Synthesis And Properties Of D-A Cyclometalated Iridium Complex Near Infrared Luminescent Materials With Benzotriazole As Receptors

In recent years,organic near infrared light-emitting diodes（NIR-OLEDs）have become more and more concerned by researchers because of their wide spread use in communications,energy,sensing and biomimetic fields.As a core of NIR-OLEDs,organic near infrared luminescent materials have become one of the most dynamic and vital research areas in today’s new materials.In this paper,a new type of D-A ring metal iridium complex near infrared luminescent material was designed and synthesized by using the electron-rich triphenylamine as D unit,lack of electron benzotriazole and isoquinoline as A unit.The emission spectra of the complexes were extended to the near infrared region by the charge transfer（MLCT）between the metal and the ligand in the molecule,and a good research effect was obtained.The molecular structures of the iridium complexes were characterized by MALDI-TOF MS and ¹H NMR.The structures were characterized by UV-vis,PL,CV,AFM and TGA were used to study their electrochemical properties,photophysics,surface morphology and thermal stability.Finally,the electroluminescent performance test was carried out.The NIR-OLEDs were prepared by using the host-guest doping system as the luminescent layer and the cyclometalated iridium complex as the object.The main research results are listed below:1.We designed and synthesized three kinds of D-A type cyclometalated iridium complexs of（TPA-BTz-Iq）2Irpic,（t Bu PA-BTz-Iq）2Irpic and（FTPA-BTz-Iq）2 Irpic,in which TPA-BTz-Iq,t Bu TPA-BTz-Iq and FTPA-BTz-Iq as the D-A ligands,and picolinic acid as auxiliary ligands,respectively.Using these cyclometalated iridium complexs as dopant in NIR-OLEDs,they displayed the similar NIR EL emission peaked at 712 nm with a shoulder at 780 nm.The（tBu PA-BTz-Iq）2Irpic based on OLEDs achieved the EQE_max of 0.66%.While the complexes（TPA-BTz-Iq）2Irpic and（FTPA-BTz-Iq）2Irpic achieved the EQE_max of 0.29 % and 0.24%,respectively.Through the further optimization of the device structure,the luminous efficiency of the complex（FTPA-BTz-Iq）2Irpic was doubled,EQE_max reached 0.57%.2.Designed and synthesized two kinds of cyclometalated iridium complexs of（CH₃O TPA-BTz-Iq）2Ir（pic-OXD）,（CH₃OTPA-BTz-Iq）2Ir（pic-FL）,in which oxadiazole picolinic acid derivatives（pic-OXD）and fluorenylpyridinecarboxylic acid derivatives（pic-FL）as auxiliary ligands,CH₃OTPA-BTz-Iq as the main ligand.The near infrared emission of the cyclometalated iridium complexs was achieved.A near infrared device with NIR EL emission peaked at 714 nm,EQE_max of 1.0% was obtained by using complexes（CH₃OTPA-BTz-Iq）2Ir（pic-OXD）as dopant.