Synthesis And Photoelectric Properties Of Indolecarbazole-Quinoxaline Derivative

Organic light-emitting diodes(OLEDs)are widely used in full-color flat panel displays and other fields because of their sensitive response and good vibration resistance.An asymmetric novel luminescent with dihydroindolyl carbazole as the donor and quinoxaline compound as the acceptor was designed and synthesized,which made the molecule twist larger by changing the alkyl chain,and enhanced the rigidity and conjugation characteristics of the acceptor part of the molecule to improve the hole transport capacity.Firstly,five compounds I-5a-5e with diphenylquinoxaline as the acceptor were designed and synthesized,and the two benzene rings on the parent nucleus of the acceptor quinoxaline could rotate freely,which was conducive to reducing the loss caused by the accumulation of π-π.The orbital distribution of compounds is simulated by theoretical calculation,and good separation is conducive to intramolecular charge transfer(ICT).Under solvation,I-5c had a Stokes shift of up to 187 nm,and a yellowgreen OLED was prepared with I-5c as the light-emitting layer;Secondly,five compounds Ⅱ-5a～5e with benzophenazine as acceptors were designed and synthesized to convert quinoxaline into phenazine structure,and the planar structure formed was conducive to reducing energy loss.The study of photophysical properties can find that the PL emission peak is significantly redshifted at 572-638 nm,and an orange-red OLED is prepared with Ⅱ-5c as the light-emitting layer,and the EQE of the device is as high as 1.28%;Subsequently,a series of compounds Ⅲ-5a-5e with diphenylpyridinopyrazine as acceptor were designed and synthesized,pyridine as an electron-absorbing group can make the emission peak of the compound redshift,through the study of photophysical properties,it can be found that the PL peak is about 670 nm,can reach red emission,and the orange-red OLED is prepared with Ⅲ-5c as the light-emitting layer.Based on the different receptor units,the effect on the performance of the OLED device was studied,and the compound Ⅱ-5c with the acceptor benzophenazine showed the optimal performance,and the EQE was as high as 1.28%by comparing compoundsⅠ-5c,Ⅱ-5c and Ⅱ-5c.Finally,quinoxaline-like compounds Ⅳ-3a～3e with triphenylamine as donor and imidazole as acceptor were designed and synthesized,and different aryl substituents were introduced.The compounds are used to prepare electrofluorescent chromic(EFC)devices with low chromic voltages.In particular,compound Ⅳ-3e achieves color change from blue to yellow at only 0.6 V.