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 0.476μs and the quantum efficiency is0.027.As to[Ir（dpbq）₂（L¹）]:the maximum emission peak at 772 nm,the lifetime of 0.111μs 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 0.146μs,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 0.110μs 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%.