Study On Performances Of Photoelectric Devices Based On PEA Quasi Two-dimensional Perovskites

The organic/inorganic hybrid quasi two-dimensional perovskite materials have attracted widespread attention due to their excellent properties,such as high carrier mobility,high fluorescence quantum yield,relatively high exciton binding energy,adjustable energy band-gap,simple preparation process and so on.In addition,the multiple quantum well structure formed by alternately stacking organic layers and inorganic layers enables them to exhibit different photophysical properties.Based on the above characteristics,quasi two-dimensional perovskite materials have been widely used in solar cells,light-emitting diodes,photodetectors,laser devices,sensors and other optoelectronic devices.In this paper,the long-chain phenylethylamine（PEA）molecular was used as the organic layer,and lead bromide（Pb Br₂）was used to build the framework of the[Pb Br₆]inorganic layer.The effects of doped bromomethylamine（MABr）and cesium bromide（Cs Br）on the structure,photophysical properties of perovskite materials and the device performances were studied respectively.The main research contents are listed as follows:1.The PEA₂Pb Br₄+x%MABr（x=0,10,20,30,40,50,60,70,80）perovskites were synthesized by the solution process,and the perovskites films were prepared by the spin-coating method.The films were tested and characterized by XRD,SEM,AFM,UV-Vis,TRPL etc.Through analysis,we investigated the effects of different amounts of MABr in perovskites on their films’morphology,structure and photophysical properties.Meanwhile,the energy/charge transfer and recombination luminescence mechanism of perovskites films were also discussed.2.The perovskite light-emitting diodes have been prepared using PEA₂Pb Br₄+x%MABr（x=0,10,20,30,40,50,60,70,80）as the light-emitting materials,and the device performances were tested and analyzed.It was found that with the increase of MABr,the light-emitting colors of the devices gradually changed from deep blue to green in a broad range.The maximum luminance of the device increased from 47cd/m²at 10%MABr to 1572 cd/m²at 80%MABr.The maximum current efficiency of the device increased from 0.28 cd/A at 10%MABr to 3.83 cd/A at 80%MABr.Moreover,the organic orange-red fluorescent dye rubrene was doped into the pervoskites PEA₂Pb Br₄+50%MABr as the emitting layer,and the energy/charge transfer between different n phases of the emitting layer have been explored.By optimizing the device structure,a white LED was successfully fabricated with CIE coordinates of（0.339,0.327）at 9 V.3.The photodetectors based on PEA₂Pb Br₄+x%MABr（x=0,20,40,60,80）pervoskites as the photosensitive layer have been fabricated,and the influence of doping amount of MABr on device performances was analyzed.In order to improve the device performances,the perovskites PEA₂Pb Br₄doped with x%Cs Br（x=0,20,40,60,80）instead of MABr have been prepared,and the structure and photophysical properties of these perovskites were investigated.The corresponding photodetectors have been fabricated based on PEA₂Pb Br₄doped with x%Cs Br（x=0,20,40,60,80）.It was found that under the same doping ratio,the performances of photodetectors doped with Cs Br are generally better than those of the devices doped with MABr.The optimal device（40%Cs Br）showed a light response rate of 153.82 m A/W under 0 V bias and 400 nm（8 m W/cm²）light excitation,which was enhanced by 2.45 times compared to that of the control device.The light detection rate of the optimal device was 9.4×10¹⁴cm Hz^1/2/W,which was enhanced by an orders of magnitude compared to that of the control device.Meanwhile,the rise and fall times of the light response of optimal device were 42 ms and 53 ms,respectively,which were reduced by 14%and12%compared to those of the control device.