Research On Vaporized Perovskite Light Emitting Devices Based On Perovskite Transport Layer

Light-emitting diode(LED)is a semiconductor photoelectric device with electrooptical conversion.After decades of development,it has been widely used in the field of display lighting.In recent years,a new luminescent material-metal halide perovskite has attracted people’s attention.Metal halide perovskite has excellent photoelectric properties,such as high carrier mobility,adjustable band gap and high fluorescence quantum yield,so perovskite light emitting diodes(PeLEDs)based on metal halide have become important candidates for a new generation of light emitting diodes.However,at present,most perovskite light-emitting devices use traditional polymer materials as hole transport layers.For commercial applications,the electroluminescent properties such as brightness and efficiency of the devices still need to be further improved.Aiming at the above problems,this paper puts forward a solution of using perovskite material instead of traditional polymer material as hole transport layer.By developing vapor deposition technology,perovskite light-emitting devices with obvious improvement in brightness,current efficiency and external quantum efficiency have been successfully prepared.The specific research work is summarized as follows:(1)Aiming at the shortcomings of traditional hole transport materials,a layer of CsPbBr3 perovskite transport layer is introduced between PEDOT:PSS and perovskite luminescent layer,and the performance of vapor-deposited all-inorganic red PeLEDs is improved by using this double transport layers.Moreover,the perovskite transport layer and luminescent layer are prepared by vacuum vapor deposition through double-source co-evaporation,which not only improves the film quality but also optimizes the preparation process.The limitation of solution method is improved.At the same time,the insertion of CsPbBr3 layer avoids the direct contact between PEDOT:PSS and the film of luminescent layer,which not only effectively inhibits the fluorescence quenching caused by the acidity of PEDOT:PSS,but also improves the crystallization quality of perovskite luminescent layer.The maximum brightness and current efficiency of the light-emitting device are 1341 cd/m2 and 0.36 cd/A respectively.Compared with PEDOT:PSS single transport layer device,it is improved by 44%and 157%respectively.Then,the influence of the thickness of perovskite transport layer on the device performance is explored.Finally,the optimal electroluminescent performance is obtained when the thickness of CsPbBr3 layer is 20 nm.(2)Aiming at the problem of photon loss in the form of surface plasmon polaritons(SPPs)in perovskite light emitting devices,a periodic grating structure is prepared on the surface of perovskite thin film by laser double-beam interference,which makes the momentum and energy match between SPPs and photons in free space,thus increasing the light extraction efficiency of the device.The micro-nano structure can be applied to perovskite light-emitting devices,and the luminous efficiency of the devices can be improved on the premise of ensuring that the photoelectric characteristics of perovskite are not affectedIn this paper,the introduction of CsPbBr3 perovskite hole transport layer,the preparation of perovskite hole transport layer and luminescent layer thin films by vacuum vapor deposition.the introduction of periodic grating microstructure on the surface of perovskite thin films provide an effective scheme to improve the brightness,current efficiency and external quantum efficiency of PeLEDs.