The Study On Photodetector Based On Organic-inorganic Hybrid Perovskite MAPbX₃(I,Br) Single Crystal

In recent years,photodetectors have been widely used in the fields of fiber optic communication,image sensing,machine vision,environmental monitoring,and biological detection,and their functions have received more and more attention.At present,most perovskite photodetectors are based on polycrystalline thin films.However,the large number of grain boundaries and defects in polycrystalline thin films severely restrict the detection performance of the device.Compared to polycrystal,the single crystals of perovskite have the advantages of long diffusion length,high mobility,few defects,and good stability,which provides the possibility for the development of more excellent photodetectors.In this paper,MAPbX₃(I,Br)single crystals were successfully grown by using the temperature-up crystallization method.Besides,we used MAPbBr₃ as the core and MAPbI₃ as the shell to grow MAPbBr₃I_3-x crystals,and then a pair of gold electrodes was evaporated on the two(100)faces of these three single crystals to fabricate photodetectors.Experimental data shows that the MAPbI₃ photodetector has excellent performance under the irradiation of different wavelengths of incident light,and has the largest photoresponsivity of 7 A/W and the highest external quantum efficiency of1333%among these three photodetectors.Because the absorption edge of MAPbBr₃is570 nm,its photodetector has excellent photoresponsivity of 5.1 A/W and external quantum efficiency of 1004%only at 405 nm.The photoresponsivity and external quantum efficiency of the MAPbBr₃I_3-x photodetector are totally common.In addition,we also evaporated three metals with different work functions to investigate the effect of electrode materials on the performance of the vertical structure MAPbI₃photodetector.Through analysis,it was found that the dark current of the photodetector fabricated with copper electrode was the smallest of 0.06?A,which was very effective in suppressing the dark current of the device,and the gold electrode helped most on the dissociation of the photoexcitons inside the photodetector,the photoresponsivity and external quantum efficiency of the photodetector are 3.9 A/W and 745%,respectively.