Novel Iridium Complex with Carbazol-2-yl-β-diketone Derivative:Low-energy Excitation and Red Electro

A novel iridium-complex,(BPPBI)2Ir(2-TFDBC)[BPPBI=2-(biphenyl-4-yl)-1-phenyl-1H-benzo[d]imidazole,2-TFDBC=1-(9-ethyl-9H-carbazol-2-yl)-4,4,4-trifluorobutane-1,3-dione],was synthesized,and its structure and component were confirmed by 1H NMR and element analysis,respectively.UV-Vis absorption and photoluminescent(PL) spectra of (BPPBI)2Ir(2-TFDBC) in dichloromcthane were investigated.The Ir-complex exhibited a long wavelength excitation of 470 nm,i.e.,low-energy excitation.So,it is a promising candidate for phosphorescent probe and PL material.(BPPBI)2Ir(2-TFDBC)-based electroluminescent devices,ITO/MoO3(10 nm)/NPB(80 nm)/CBP:x(BPPBI)2Ir(2-TFDBC)(20 nm)/TPBi(45 nm)/LiF/AL,were fabricated,where x(％) was of 4％ or 8％ doping concentration(mass fraction); ITO=indium tin oxides; NBP=N,N'-bis-(1-naphthalenyl)-N,N'-bis-phenyl-(1,1'-biphenyl)-4,4'-diamine, CBP=4,4'-bis(N-carbazolyl)-1,1'-biphenyl, TPBi=1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene.The devices showed a red emission of 620 nm.The maximum current efficiency and brightness were 1.7 cd/A and 4063 cd/m2 for a device of 8％(mass fraction) doping level,respectively.The moderate luminous efficiency was due to the inadequate energy transfer from the host material to the guest material.