| With the upgrading of electronics industry and the rapid development of display technology,organic light emitting diodes(OLEDs)have also been rapidly developed.Compared with liquid crystal,OLED has become a leader in display technology because of its advantages such as fast response,low cost,good flexibility,wide viewing angle,high brightness and so on.Nowadays,as a new type of display technology,the market of OLED is also growing,and the country is investing more in this field.In the nest 3~5 years,the global investment in OLED is expected to reach $30 to $50 billion.However,the development of OLED is not mature,the material that can decide the organic luminescence has not been given in the world,and the process of the device is constantly updated and perfected.Therefore,the OLED industry has a great space for development in the next few years.According to the recombination of exciton,the luminescent materials can be divided into two categories: fluorescent material and phosphorescent material.Compared with fluorescent materials,phosphorescent materials have attracted widely attention because of their excellent triplet luminescence properties,and their internal quantum efficiency can reach 100%.In the phosphorescent metal complexes,due to the short lifetime of excited state,good thermal stability,high quantum efficiency and various colors,iridium(III)complexes are very popular in OLED.A series of iridium(III)complex luminescent materials have been designed and synthesized in this thesis.In the first part,three new ?-diketone ligands and 3-dipyridine-coumarin were designed and synthesized as the second ligandand the first ligand,respectively.Then three new green light complexes Ir(L)2(1L),Ir(L)2(2L)and Ir(L)2(3L)were synthesized.The UV-Vis absorption,fluorescence emission,quantum yield,cyclic voltammetry and thermal stability of the three complexes were studied.Because the three auxiliary ligands were different,the corresponding quantum yields were obviously different.the quantum yields of Ir(L)2(1L),Ir(L)2(2L)and Ir(L)2(3L)is 4.64%,10.54% and 11.48%,respectively.To evaluate the electrochemical properties of the three complexes,the multilayer devices of three kinds of materials were fabricated by solution spin-coating method.The results show that the maximum luminance of the three materials is 4450,3646 and 9275 cd/m2,and the maximum external quantum efficiency(EQE)is 3.764,3.316 and 5.497%,respectively.In the second part,two new binuclear iridium complexes were synthesized by using3-(pyridin-2-yl)-2H-chromen-2-one and 2-(naphthalen-1-yl)benzothiazole as the first ligand,respectively,and bis-?-diketone as the second ligand.The UV-Vis absorption,fluorescence emission,quantum yield,cyclic voltammetry and thermal stability of the three complexes were studied.Compared with single ?-diketone ligand,this kind of bis-?-diketone)ligandwithmore sites,higher activity and higher luminescence efficiency is a good OLED luminescent material.In the third part,the orange light iridium complex was synthesized with 2-phenyl-6--(trifluoromethyl)benzothiazole as the first ligand and 1-(6-bromo-9-butyl-9H-carbazol-3-yl)hept-6-ene-1,3-dione as the second ligand.The quantum yield of this complex is 16.1%,which is much higher than the quantum yield of the ruthenium complex of the same dimer reported in the literature.And we have designed and synthesized a phosphorescence fluorescent hybrid material,that is,the coumarin fluorescent material of blue light is grafted onto the molecule of orange phosphorescence material,and its structure and properties were characterized and tested.This hybrid material is rare at present.It can reduce the complex flow of traditional WOLED devices simplify the device structure and avoid the phase separation phenomenon caused by doping.The UV-Vis absorption,fluorescence emission,quantum yield,cyclic voltammetry and thermal stability of the three materials were studied. |
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