Research On High-efficiency Exciplex Light-Emitting Emitters Based On Nitrogen Heterocyclic Derivatives

In recent years,organic light-emitting devices(OLEDs)based on exciplexs have been widely studied due to their excellent performance.Exciplexs are formed between different kinds of electron donor materials and electron acceptor materials,so the synthesis of new acceptor materials and donor materials is very important.However,the reported problems of the electron acceptor materials are limited in the range of energy levels,the structure of exciplex and the backward development of red exciplex,which limit the development of exciplex.Nitrogen heterocyclic groups are widely used in electron acceptor materials because of their strong electron absorption ability and electron mobility.Therefore,it is necessary to study the novel acceptor materials and devices based on nitrogen heterocyclic groups for the construction of efficient exciplex devices.We designed and synthesized four new kinds of electron acceptor materials with nitrogen heterocyclic ring as the core,and studied the characterization of the materials and the performance of the device forming exciplex.The main research contents are as follows:(1)Two novel azocyclic receptor materials TPy-SBF and TRZ-SBF based on spirodifluorene were designed and synthesized.The theoretical calculation,electrochemical and photophysical properties of the materials were tested.These two receptor materials were used to form exciplex with three electron donor materials,13 AB,m PTBC and m PTC respectively.The OLED devices based on the exciplex was prepared.The OLED device based on 13AB: TRZ-SBF had a peak emission wavelength of 560 nm and the maximum external quantum efficiency(EQE)of 7.1%.The peak wavelength of the device based on m PTC: TPy-SBF is 524 nm,and the maximum EQE of the device is10.5%.The performance of OLED devices based on m PTBC: TPy-SBF is the best,the peak wavelength of emission is 556 nm,and the maximum EQE is 15.3%,which indicates that the research on the development of novel nitrogen heterocyclic acceptors and devices is of great significance.(2)In order to enhance the electron pulling ability of the acceptor material and realize the emission of red exciplexs,two novel azoheterocyclic electron acceptor materials 13DPy-TPy and 13DPy-TRZ were designed and synthesized.The theoretical calculation,electrochemical and photophysical properties of the materials were tested.The lowest unoccupied molecular orbital(LUMO)energy levels of 13DPy-TPy and13DPy-TRZ are-2.65 e V and-3.15 e V,respectively.The two acceptors were used to form exciplex with three electron donor materials 13 AB,m PTBC and m PTC respectively,and OLED devices based on excyl complexes as light emitting layer were prepared.Among them,OLED devices based on 13AB:13DPy-TRZ and m PTBC:13DPy-TRZ,the peak emission wavelength is 596nm;the peak wavelength of the device based on m PTC:13DPy-TRZ is 620 nm,and red light emission is realized.This work can provide guidance for the design and synthesis of red exciplexs receptor materials and the research of the device.