Study On Photoelectric Properties Of Perovskite Light-Emitting Diodes Based On Composite Hole Transport Layer

Organometallic halide perovskite is a new type of solution-processable semiconductor material with high fluorescence quantum yield,high color purity,adjustable energy band,low temperature and large area preparation,etc.Thus,it shows great application prospects in light-emitting devices?LEDs?.However,there are some problems in perovskite light-emitting diodes?PeLEDs?as follows.Firstly,there are many pin-holes and high defect density in the perovskite thin film prepared by the single-step spin coating method.Secondly,Carrier transmission mismatch.Therefore,how to improve the quality of the perovskite thin film and enhance the transport capacity of the hole transport layer becomes crucial.This paper takes the perovskite material MAPbBr₃ as the research object,and improves the manufacturing process of the perovskite film by introducing metal oxides,two-dimensional materials to the hole transport layer in order to improve the photoelectric performance of PeLEDs.The main research contents of the paper include the following three parts:Frist,the preparation parameters of the perovskite light-emitting diode was optimized,and multiple spin coating method was used to improve the quality of the perovskite film and the photoelectric performance of PeLEDs.The influence of the concentration of the perovskite precursor,the molar ratio of MABr:PbBr₂ and the annealing temperature on the quality of the prepared MAPbBr₃ film was studied.The results indicate that the optimal concentration of perovskite is 5%,the molar ratio of MABr:PbBr₂ is 2:1,and the annealing temperature is 80?.On this basis,the paper characterizes the perovskite thin film prepared by multiple spin coating methods,analyzes the electrical properties of the PeLEDs device under multiple spin coating methods,and finds that the optimal spin coating frequency is 3 times under this condition.The device has the maximum luminence of 2053 cd/m²,and the maximum external quantum efficiency of 0.2%.The experimental results show that multiple spin coatings can improve the coverage and crystalline quality of the perovskite film and improve the electrical performance of the device.Secondly,Molybdenum trioxide?MoO₃?was introduced into PEDOT:PSS to construct a composite hole-transporting layer,and the effect of this method on the quality of perovskite films and the performance of PeLEDs devices was studied.The optimal volume ratio of PEDOT:PSS and molybdenum trioxide is 1:0.02.Under this condition,the quality of perovskite crystals is the best,and the luminence and current efficiency of PeLEDs are the largest.The maximum luminence reaches 5044 cd/m² and the maximum current efficiency reaches 3.12 cd/A.The experimental results show that the proper amount of molybdenum trioxide helps to improve the quality of the perovskite film,enhance the hole-transporting ability of the composite hole-transporting layer,improving the device photoelectric performance.At last,Graphene oxide?GO?is added to PEDOT:PSS to form a composite hole transport layer,and the effect of this method on perovskite crystals,film quality and performance of PeLEDs devices is studied.The optimal volume ratio of PEODT:PSS and GO is 1:0.3,and the maximum device luminence and current efficiency are3302.66 cd/m² and 1.91 cd/A,respectively.The experimental results show that the proper amount of GO helps to improve the quality of the perovskite thin film,enhance hole injection capability,and improve the device's electrical performance.