Study On The Synthesis And Luminescence Properties Of Iridium Complexes Based On Naphthalenyl Imidazo[2,1-b]thiarole Derivatives As Primary Ligands

Organic electro-phosphorescent devices have a wide range of applications in display devices,solid-state lighting and other fields.In principle,organic electro-phosphorescent materials have the advantage that the triplet exciton energy can be utilized,to induce the internal quantum efficiency of materials reaching 100%and improving the luminous efficiency of corresponding devices greatly.In order to make full use of this advantage to obtain high-efficiency devices,the development of novel phosphorescent materials has attracted researchers'great interest.Among them,iridium(?)complexes with high quantum efficiency,short excited state lifetime and multiple luminescence colors have become the most potential commercial materials.In this papers,10 iridium(?)complexes with naphthyl-imidazo[2,1-b]thiazole derivatives as novel primary ligands were synthesized.Their structures,photophysical properties,electrochemical properties and their photoluminescence properties were characterized by nuclear magnetic resonance(NMR)spectra,mass spectra(MS),Fourier transform infrared spectroscopy(FT-IR),photoluminescence(PL)spectra and cyclic voltammetry(CV)method.This dissertation describes major conclusions as below:1.Four novel iridium complexes based on 3-methyl-6-(naphthalen-2-yl)-imidazo[2,1-b]thiazole(mn2mt)as primary ligand and pic,3-IQA,2-QA,and hppy as auxiliary ligands were synthesized.Studies have showed that the emission peak of the complexes is from 562 to 609 nm,and the emission color ranges from yellow light to red light.The internal quantum yields range from 9.7%to 55.5%,and the photonic quantum yield of(mn2mt)₂Ir(hppy)is the highest.The LED based on(mn2mt)₂Ir(hppy)obtained a maximum luminescence efficiency of 0.7 lm/W,and the color purity is over 19%.2.In order to investigate the influence of the introduction of electron-with drawing groups on the luminescence properties of materials,trifluoromethyl was introduced into the nitrogen end of 3-methyl-6-(naphthalen-2-yl)-imidazo[2,1-b]thiazole(mn2mt).Two iridium complexes based on 6-(naphth-2-yl)-3-(trifluor omethyl)imidazo[2,1-b]thiazole(n2tfmt)as the primary ligand,3-IQA and 2-QA as auxiliary ligands were prepared.The introduction of CF₃reduces the tri plet energy level of the complexes and increases the energy level gap.The cor responding complexes emit faint orange light at 585 and 593 nm with lightly blue-shift.3.To further investigate the effects of different naphthalene-linked positions on the luminescence properties of materials,we synthesized four iridium complexes using 3-methyl-6-(naphthalene-1-yl)imidazo[2,1-b]thiazole(mn1mt)as the primary ligand and pic,3-IQA,2-QA,and hppy as the auxiliary ligands.The experimental results show that the emission wavelength of the complexes can be adjusted to557?619 nm with lightly blue-shift by changing the position of the naphthalene coupling,and the emission from yellow and orange light to red light can be realized.By introducing different auxiliary ligands,the internal quantum yields of the complexes range from 7.2%to 46.6%,among which(mn1mt)₂Ir(hppy)is the highest.Overall,10 iridium complexes based on naphthalonyl imidazo[2,1-b]thiarole derivatives primary ligands could emit red,orange,and yellow light with difference auxiliary ligands.Some of the complexes,such as(mn2mt)₂Ir(hppy)and(mn1mt)₂Ir(hppy)show high internal quantum efficiencies,which have the potential to be applied in the field of OLEDs.The introduction of trifluoromethyl to the nitrogen end of the primary ligand would result in a small blue shift in the luminescent color of the complex,but the internal quantum yield would be significantly reduced.When using the same auxiliary ligands,the internal quantum yields of the iridium complexes with 3-methyl-6-(naphthalene-1-yl)imidazolium[2,1-b]thiazole as the primary ligand are slightly lower than that with 3-methyl-6-(naphthalene-2-yl)imidazolium[2,1-b]thiazole as the primary ligands.