Study On The Preparation And Properties Of Perovskite Transistors

Perovskite to Russia mineralogist L.A.Perovski naming,initially perovskite was composed of CaTiO₃,the term later extended to the similar perovskite crystal structure of materials,such as methylamine lead iodine?CH₃NH₃PbI₃?.CH₃NH₃PbI₃ band gap width is about 1.5 eV,high carrier mobility and carrier diffusion distance is long?>100?m?,bipolar transmission characteristics,in the light of the visible light range with high absorption rate and its rapid development in the field of solar cells.These make it has quickly become one of hot research materials in the perovskite materials.CH₃NH₃PbI₃material preparation of low cost,simple preparation method,do not need high temperature treatment,but its phonon scattering,ion drift and molecular polarization are serious,to obtain the transistor characteristic is very difficult,and low cost low temperature preparation of small size,high stability,mobility,two-dimensional plane of the structure of the transistor is crucial to the development of the electronic information industry,so the preparation and research based on the two-dimensional CH₃NH₃PbI₃transistor devices was of great significance.In this paper,on the basis of predecessors'work,first with water bath supersaturated crystallization precursor for synthesis of perovskite?PbI₂?,the preparation of optical detector based on PbI₂,and carries on the research,by CVD method its PbI₂ into two-dimensional perovskite microcrystalline,preparation based on two-dimensional perovskite microcrystalline transistor,and study of features,this thesis mainly research contents are as follows:?1?Two dimensional PbI₂ monocrystals were prepared by the method of water bath supersaturated crystallization,and the size of the growth crystal was found between 20and 500 nm,and the thickness of the growth crystal was between 15 and 160 nm.The size and thickness of the growth crystal are consistent with the gauss curve.The photoconductive detector based on two-dimensional PbI₂ single crystal was prepared,and its photosensitive properties were studied.It was found that the device had obvious response to the wavelength range of 400-530 nm,and the corresponding gap width was2.34 eV.?2?Using the method of chemical vapor deposition?CVD?,make the ammonium methyl iodide?MAI?and lead iodide nano reaction in tubular furnace,generate two-dimensional microcrystalline perovskite,and carries on the characterization,statistical analysis,found the iodide lead after into perovskite,surface roughness and thickness were significantly increased.The surface roughness was changed from 1.07nm to 17.8 nm.The thickness changed from 23 nm to 100 nm.?3?By CVD method based on two-dimensional CH₃NH₃PbI₃ microcrystalline transistor,study the transistor characteristic,it is concluded that based on two-dimensional CH₃NH₃PbI₃ microcrystalline transistor,the field effect mobility is0.13 cm²/V?s,threshold voltage to-12 V,the threshold swing 8.7 x 10^-4mV/dec,switch ratio is 1.25.?4?The heterogeneous junction of WS₂/PbI₂ was prepared by CVD method,and the thickness increased as the growth time passed by when the PbI₂ grew on the WS₂substrate.The PbI₂ first grew on the edge,then in the center nucleus,where the nucleation shaped for the dendrite extended to the edge,transforming into the film.The PL peak position of the heterogeneous junction is red-shifted with the increase of the PbI₂ thickness.The detector of the heterogeneous junction shows the characteristic of the diode,which responded obviously to the violet.Under zero bias,lighting with the laser irradiation of 405 nm,there is a significant negative photoconductive effect between the source leakage electrode of the device,while the photoelectric current becomes positive in the positive bias,the mechanism needs further study.