Synthesis And Photoelectrical Properties Of Phosphorescent Copper(Ⅰ) Complex With Bis-[2-(Diphenyl Phosphino)Phenyl] Ether And Triphenyl Phosphine Ligands

Phosphorescent electroluminescent materials have shown great potential in digital terminal displays and planar solid-state lighting because of high internal quantum efficiency of100%. Ir(Ⅲ) complexes have the best luminescence performances, but the reserve of which in nature becomes less and less, and more and more expensive. Consequently, looking for the alternatives of Ir(Ⅲ) complexes is imminent. In recent years, Cu(Ⅰ) complexes become a new favorite in the field of organic electroluminescence because of its low price.The P atom of phosphorus-containing organic ligands have strong electron-donating property, which can increase the d-d excited state energy level of the metal center and prevent non-radiative transition. Meanwhile, the stronger Cu-P bonds can be formed and result in blue shift in luminescence spectrum. Therefore, a series of neutral and ionic Cu(Ⅰ) metal complexes [(POP)CuI]2,[Cu(PPh3)2(pybi)]BF4,[Cu(PPh3)2(pptz)]BF4and [Cu(POP)(pptz)]BF4were synthesized by using bis-[2-(diphenylphosphino)phenyl]ether(POP), triphenyl phosphine(PPh3) as main ligands and iodine atom,2-(2-pyridyl)phenyl imidazole(pybiH) and2-(5-phenyl-1,2,3-three triazole)pyridine(pptzH) as auxiliary ligands, respectively.The molecular structures of complexes were determined by X-ray single-crystal diffractions and. the photophysical and electrochemical performance were studied by UV-vis absorption, fluorescence spectra and electrochemical method; The complexes were also applied in phosphorescent organic light-emitting diode(PhOLED) as emitting guests for studying on the electroluminescent properties. The details are as follows:1. A novel sky-blue phosphorescent material at room temperature [(POP)CuI]2was synthesized. The maximum emission peak of [(POP)CuI]2appears at475nm, which is the sky-blue light emission, and has good film forming stability. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbitals(LUMO) energy levels and the optical band gap of [(POP)CuI]2are-6.40,-3.47and2.93eV, respectively. The device with the structure of ITO/NPB(30nm)/CBP:[(POP)CuI]2(30nm,8%)/BAlq(10nm)/Alq3(nm30)/L2F(1nm)/Al(200nm) was fabricated by doping [(POP)CuI]2in CBP(CBP:4,4’-N,N’-dicaibazolebiphenyl) as light-emitting layer. Materials used for the device were NPB(NPB:N,N’-Bis(naphthalen)-N,N’-bis(phenyl)-benzidine) for hole-transport layer, BAlq(BAlq:aluminum(Ⅲ)bis(2-methyl-8-qurmolinato)-4-phenylphenolate) for hole-blocking layer, and Alq(Alq3: tris(8-hydroxyquinoline) aluminum) for electron-transport layer. The electroluminescent spectra of device was origin from [(POP)CuI]2with maximum emission peak at476nm, the maximum brightness of9539cd/m2and the maximum current efficiency of1.9cd/A.2. The ionic Cu(Ⅰ) metal complexes of [Cu(PPh3)2(pybi)]BF4,[CuCPPh3)2(pptz)]BF4and [Cu(POP)(pptz)]BF4were prepared with POP and PPh3as main ligands and pybiH and pptzH as auxiliary ligands. All the three complexes have four-coordinated ionic structures, including of one Cu(Ⅰ) ion, phosphorus-containing ligands, nitrogen-containing ligands and BF4ion. Both [Cu(POPXpptz)]BF4and [Cu(PPh3)2(pybi)]BF4have triclinic crystal system and P-1space group, while [Cu(PPh3)2(pptz)]BF4is monoclinic and P21/c with high symmetry. The complexes of Cu(PPh3)(pybi)BF4,[Cu(PPh3)2(pptz)]BF4and [Cu(POP)(pptz)]BF4all have good thermal stabilities, the temperatures of5%weight loss are210,213and269℃. The UV-Vis absorption peaks locate at the range of226-330nm. The maximum emission peaks in CH2C12solution appear at499,501and516nm, respectively. The HOMO/LUMO energy levels are-5.98A3.25,-6.01/-3.21and-5.92/-3.26eV and optical band gap are2.73,2.80and2.66eV.