Crystallization Mechanism, Performance Regulation And Application Of All-inorganic Perovskite Nanocrystalline Glass

All-inorganic perovskite nanocrystals(CsPbX₃,X=I,Br,Cl)are considered as light emitters for the next generation of light-emitting diodes due to their high photoluminescence quantum yield(PLQY),high luminous color purity and simple fabrication techniques.However,due to the characteristics of ionic crystals and low formation energy,its environment,water stability and thermal stability are very poor,which greatly limits its practical application.Glass is a stable carrier.It has been proven that the in-situ crystallization of all-inorganic perovskite nanocrystals in the glass can solve the problem of poor stability.However,the following problems still exist in all-inorganic perovskite nanocrystal glass:(1)The low luminous efficiency caused by low quantum yield;(2)The crystallization method is single and the mechanism is not clear;(3)The influence of glass network structure on its performance is unclear;(4)The application fields are narrow.In this article,we have prepared perovskite nanocrystal glass by high-temperature melting method,and adjusted it through the strategies such as ion doping.Finally we realize:(1)The improvement of quantum yield;(2)The mechanism's study of the crystallization inside the glass;(3)The exploration of the relationship between the glass network structure and its performance;(4)The expansion of application areas.The specific content includes the following four parts:1.A series of Li Br-doped CsPbBr₃NC glasses were prepared.A series of characterizations show that Li Br does not participate in the formation of the glass network structure,nor does it significantly change the glass structure.After doping,the quantum yield increase from 20%to 82%,which is one of the highest values of green emission based on CsPbBr₃NCs glass.At the same time,its stability has also been enhanced.The analysis shows that Li Br doping can enhance the bond energy of Pb-Br bonds,inhibit halide migration and reduce the generation of Br vacancies.Based on 7%Li Br-doped CsPbBr₃NCs glass,a white light-emitting diode(WLED)with excellent optical parameters is manufactured.2.A series of CsPbBr₃NC glasses doped with a large amount of Li⁺were prepared,which realize self-crystallization of CsPbBr₃NCs without heat treatment.Studies have shown that a large amount of Li⁺doping will change the network structure of the glass,resulting in an increase in the aggregation state in the glass.At the same time,the degree of phase separation of the glass increases.Both of these factors are conducive to the formation of CsPbBr₃NCs in the glass.The self-crystallized Cs PBbr₃NCs glass has better luminescence properties than heat treatment,and its PLQY can reach 40%.And it has good stability,especially thermal stability.The self-crystallized nanocrystal glass,blue and red commercial phosphors are combined together to construct a WLED with good application prospects.3.A series of CsPbBr₃NC glasses were prepared by adjusting the type and content of alkali metals in borosilicate glass.A series of characterizations show that adjusting the type and ratio of alkali metals can change the ratio of[BO₃]and[BO₄]and phase separation in the glass network structure.It has different effects on the precipitation,optical properties and stability of nanocrystals.Under the premise that the layered structure of[BO₃]is dominant,the increase in the degree of phase separation is conducive to the precipitation of nanocrystals.The CsPbBr₃NC glass containing Li Br and Na Br has better optical properties and more three-dimensional framework structures[BO₄]can improve the environmental,water and thermal stability of nanocrystals in glass.4.Combined with the excellent optical transmittance and stability of the glass,the application expansion and performance optimization of CsPbBr₃NCs glass as a scintillator for X-ray imaging have been realized.Finally,based on CsPbBr₃NCs glass,a spatial resolution of 11.0 lp/mm is obtained,and based on CsPbBr₃:Li Br NCs glass,a spatial resolution of 16.0 lp/mm is achieved,which is the record resolution of X-ray imaging based on perovskite scintillators so far.At the same time,we analyze the scintillation properties such as X-ray attenuation efficiency of CsPbB_r3NCs glass scintillator,and finally get the detection limit of 154?Gyair/s,which shows that CsPbBr₃NCs glass can be used as a scintillator in the field of X-ray imaging.