Controllable Synthesis And Applications Of High-Quality All-Inorganic Lead Halide Perovskite Nanocrystals

Since the pioneering work was reported in 2015,all-inorganic lead halide perovskite(CsPbX3,X=Cl,Br,I)nanocrystals(NCs)have attracted widespread attention due to their high photoluminescence(PL)quantum yield(PLQY),narrow emission width,tunable emission range,high carrier mobility and facile preparation process.They have been widely applied to solar cells,light-emitting diodes(LEDs),photodetectors,lasers and so on.Although great progress has been achieved in the research of CsPbX3 NCs,there are many challenges at this stage.On one hand,because of their intrinsically ionic feature and dynamic bonding between CsPbX3 NCs and capping ligands,CsPbX3 NCs are easily destroyed in ambient environment under the effect of water,oxygen,light,or thermal treatment.Especially for low-dimensional CsPbX3 NCs,their low stability has become a big concern and may impede their practical applications.On the other hand,developing CsPbX3 NCs to other areas,such as smart materials and rapid detection,is another issue that we are focusing on.In order to solve these problems,we provided a strategy to prepare CsPbX3 NCs with outstanding optical properties and high stability.Furthermore,the applications of CsPbX3 NCs for smart fluorescent materials and lead ions detection were successfully realized.The detailed research contents are as follows:1.A post-treatment method was demonstrated for the preparation of CsPbX3 ultrathin nanowires(NWs).CsPbBr3 nanocubes would transform to CsPbX3 ultrathin NWs under thiourea treatment.In this process,a consecutive interfacial transformation of CsPbX3→ Cs4PbX6→ CsPbX3 was systematic studied,and the corresponding morphology variation mechanism was explored.Thiourea played an important role in obtaining CsPbX3 ultrathin NWs with high PLQY and high resistance to water.2.A reversible fluorescence switching material was prepared based on the CsPbI3 NCs.The CsPbI3/AgI composite was formed by introducing photochromic AgI NCs to CsPbI3 NCs.And the PL quenching and recovery of CsPbI3 NCs were essentially realized by the decomposition and generation of AgI under light regulation,in which the reversible formation and destruction of Ag-CsPbI3 heterostructures were controlled.This CsPbI3/AgI system could be successfully applied to rewritable platform3.A simple paper sensor loading CsX was developed for qualitative and quantitative analysis of lead ions(Pb2+)in water.Based on the crystallization of CsPbX3 NCs,the paper sensors after Pb2+ detection showed visible variation of luminescence,and a good linear relationship between their PL intensity and Pb2+ concentration was established.This green method exhibited high selectivity,low cost,good portability.