Electroluminescent Device Based On 3D Perovskite Materials

A kind of perovskite material based on CH₃NH₃PbX3?X represents halogen elements?has drawn extensive attention around in recent years.The most common perovskite materials?CH₃NH₃PbI3?CH₃NH₃PbBr3?CH₃NH₃PbCl3?used in most of studies were obtained by substituting the halogen element X.The band gap is 1.5 eV,2.3 eV and 3.1 eV,respectively.The absorption coefficient of CH₃NH₃PbI3 is as high as 105,and,the photoluminescence quantum efficiency?PLQE?of this kind of perovskite is above 70%.Furthermore,its low cost and easy solution preparation makes it as ideal candidate for large-scale roll-to-roll production.These advantages have made perovskite materials widely used in thin film solar cells and electroluminescent devices in recent years.By introducing hole transport layer Poly?3,4-ethylenedioxythiophene?/Poly?styrenesulfonate??PEDOT:PSS?and the nickel oxide?NiO?,electron transport layer zinc oxide?ZnO?and the blocking layer polymethyl methacrylate?PMMA?,we have designed and prepared three kind of high brightness green light-emitting devices.A PIN structure plane heterojunction was prepared and bromine-based perovskite materials?CH₃NH₃PbBr3?was used as the emissive layer in the in the thesis.The structures of LEDs are as follows:A.ITO/PEDOT:PSS/CH₃NH₃PbBr3/PMMA?0,1,2,3,4 Layer?/ZnO/InB.ITO/PEDOT:PSS/CH₃NH₃PbBr3/PMMA/InC.ITO/NiO/PEDOT:PSS/CH₃NH₃PbBr3/PMMA/ZnO/InAnd the results indicate that:?1?For the device PEDOT:PSS as the hole transport layer and ZnO as the electron transport layer,PMMA coating on the perovskite can greatly reduce the roughness of the film,and leakage of the device,thus improving the luminous efficiency of the device.?2?As shown in the structure of the device B,if the electron transport layer ZnO was removed,the emission luminance of the device was decreased dramatically.This indicates that the ZnO electron transport layer can improve the device performance and enhance the device luminous efficiency.?3?If NiO and PEDOT:PSS hybrid bilayer was used together as the hole transport layer,as shown in the structure of device C,we found that although NiO can increase the brightness of the device,the use of NiO layer leads to the increase of device series resistance,resulting in the rise of temperature and thus attenuation of the luminance,finally,affecting the device's luminous performance when the device is operated under forward bias.