Preparation And Optical Properties Of Two-Dimensional Metal Halide Perovskite Films

Two-dimensional metal halide perovskite is a collective name with the structure?RNH₃?₂?CH₃NH₃?_n-1A_nX_3n+1,where n?integer?is the number of metal cation layers between two organic chains,when n=1 is a standard two-dimensional perovskite structure,n=2,3,…is a quasi-two-dimensional perovskite.Perovskite is a new generation of semiconductor materials.Compared with traditional semiconductors,it can achieve the adjustment of the emission wavelength in the visible light?400-800 nm?range.Changing the dimensions of perovskite can correspondingly change its quantum confinement effect.Decreasing from the high dimension to the low dimension can significantly increase the exciton binding energy of the perovskite material.At the same time,the perovskite material also has a non-linear effect and so on.In recent years,the application of perovskite materials involves various fields such as perovskite solar cells,light emitting diodes,field effect transistors,Bose-Einstein condensation,photocatalysis,and so on.Compared to three-dimensional perovskite materials,the layered RPPs naturally form semiconductor quantum well structures due to the large dielectric contrasts between the organic and inorganic layers,and the exciton binding energy is quite large,typically in the range of several hundred meV.Therefore,the Ruddlesden–Popper perovskites are not only of fundamental interest in light-matter interaction,but also important for applicable and high-performance optoelectronic devices.Therefore,two-dimensional perovskite is not only the basis for the interaction between light and matter,but also has great significance for high-performance and applicable optoelectronic devices.This article first introduces the structure classification,characteristics and perovskite devices of perovskite.Secondly,the method of synthesizing high-quality perovskite and its basic optical characterization are introduced.Then,the thickness-and temperature-dependent reflection spectrum of the two-dimensional perovskite film was analyzed,and the existence of Fano resonance was confirmed in the reflection spectrum.Next,we analyze the necessary conditions to achieve the strong coupling phenomenon.Finally,we prepared and planned for the strong coupling phenomenon on the DBR substrate.The main research contents of this article are as follows:1.A high-quality two-dimensional perovskite film was synthesized by the solution-processed spin-coated method.We obtained the perovskite thin film by the solution-processed spin-coated method.Using the controlled variable method,when the speed of the homogenizer is 5,000 rpm,the quality of the two-dimensional perovskite film obtained is the best.And for different thickness of perovskite thin film can be achieved by changing the"concentration"variable.2.The basic characterization method was used to prove the synthesized high-quality two-dimensional perovskite thin film.We first used SEM to observe the surface morphology of the synthesized two-dimensional perovskite films.Secondly,the distribution of synthetic elements was characterized by EDS spectroscopy,which proved that various elements were uniformly distributed in the perovskite film.Then,we used AFM to obtain the root mean square of the two-dimensional perovskite film of¹3 nm,which further proved that we synthesized a high-quality two-dimensional perovskite film.Finally,we used cross-sectional SEM to determine the thickness of the perovskite.3.Thickness and temperature-dependent reflection spectrum analysis.We first analyzed the perovskite film with a thickness of 50 nm.Due to the strong photons and excitons interaction?exciton-polarons?,a sharp single peak exists in the reflection spectrum of the 50 nm perovskite film.As the thickness changes from 70 nm to 420 nm,an additional dip appears in the transverse and longitudinal exciton energy of the reflection spectrum,and we proved that this was due to Fano resonance.This Fano resonance arises from the destructive interference of discrete exciton modes and continuous background reflection modes.Finally,we analyzed the temperature-dependent reflection spectrum characteristics,and proved that due to the decrease in temperature,the resonance broadening of the exciton became weaker so that the transverse-longitudinal exciton energy became smaller with decreasing temperature.4.Analysis of the necessary conditions for strong coupling on two-dimensional perovskite films.First,we verified the correctness of the shape of the reflection spectrum obtained on the glass substrate on the Ag film.Secondly,our analyzed of the angle-resolved reflection and PL spectrum on a glass substrate proved that it is difficult to achieve a strong coupling phenomenon on a bare glass substrate.Finally,we prepared and planned for the strong coupling phenomenon on the DBR substrate.