Preparation And Optical Properties Of Inorganic Lead-based Perovskite Materials

Perovskite material,which is a new type of widely studied photovoltaic materials,has excellent luminescence quantum yield,energy conversion efficiency,perfect crystal structure and a large number of free carriers,etc.Because of the low cost and high theoretical efficiency,perovskite material has been the hotspot in photovoltaic field recently.Inorganic lead-based perovskite material has excellent optical properties,such as adjustable luminous color,narrow luminous spectrum,low defect state density,etc.However,it has poor stability in air atmosphere,which is easily to be phase-change decomposed.Its commercial applications are also limited by the restricted preparation.Therefore,more research and exploration are needed.Based on the structure of perovskite material ABX3,different ions are substituted in different positions.The properties of ion-doped perovskite material are learned in this paper,which conclude the crystal structure,light absorption characteristics,thermal stability and its performance in fluorescence spectra and ray shielding.(1)First,inorganic lead-based perovskite material was prepared and characterized.The Br-was substituted by I-in the perovskite structure to improve the stability.The single crystal growth is carried out by the temperature-increasing method.This method is simple,efficient and easy to control.The influence of solvent,temperature and halogen atom doping ratio on the growth speed,morphology and stability of single crystal was studied.The results showed that CsPbBr3 perovskite single crystal grown at 160? using DMSO as solvent grows more slowly with the increase doping rate of iodine element,but the stability of the single crystal has been significantly improved.(2)Although the hybrid lead-based perovskite single crystal material significantly improves the thermal stability,it does not perform well in terms of photoluminescence.For single crystal materials,the growth temperature is a relatively large limitation,and it is difficult to adjust the light emission range.Therefore,this paper further studied the lead-based perovskite quantum dot material.For current synthesis method of lead-based perovskite quantum dot material,the thermal injection method is a relatively efficient and controllable method.In order to adjust the luminescence band gap and the luminescence range,Br-was instead by I-,Cl-to synthesize lead-based perovskite quantum dot materials by the thermal injection method.The study found that with the decrease of bromine element and the increase of iodine element,the luminous range of the material gradually shifted to red,and the direct band gap of perovskite material increased.It shows that the band gap can be easily controlled by adjusting the doping ratio of halogen elements to control the emission wavelength and meet the requirements of different devices.(3)In the research of lead-based perovskite materials,most of them were based on the field of photovoltaics.The lead element contained in lead-based perovskite materials is commonly used in y-ray shielding and the low atomic number elements can absorb neutrons.For this reason,BF4-ions was used to instead of the halogen ion,to make the perovskite material shield neutrons.Therefore,the lead-based perovskite material with BF4-doped can be applied in radiation shielding field.In this paper,the B-doped lead-based perovskite material was successfully synthesized.The contained boron(B)element can absorb thermal neutrons.The y rays were released after the neutrons were absorbed,while the contained lead(Pb)element can shield y rays.So,it could achieve a shielding effect of multiple rays.Through the study of characterization of perovskite materials with different B-doping ratios,the shielding performance on radiation could be obtained.