| Organic-inorganic hybrid perovskite materials are a new type of optoelectronic materials with excellent photoelectric properties,making them widely used in photodetectors,light-emitting diodes,solar cells,lasers and other fields.Three-dimensional perovskite materials have small exciton binding energy,strong and wide visible light absorption energy and high carrier mobility,but due to their poor environmental stability,the practical application of three-dimensional perovskite materials is largely limited.Compared with three-dimensional perovskite materials,two-dimensional perovskite materials have higher stability,low defect density,and quantum confinement effects.They have important research value in practical applications such as miniaturization,portable,and flexible wearable devices.It has bright development prospects.Therefore,it is of great scientific significance to study the structure and corresponding optical and electrical properties of two-dimensional perovskite materials.Compared with thin films,microcrystalline materials have small grain boundaries and have lower defect density,which can directly reflect the structural characteristics of the material.High-quality perovskite microcrystalline are useful for evaluating its intrinsic properties,including electrical conductivity,ferroelectric hysteresis,charge mobility,The carrier diffusion length is of great significance.In this work,the luminous efficiency and electrical conductivity of perovskite microcrystalline materials are improved by ion doping.The main contents are as follows:(1)An intrinsic two-dimensional perovskite(PEA)2Pb(Br1-xClx)4 single crystal material doped with Cl ions was prepared by the cooling crystallization method.SEM,EDS,XRD and other structural characterization results proved:Cl-doped causes distortion of the crystal lattice.The difficulty of crystal growth increases and the growth quality decreases as the proportion of doping of Cl-increases.This conclusion provides various basic researches for understanding the structure and crystal growth mechanism of perovskite crystals.According to performance characterization results of ultraviolet-visible light absorption spectrum,photoluminescence spectrum,photoluminescence efficiency,fluorescence lifetime spectrum,etc,it is proved that:doping is realized adjustability of the band gap and wide band gap luminescence,and the appropriate amount of doping ratio can improve the optical performance to a certain extent,laying the foundation for the research of high-efficiency white light-emitting diodes.(2)A quasi-two-dimensional layered perovskite(PEA)2(MA)n-1PbnBr3n+1(PEA corresponds to phenylethylammonium)microcrystalline material was prepared by the anti-solvent diffusion method,and the number of layers of the perovskite inorganic layer was determined the values of n are 1,5 respectively.Through microcrystalline analysis,SEM,EDS,XRD structure characterization of(PEA)2(MA)n-1PbnBr3n+1(n=1,5)microcrystalline,it is proved that(PEA)2(MA)n-1PbnBr3n+1(n=1,5)microcrystalline layered structure,and(PEA)2(MA)4Pb5Br16(n=5)microcrystalline structure is(PEA)2PbBr4(n=1,the intrinsic two-dimensional perovskite structure)and MAPbBr3(n=?,the three-dimensional perovskite structure)structure competition under the mixed phase.The high-quality microcrystalline replaces the traditional mask with a copper mesh,and evaporates Au electrodes to make a horizontal photodetector.Analysis of its I-V curve shows that:(PEA)2(MA)4Pb5Br16(n=5)microcrystalline has better current on-off ratio,light detection rate,and light response rate than intrinsic two-dimensional perovskite(PEA)2PbBr4(n=1)microcrystalline material,which proves that the increase in the number of inorganic layers in the two-dimensional layered perovskite microcrystalline material will weaken the quantum limit of the two-dimensional perovskite microcrystalline material,weakening the exciton binding energy,the electron-hole pairs are easier to separate under the applied electric field,and the conductivity increases.It reveals the carrier transport characteristics of the quasi-two-dimensional mixed-phase organic-inorganic hybrid perovskite,provided the efficiency photodetector ideas on reseaching. |
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