Preparation And Photonic Properties Regulation Of 1D/2D Cesium Lead Bromine Perovskites

Perovskites have become one of the most promising new semiconductor materials today due to their superior optical properties,high fluorescence quantum yield,high carriers mobility.Organic-inorganic hybrid perovskites are widely used in solar cells and show high conversion efficiency.However,the environmental and thermal stability of organic-inorganic hybrid perovskites greatly limit its development.The all-inorganic perovskites had stands out on this basis.The stronger exciton emission,lower density of defect states,higher environmental and thermal stability provides an important materials basis for the development of perovskites,become an important element of the next generation of optoelectronic devices.However,the current research on the luminescent properties of all-inorganic perovskites still in its infancy and still many difficulties in the study of the photonic properties.On this basis,this paper studied the photonic properties of CsPbBr₃ and CsPb₂Br₅ structures,and explored the physical mechanism of their luminescence.This work is divided into the following two aspects:?1?The photonic properties regulation of CsPbBr₃.The high-quality CsPbBr₃ micro/nanowires used the solution method to prepare,and demonstrated by X-ray diffraction?XRD?,scanning electron microscope?SEM?,energy dispersive spectroscopy?EDS?,Raman spectrometer and other characterization methods.The CsPbBr₃ we prepared has well characteristics with high crystal quality,well morphology and high stability.The temperature-dependent Raman was used to explain the reasons for the changes in peak strength,peak position,and full width at half maximum with the temperature,as well as a phase transition at low temperature.The laser power-dependent PL,temperature-dependent PL and PL lifetime curves were used to observe the in-situ triplet exciton emission and its blueshifts,the end cavity related emission bands and its redshifts.Thus,two strong coupling effects exist in the system:The exciton-photon coupling and exciton-phonon coupling work together to control the luminescence of CsPbBr₃.?2?The photonic properties regulation of CsPb₂Br₅.A large scale CsPb₂Br₅ can be prepared by solution methods.The synthesized high-quality CsPb₂Br₅ micro/nanosheets were characterized by XRD,SEM,EDS,EDS-Mapping,Raman spectrometer and other characterization methods.It is confirmed that the CsPb₂Br₅ exhibits bright green emission from non-luminescence by the UV laser.Transmission electron microscope?TEM?,photoluminescence,the carriers lifetime and Raman spectrum studies have confirmed that green emission comes from CsPbBr₃.X-ray photoelectron diffractometer?XPS?further determined the sensitive transition between CsPb₂Br₅ and Cs Pb Br₃ due to heating and humidity.Futher realized the control of green emission with lighe/heating/humidity.Finally built the CsPb₂Br₅ and CsPbBr₃ heterojunction devices and verified the its good rectification characteristics.In summary,we have prepared CsPbBr₃ and Cs Pb₂Br₅,and characterizated their photonic properties,explained their luminescence mechanism in detail,and realized the photonic properties regulation,futher providing an important foundation for the theoretical researches and applications of 1D/2D all-inorganic cesium lead bromine perovskites.