Study On Transparent Perovskite Electroluminescent Devices Based On Multilayer Structure Transparent Electrodes

Metal halide perovskite semiconductor materials have some advantages such as high fluorescence quantum efficiency,high carrier mobility,and high color purity.Using thinner light-emitting layers can achieve higher device performance,which allows us to predict their potential application prospects in the future transparent display field.One of the key issues in achieving efficient transparent perovskite light-emitting devices（T-PeLEDs）is the selection of transparent top electrodes.It not only requires high transmittance and low surface resistance,but also requires energy levels that match the active layer for more efficient carrier injection.In addition,due to the high temperature intolerance of luminescent materials,transparent top electrodes are also required to have a low-temperature deposition process.These requirements have increased the difficulty of developing new transparent top electrode materials.So far,there are not many studies on T-PeLED,and the brightness and efficiency also need to be improved.Dielectric/metal/dielectric（DMD）transparent electrodes not only have the same photoelectric performance as traditional ITO electrodes,but also can effectively regulate the electrode work function through the selection of dielectric layer materials,thereby achieving better energy level matching with the active layer,and achieving effective injection and recombination of current carriers.At the same time,the DMD transparent electrode has a low-temperature preparation process,which can be better compatible with the active layer processing process.In view of this,this topic takes T-PeLED as the research topic,mainly through the design and preparation of transparent electrodes suitable for T-PeLED,using transparent electrodes and optimized perovskite thin films to achieve efficient and high brightness T-PeLED.The research results obtained are as follows:1.The effects of the morphology and thickness of Ag thin films on the sheet resistance and transmittance of DMD electrodes were studied by studying the growth kinetics of metallic Ag on organic dielectric layers.Considering the electrical and optical properties of DMD electrodes,the figure of merit（Fo M）of the electrode has a maximum value when the thickness of Ag is 18 nm.The electrode structure of TPBi（15 nm）/Bphen（30 nm）/Cs₂CO₃（1 nm）/Ag（18 nm）/MoO₃（35 nm）was determined by adjusting the type and thickness of the dielectric layer through a combination of simulation and experimental verification.2.Using ITO bottom electrode and DMD top electrode,combined with previous optimization of perovskite luminous layer,high efficiency and high brightness T-PeLED was prepared.The effect of Ag thickness on the injection performance of single carrier devices was investigated.Finally,the properties of T-PeLED devices are as follows:the maximum luminous brightness on one side of the ITO reaches 21100 cd/m²,the maximum external quantum efficiency（EQE）is 5.28%;the maximum luminous brightness on one side of the DMD electrode is 7940 cd/m²,the maximum EQE is1.72%,the total brightness of the device reaches 29040 cd/m²,and the total EQE reaches 7%,the light output ratio of both electrodes is 2.66:1.Compared to the previously reported T-PeLEDs,they have improved in brightness and EQE.3.A MoO₃/Ag/MoO₃（MAM）electrode,which can replace ITO as the transparent bottom electrode,was designed and prepared.The influence of the thickness of MoO₃on the photoelectric performance of the electrode was explored through simulation and experiment.Compared with ITO electrode,MAM has a flatter surface topography.Using this MAM electrode,T-PeLED with DMD electrodes on both sides of the device was prepared.The maximum luminance at the bottom electrode reached 8320 cd/m²and the maximum EQE reached 2.92%.The maximum luminance of the top electrode reaches 4110 cd/m² and the maximum EQE reaches 1.30%.The total brightness of the device reached 12430 cd/m²,the total EQE reached 4.22%,and the light output ratio of both sides was 2:1.It provides the direction for further study of T-PeLED with bilateral DMD electrodes.