Preparation And Optical Properties Of Micro/Nano Materials Based On Perovskite

The emergence of metal halide perovskite materials has completely changed many research fields,such as photovoltaics,light emitting diodes,micro/nano lasers,photodetectors,and x-ray imaging.The unprecedented performance achieved so far are related to the excellent properties of these materials,such as broadband high optical absorption density,long carrier lifetime,high photoluminescence quantum yield and narrow PL spectral line width.While,most of the research on perovskite materials are based on three-dimensional perovskites,such as Cs Pb Br₃.Due to the low quantum confinement effect of the three-dimensional perovskite,the three-dimensional perovskite material will undergo a serious Photoluminescence(PL)quenching phenomenon after losing the protection of ligand.The current research shows that reducing the dimension of the material to zero dimension is an effective method to solve the PL quenching.The strong quantum confinement effect caused by the high exciton binding energy of zero-dimensional perovskite materials prevents aggregation and quenching of zero-dimensional materials without ligand protection.Therefore,in-depth research on zero-dimensional perovskites will be promising.We take the zero-dimensional perovskite Cs₄Pb Br₆ as the main body of research to further explore it's optical properties and explore the potential applications of the material.At the same time,a preliminary attempt is made to replace the Pb element.The main findings are as follows:(1)In this study,pure zero-dimensional perovskite microrods were grown in the growth phase by the anti-solvent method.The developed Cs₄Pb Br₆ rod emits a strong green light,and its photoluminescence spectrum is distributed at?517 nm.Among the Cs₄Pb Br₆ bulk and microcrystals,the photoluminescence quantum efficiency is the highest,about 50%.Optical absorption spectrum and photoluminescence spectrum show that the green emission produced by Cs₄Pb Br₆ material is intrinsic luminescence.The observed light absorption and photoluminescence peaks can be attributed to the local[Pb Br₆]^4-octahedral confinement electronic transition,and the green photoluminescence comes from the defect energy level caused by the defect.(2)In this study,a size-adjustable Cs₄Pb Br₆ micron rod was synthesized by an anti-solvent method similar to the previous work.The potential of the developed Cs₄Pb Br₆ rod as an optical resonator is studied.Although dual-mode lasers have also appeared,single-mode lasers with high optical stability are preferentially observed.It is proved that by adjusting the polarization direction of the pump light relative to the longitudinal axis of the microrod,the laser generated by the microrod can be adjusted artificially(laser intensity and threshold).In addition,laser resonance can also be controlled by the length of the micro-rod.Finally,a single Cs₄Pb Br₆ crystallite was used to illuminate micro-scale objects to obtain speckle-free optical imaging,and the application prospects of the material in the field of speckle-free imaging were explored.(3)This study explored the possibility of replacing the lead element in lead-based perovskites,and prepared Cs₃Bi₂Br₉ micro-disks with controllable morphology by anti-solvent method.By adjusting the reaction concentration and temperature,the morphology was successfully adjusted.At the same time,the material has excellent stability.