Preparation And Luminescence Characteristics Of Zero-dimensional Guanidine Manganese Bromide Scintillator With Antithermal Quenching

Organic-inorganic hybrid metal halide materials have designable optoelectronic properties,high carrier transport properties and special defect tolerance,making them excellent candidates for many important optoelectronic fields.Such as solar cells,light-emitting diodes,lasers,and scintillators.However,there are still some challenges in the research and application of metal halides.For example:（1）The most widely studied metal halide is lead-based halide.The toxicity of lead has a serious impact on human life and the environment,limiting its commercial application.In the past,many groups used low-toxic or non-toxic elements（such as Sn,Bi,Sb,Cu,and Ge）to replace lead to synthesize a series of lead-free metal halides.However,the latest research on lead-free perovskites is mostly in the material development stage,There are still many shortcomings in the understanding of its light-emitting mechanism and application performance;（2）At present,only a few researches are carried out on the application of low-dimensional metal halides to flexible devices.However,with people’s understanding of flexible devices With the increase in demand,it is imperative to develop materials with excellent integration performance of flexible devices;（3）Low luminescence performance at room temperature/high temperature:The luminous efficiency of metal halides usually decreases obviously as the working temperature rises,which is not conducive to its commercial application.In order to solve these problems,we discussed from the following aspects:（1）In order to solve the problems of lead toxicity and flexible application,we prepare(C₁₃H₁₄N₃)₂Mn Br₄single crystal with a recorded high photoluminescence quantum yield of 98.6%by slowing cooling the supersaturated solution.The intrinsic properties of its single crystal structure,photophysical properties and scintillation performance are systematically studied,and its scintillation performance is optimized by heavy ion doping.The obtained(C₁₃H₁₄N₃)₂Mn Br₄:14%Cd single crystal has a high light yield of 26306 Ph Me V-1.In addition,we also ground the prepared single crystal powder and mix it with PDMS to prepare a flexible composite film for X-ray imaging applications,with a resolution of 2 lp/mm.（2）In order to solve the problem of thermal stability,this paper conducte an in-depth study on the thermally dependent fluorescence of(C₁₃H₁₄N₃)₂Mn Br₄single crystal,and find that it has an excitation wavelength-dependent antiquenching resistance under UV-Vis light,and explain the phenomenon mechanism.We believe that there is a defect energy level between the two excited state energy levels of Mn²⁺.When excited at the"valley"wavelength of the PLE curve,electrons are trapped by the defect energy level and require thermal energy to assist in the transition.However,but when excited at the"peak"wavelength of the PLE curve,there is no needs to consider this issue.Finally,we prove that this property is universal in zero-dimensional Mn²⁺-based bromide.In addition,the material also exhibits antithermal quenching under X-rays,which is beneficial to its scintillation applications.