One-dimensional Perovskite Single Crystal DMEDAPbBr₄ Photoluminescence Color Characteristics And Regulation Mechanism

Organic-inorganic hybrid metal halide perovskites are widely used in optoelectronic devices due to their excellent photophysical properties,including high light absorption,long carrier lifetime,long diffusion length,and band structure tunability.Among them,one-dimensional perovskite crystals are ideal luminescent materials for tunable color emission due to their good morphology,high quantum efficiency,and broadband white light emission properties.DMEDAPbBr4 perovskite single crystals are one of the promising photoelectric conversion materials with broadband white light emission properties and fluorescence quantum yields over 20%.Studying the changes of its internal carriers and energy can deeply understand the process of the luminescence mechanism.On this basis,the internal process can be further regulated,and then the fluorescence color of the one-dimensional perovskite crystal can be adjusted,which is the color change of the perovskite material.It provides new ideas in the application of light-emitting devices.In this paper,DMEDAPbBr₄ one-dimensional perovskite single crystal and its corresponding manganese-doped material were successfully prepared by anti-solvent vapor diffusion method.The fluorescence color of the material can be controlled by three means of temperature,doping and polarization.The main experimental results obtained are as follows:(1)The fluorescence emission color of the one-dimensional perovskite DMEDAPbBr₄single crystal was regulated by temperature adjustment.The evolution process of the crystal fluorescence color from yellow-green to blue-green was observed,and the fluorescence spectrum center occurred with the increase of temperature.The blue shift,which is responsible for the change in fluorescence color,occurs because the temperature-induced lattice deformation affects the positions of the valence and conduction bands.The fluorescence spectrum and lifetime of the temperature-changing process were collected,and the change of fluorescence spectrum intensity with temperature was studied.It was proposed that there was a thermal activation process between free excitons and trapped excitons and the occurrence of non-radiative recombination of trapped excitons.This temperature-controlled fluorescence color change makes the one-dimensional perovskite DMEDAPbBr₄single crystal have potential applications.(2)Controlling the photoluminescence color of one-dimensional perovskite single crystals by manganese ion doping.In Mn-doped DMEDAPbBr₄ 1D perovskite single crystals,a reversible and continuous emission color change between orange and blue is achieved by tuning the excitation repetition rate and pulse intensity.Through temperature-varying fluorescence spectroscopy experiments,it was verified that the saturation of Mn²⁺is the result of the complete excitation of the Mn dopant under high excitation light flux,and is not a defect-mediated cause,nor is it caused by the annihilation of multiple excited Mn²⁺.Mn-doped one-dimensional DMEDAPbBr₄ perovskite single crystals exhibit stable color-tuning properties.(3)Controlling the photoluminescence color of one-dimensional perovskite single crystal DMEAPbBr₄ by polarization.Due to the anisotropy of the transition dipole moment caused by the asymmetric crystal structure,the fluorescence of one-dimensional perovskite single crystal has a very obvious linear polarization,and the fluorescence of different polarization directions is different in intensity and spectral center.By adjusting the polarization angle,fluorescence with different emission colors can be obtained.The growth direction of the crystal has an effect on the polarized fluorescence and the polarized fluorescence along the crystal growth direction is the strongest.In addition,low temperature can affect the polarized fluorescence of the crystal,even flipping the polarization direction of the strongest fluorescence by 90 degrees.The study of the fluorescence response of one-dimensional perovskite single crystal DMEDAPbBr₄ to polarization is a work of practical significance.