| Recently,organic light-emitting diodes(OLEDs)have become a research hotspot,due to their unique advantages such as small volume,lightweight,wide energy saving,environmental protection and simple preparation process.Iridium complexes synthesized with pyridazine structures can be expected to have good photoelectric properties.It is found that pyridazines complexes are easy to synthesize tri-cyclometalated iridium complexes,mainly due to the o-nitrogen atoms without hydrogen atoms in pyridazines structures,which enhances the binding capacity of pyridazines ligands with the metal iridium.It is also found that the complexes containing ether bonds are easily hydrolyzed,and the factors affecting the degree of hydrolysis and the effect of hydrolysis on the photoelectric properties of iridium complexes are further discussed.In order to continue the research of iridium pyridazine complexes in the research group,five iridium complexes were synthesized in this thesis.In addition,pyridazines iridium complexes with large steric discene structures were designed and synthesized to reduce the concentration quenching of iridium complexes,and the effect of tripterene structure on the photoelectric properties of the complex was studied.The first part of the thesis:The main ligands with different structures were prepared,1-(2,6-dimethylphenoxyl)-4-phenylbenzopyridazine(HL1),1-(2,6-diisopropyl-phenoxyl)-4-phenylbenzopyridazine(HL2)and1-(2,6-dimethylphenoxyl)-4-(4-phenyl-phenoxyl)benzopyridazine(HL3).Five iridium complexes(Ir(L1?)2S2CNEt2(1)?Ir(L2?)(L2)S2CNEt2(2)?Ir(L3)2S2CNEt2(3)?Ir(L3?)(L3)S2CNEt2(4)?Ir(L3?)2S2CNEt2(5)(L1?=L2?=4-phenylbenzopyridazine-1-hydroxyl?L3?=4-(4-phenoxyphenyl)benzopyridazine-1-hydroxyl))were synthesized by treatment of these main ligands with dithiolate ligands.Different ligands have great influence on hydrolysis.The introduction of steric hindrance groups and electron-pulling groups reduce the degree of hydrolysis.The photophysical and electrochemical data of five iridium complexes were analyzed.Their emission wavelength in dichloromethane is in the range of 590nm?610nm,which is orange-red emission.The luminous life is 1.55?s?3.59?s,and the quantum efficiency ranges from 5.5%to 22.8%.5%weightlessness temperature(Td)is 259??320?.Moreover,the degree of hydrolysis is enhanced,the luminous life is shortened and the quantum efficiency is reduced.The complexes 1,4 and 5 were doped into the main material to prepare the electroluminescent devices,and the optimal doping concentration is 2wt%,15wt%and 5wt%,respectively.The starting voltages of the device D1,D4 and D5 are 3.9V,4.2V and 4.3V,respectively.Since the hydrogen atom in the ether bond of the product belongs to an electron-withdrawing group,the resulting???*transition is a forbidden transition,and the intersystem crossing process is strengthened,which will directly lead to a decrease in luminous intensity and luminous efficiency.Therefore,the light-emitting performance of the device will decrease as the increase of hydrolysis degree.The maximum brightness of complexes D1,D4 and D5 is 1791cd/m2,694cd/m2and 498cd/m2,respectively.The maximum current density is 0.91cd/A,1.89cd/A and 0.61cd/A,respectively.And the maximum external quantum efficiency is 0.65%,1.01%and 0.42%,respectively.The second part of the thesis:The iridium complex Ir(tfmpipt)3 containing sterically hindered triptycene structure and the reference complex Ir(tfmp)3 were successfully prepared and separated by the reaction of(9S,10S)-12,15-bis-(3-(trifluoromethyl)-phenyl)-9,10-dihydro-9,10-[4,5]-epipyridazin oanthracene(HL4)and 1,4-bis(3-(trifluoro-methyl)-phenyl)phthalazine(HL5)with Ir Cl3·3H2O,respectively(tfmpipt=L4,tfmp=L5).The two iridium complexes were characterized by 1H NMR,13C NMR,19F NMR and single-crystal X-ray diffraction.The photophysical and electrochemical data of the complexes Ir(tfmp)3 and Ir(tfmpipt)3 were analyzed.By comparing the properties of the complex Ir(tfmpipt)3and the complex Ir(tfmp)3,the complex Ir(tfmpipt)3containing rigid tridiene structure has a large steric resistance surface,which can isolate the luminescent core from the outside and prevent phosphorous quenching,and has little effects on the emission wavelength.Meanwhile,the complex Ir(tfmpipt)3 has shorter fluorescence life,higher radiation transition rate and better thermal stability.Then,the optimal doping concentrations of the complexes Ir(tfmp)3 and Ir(tfmpipt)3 were 1 wt%and 10 wt%,respectively,and the non-doped device of the complex Ir(tfmpipt)3was also prepared,and their electroluminescent properties was studied.The initial voltage of the device is 3.3V,2.9V,2.6V.The maximum brightness is 6132cd/m2,25680 cd/m2and 2457cd/m2,the maximum external quantum efficiency is 21.1%,19%and 5%,and the maximum current efficiency is 35.1cd/A,55.56cd/A and 13.26cd/A,respectively.By comparing the Roll-off values of the two complexes,the Roff-off value of the complex Ir(tfmpipt)3 is smaller,indicating that the luminous efficiency of the iridium complex containing the triptycene structure is more stable.Therefore,the introduction of rigid non-conjugated triptycene structure can improve the luminance,reduce the initial voltage and make the properties of the device more stable. |
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