Study On Transition Metal Dichalcogenides Enhanced Photoelectric Properties Of Perovskite Light-Emitting Diodes

Organic-inorganic hybrid perovskite semiconductors have drawn great research attention due to their superior optoelectronic properties,such as high light absorption coefficient,long carrier lifetime,and diffusion length,making them ideal candidate materials in the fields of electroluminescence and photoelectric conversion.The enormous efforts of perovskite have been made to improve the performance of PeLEDs including the optimization of device structures and improvement of the perovskite film.The transition metal dichalcogenides such as MoS₂ is considered a promising material for hole injection/transport layers in PeLEDs,on account of their excellent carrier motilities and diverse energy alignment.The utilization of the local surface plasma resonance（LSPR）of MNPs can accelerate the radiative decay rate of nearby excitons through nearfield coupling,facilitating light emission and thus enhancing the performance of the PeLEDs.The paper focuses on the the optimization of the hole transport layer in PeLEDs devices by adding the Au NPs and MoS₂.（1）The influence of the MoS₂ on the performance of PeLEDs Devices are studied.The structure is ITO/PEDOT:PSS+MoS₂/CH₃NH₃PbBr₃/TPBi/LiF/Al,using the composite HTLs PEDOT:PSS+MoS₂.The device has an optimum weight ratio of 1:0.6.On the one hand,the introduction of MoS₂ in PEDOT:PSS decrease the energy barrier,and therefore facilitate the energy barrier-free hole injection.On the other hand,the existence of the MoS₂ in the PEDOT:PSS matrix could serve as an efficient charge conducting pathway to promote charge transfer and conduction.Therefore,PEDOT:PSS+MoS₂ structural alteration elongated the conductive pathway and accordingly promoted conductivity.（2）The influence of the Au NPs on the performance of PeLEDs Devices are studied.And the LSPR effect is used to improve the photoelectric performance of PeLEDs.The overlap of the absorption spectrum of Au NPs and PL of the CH₃NH₃PbBr₃ indicate the possible resonance between LSPRs excited by the Au NPs and radiated light generate in CH₃NH₃PbBr₃.The Au NPs are completely“capped”by PEDOT:PSS to prevent non-radiative energy loss of excited states produced at PEDOT:PSS/CH₃NH₃PbBr₃.The maximum luminance and current density reach 6826cd/m²and 3.57cd/A,which is 71%and 110%higher than that of the controlled PeLEDs without Au NPs,respectively.（3）The characteristics of the PeLEDs devices with the structure of ITO/Au NPs/PEDOT:PSS+MoS₂/CH₃NH₃PbBr₃/TPBi/LiF/Al are studied.The maximum luminance of 9192 cd/m² and current efficiency of 5.49 cd/A are achieved for the device with 10%Au NPs and weight ratio of 1:0.6,which represent an increase of 130%and223%compared with counterparts using PEDOT:PSS as HTLs,respectively.First,the blending of MoS₂ in the PEDOT:PSS can optimize the energy level structure to improve charge balance in the PeLEDs,and also elongate the conductive pathway to promote charge conductivity.Furthermore,the resonance between radiated light generated in CH₃NH₃PbBr₃ emitter and LSPRs excited by the Au NPs is helpful to improve the efficiency of CH₃NH₃PbBr₃ PeLEDs and promote the rate of excitons radiative decay.