Synthesis And Optoelectronic Properties Of Novel Iridium Complexes With Near-infrared Phosphorescence

Iridium complexes are highlighted due to their relatively high quantum efficiency and significantly reduced efficiency roll-off with the unique octahedral configuration and?s-graded?0?1.0?s?lifetime for suppressing the molecular aggregation and the triplet excitons'quenching.Moreover,In order to realize the near-infrared?NIR?luminescence of the iridium complexes,the usage of both highly conjugated Hiqbt or Hdpbq as the main ligand and bromo-or vinyl-functionalized ancillary ligand can be dependent for the heteroleptic one.Especially,the incorporation of bromo-or vinyl-functionalized group into the heteroleptic iridium complex gives a future possibility to covalently graft into organic polymer for new metallopolymeric material with NIR luminescence.In this thesis,four new iridium complexes with bromo-or vinyl-functionalized group were synthesized,and their optoelectronic property were investigated upon the structural characterization.The main contents are as follows:?1?Using Hiqbt?1-?benzo[b]thiophen-2-yl?isoquinoline?as the first ligand and Brppy?2-?4-bromophenyl?pyridine?as the second ligand,the heteroleptic complex[Ir?iqbt?₂?Brppy?]was obtained.Further using Hdpbq?2,3-diphenylbenzo[g]-quinoxaline?as the first ligand and bromo-functionalized ligand HL¹??E?-4-bromo-2-methoxy-6-??phenylimino?methyl?phenol?as a second ligand,the heteroleptic complex[Ir?dpbq?₂?L¹?]was prepared.Based on the structural characterization by proton nuclear magnetic resonance spectra?¹H NMR?,fourier transform infrared spectroscopy?FT-IR?and elemental analysis?EA?,their photophysical properties were studied.For complex[Ir?iqbt?₂?Brppy?]:the maximum emission peak is located at 692 nm,the lifetime is 0.476?s and the quantum efficiency is0.027.As to[Ir?dpbq?₂?L¹?]:the maximum emission peak at 772 nm,the lifetime of 0.111?s and the quantum yield of 0.007 are exhibited.?2?Using Hdpbq as the main ligand and HL²??E?-4-bromo-2-??phenylimino?methyl?phenol?as auxiliary ligand,the heteroleptic complex[Ir?dpbq?₂?L²?]was obtained.In contrast,just with the vinyl-functionalized 4-VB-HPLP??E?-4-?4-vinylbenzene?-2-??phenylimino?methyl?phenol?as the ancillary ligand for replacement,the vinyl-modified complex[Ir?dpbq?₂?4-VB-PLP?]was obtained.Upon the structural characterization and the photophysical investigation,the complex[Ir?dpbq?₂?L²?]exhibits the maximum emission peak at 776 nm,the lifetime of 0.146?s,and the quantum yield of 0.012,respectively.As for complex[Ir?dpbq?₂?4-VB-PLP?]with vinyl-modification,the maximum emission peak at 797nm,the lifetime of 0.110?s and the quantum yield of 0.005 are displayed.?3?In consideration of the realization of NIR electroluminescent device,the iridium complex[Ir?iqbt?₂?Brppy?]was doped into the host of PVK and OXD-7,NIR polymer light-emitting device?PLED?I with the configuration of ITO/PEDOT:PSS?40 nm?/PVK?65%?:OXD-7?30%?:[Ir?iqbt?₂?Brppy?]?5%,30 mg/mL??120 nm?/LiF?1 nm?/Al?100 nm?and the optimized NIR-PLED II configurated with ITO/PEDOT:PSS?40 nm?/PVK?65%?:OXD-7?30%?:[Ir?iqbt?₂?Brppy?]?5%,30 mg/mL??120 nm?/TmPyPB?15 nm?/LiF?1 nm?/Al?100 nm?were fabricated,respectively.Their electroluminescent property showed that besides the similar emissive location at 692 nm,the optimized NIR-PLED II with TmPyPB-assisited electron-promoting can get relatively higher maximum external quantum efficiency(EQE_max)of 1.34%.