Exploration And Application Of Inorganic Cuprous Halide Self-trapped Exciton Luminescence Materials

In recent years,metal halide perovskite materials have attracted much attention because of their simple preparation,tunable emission,high optical absorption coefficient and good charge mobility.However,the toxicity of lead and the instability of structure hinder the development of this kind of materials,so it is of great significance to develop lead-free metal halide perovskite materials.Copper has abundant reserves,environmental friendliness and low cost.In addition,Cu⁺has a small ionic radius which makes it easier to form a low-dimensional structure.It is worth nothing that low electron dimension inorganic copper（I）metal halides（Cu（I）MHs）inherit the excellent luminescent properties of perovskite and reduce toxicity and the luminescence of which is mainly derived from self-trapped excitons（STEs）.This type of emission with the characteristics of broadband emission and high luminous efficiency,making it an ideal solution for single substrate,white solid state light source.However,few Cu（I）MHs materials have been reported and their poor water stability seriously hinder their application.Based on this,the research content of this thesis mainly includes two parts:one is to explore the synthesis of new low dimensional Cu（I）MHs materials with excellent performance;the other is to improve the water resistance of Cu（I）MHs material by coating,and expand its application field.Specific research works are as follows:（1）We have explored synthesis new Cu（I）MHs by high temperature solid phase method,and investigated the effects of calcination time and temperature on material synthesis.Two kinds of Cu（I）MHs,Rb₄Cu₅Cl₉and Cs_0.55Rb_0.45Cu₄Cl₃(I_1.9Cl_0.1),were synthesized and characterized preliminarily.It provides experience for exploring Cu（I）MHs with excellent performance.（2）Cuprous halide composites（Cu（I）HC）containing CsCu₂Cl₂I,CsCu₂Cl I₂,and Cu I phases were synthesized by high temperature solid state method.Under the irradiation of285 nm UV light,the emission wavelength of CsCu₂Cl I₂located at 475 nm with a full width at half maximum of 99 nm.Cu（I）HC can also emit near white and purple light when the excitation wavelength in the range of 250～360 nm.After coating with polysiloxane,the water stability of Cu（I）HC has a qualitative leap,which provides a new way to improve the water stability of Cu（I）MHs.Based on this discovery,near-white light emitting Cu（I）HC polysiloxane luminous ceramics（PSOLCs）for LED were prepared,which not only improved the water resistance of Cu（I）MHs,but also endowed them flexibility,and greatly expanded their application field.