spectrum of the formed heterojunction can be widened from visible to ultraviolet light.The research results provide important reference significance for the preparation of large mismatch gallium nitride heterojunction,and also lay a foundation for the application of cesium lead iodine/gallium nitride heterojunction in photovoltaic cells and photodetectors. |
