Design,synthesis And Properties Of New Organic Optoelectronic Materials With Nitrogen-containing Heterocycles Rings

Organic photoelectric functional materials are a class of organic materials with photoelectronic properties.Due to their high solubility,and easy modification of molecular structures,solution processing can be conveniently realized to prepare large-area devices and wearable flexible devices.In addition,by rationally modifying the structure of materials to adjust the optical and electrical properties of the materials,it is favorable for the high-performance and multi-functional applications.Organic optoelectronic materials with chiral properties have attracted much attention for their wide application in optical recognition sensors,optical communications and 3D displays.Especially using these chiral luminescent materials to prepare organic light-emitting diodes(OLEDs)can directly produce circularly polarized electroluminescence,which provides a new way for the development of low-cost,eye-protecting OLED displays.Here,we designed and synthesized a series of chiral thermally activated delayed fluorescence(TADF),phosphorescent host and chiral long afterglow materials based on nitrogen-containing heteroaromatic rings.The specific research contents are as follows:(1)A series of chiral TADF molecules were synthesized based on chiral binaphthol,cyanopyridine acceptor(A)and carbazole derivative donor(D)materials.All materials exhibit good solubility, high luminous efficiency,excellent chiral stability,and high photoluminescence asymmetry factor(g _PL).With these chiral TADF molecules,external quantum efficiency(EQE)of 12.4% and 10.6% for vacuum-deposited and solution-processed circularly polarized organic light-emitting diodes(CP-OLEDs)were achieved.The device showed the circularly polarized electroluminescence(CPEL)properties with g _EL is 3.9×10^-3.This is also the first solution-processable CP-OLED based on chiral TADF molecules.(2)Two new bipolar host materials were synthesized by connecting the strong electron-withdrawing triazine unit with a carbazole group.This type of material has a high triplet energy level,good thermal stability,and balanced carrier transport properties.Therefore, with excellent photoelectric properties,the external quantum efficiencies of 21.0%and 14.2% are obtained in blue and deep-blue phosphorescent OLEDs,respectively.In addition,the host material has also been used to prepare blue TADF OLEDs exhibit EQE over 12% and white TADF OLEDs with the EQE of 23.2%.This is the highest efficiency of white TADF OLEDs in current reports.(3)Isophthalic acid(IPA)was doped into chiral benzalkonium amine materials to prepare a eutectic material.The introduction of chiral groups induced the entire eutectic material to have chiral properties,resulting in both fluorescence and phosphorescence with chiral signals.At the same time,the presence of N atoms and C=O groups in the molecule accelerates the intersystem crossing rates,enhances the intermolecular interaction force to suppress the non-radiative transition,and finally realizes efficient yellow afterglow.Interestingly,the phenomenon of phosphorescent chiral signal amplification is achieved through the stacking of chiral molecules for the long afterglow properties.This is also the first case study on chiral eutectic long afterglow materials.