| The inorganic perovskite material bromine lead bismuth?CsPbBr3?has received extensive attention in various fields due to its special physical and chemical properties.The most interesting of these is its application prospect as a material for high-energy ray detectors.The high-energy ray generally consists of photons containing energy of the order of keV to MeV,and the CsPbBr3 single crystal has excellent optoelectronic properties.These characteristics determine that CsPbBr3 is suitable for the preparation of high-energy ray detectors.The main research contents of this paper include three aspects:one is to use two melting methods to grow high-quality CsPbBr3 single crystals,and the quality of single crystals is detailed.Based on the test characterization and analysis,the two methods were compared.The second is the characterization and analysis of the performance of CsPbBr3 single crystal as a high-energy ray detector.The third is the research of ionic transport characteristics of CsPbBr3 single crystal.We studied the temperature gradient and growth rate which are most suitable for horizontal moving melting zone method and vertical Bridgeman method.The optimized temperature for the horizontal moving melting zone method should be set to 640650?and the optimized growth rate is 0.48mm/h.The optimized temperature gradient for the vertical Bridgeman method is 9?/cm,and the optimized growth rate is 0.48mm/h.Then the structure,optical,carrier transport characteristics and electrical properties of the two melt-grown CsPbBr3 single crystals were studied.The results showed that high crystalline quality of CsPbBr3 crystals was obtained.The infrared transmittance was up to 75%and the UV transmittance was up to 40%.The forbidden band width obtained by fitting the ultraviolet-visible light transmission spectrum and the forbidden band width obtained by the PL photoluminescence spectrum are close to the theoretical value of 2.25eV,indicating that the crystal has no obvious defect level.The radiation composite carrier lifetime of CsPbBr3 single crystal is up to 129.4ns according to the results of TRPL time-resolved photoluminescence spectrum.The carrier mobility lifetime product is up to 9.8×10-4cm2/V according to the improved Hetch equation.And the highest resistivity is close to the order of 10G?·cm.For the high-energy ray detection performance of CsPbBr3 single crystal,we studied the response to X-ray?30keV?and?-ray 241Am?59.54keV?,respectively.CsPbBr3 single crystal has obvious response to X-rays.We calculated the sensitivity and gain factors.But the response to gamma rays is weak,and the Gaussian waveform of the signal is observed only by the oscilloscope.Finally,the ionic transport of CsPbBr3 single crystal grown by vertical Bridgeman method is studied in detail.It is well known that ABX3 type perovskites have ionic migration phenomena,exhibiting obvious DC polarization and I-V hysteresis effects,which adversely affect the stability of the device.The ionic migration activation energy Ea of CsPbBr3 single crystal was studied by the temperature-dependent I-t curve method,and it is compared with the theoretically calculated values in the literature.Combined with the previous research on the intrinsic defects of CsPbBr3 single crystal,the main object of migration was determined to be VBr.And we make a reasonable guess on the migration path of VBr.At the same time,we studied the temperature-dependent dielectric-frequency spectrum of CsPbBr3 single crystal.The macroscopic polarization phenomenon was studied from the dielectric properties and the mechanism was analyzed with theoretical models. |
PDF Full Text Request