Synthesis,Photoluminescence And Electroluminescence Of Novel Iridium Complexes

By incorporating hole-transporting carbazole or electron-transporting 1,3,4-oxadiazole moieties,six cylcometalated iridium complexes have been synthesized by a new method with good yield.The Ir(ppy)3 based compounds,Ir(Ll)3-Ir(L3)3,show green and yellowish green color centered at ca.503-540 nm and the Ir(piq)3 based complexes,Ir(L4)3-Ir(L6)3,display red emission located at ca.611-631 nm due to the MLCT emission.The complexes Ir(Ll)3-Ir(L3)3 are potential materials for the application in OLEDs due to the strong photoluminescence intensity,high quantum efficiency and short photoluminescence decay lifetime.Five interesting bis-cyclometalated iridium complexes with tetraphenylimidodiphosphinate(tpip)as the ancillary ligand have been successfully prepared and applied in the OLEDs.The trifluoromethyl substituents at different positions on the phenyl rings of ppy in iridium complexes can affect their emission color and intensity obviously.The devices ITO/TAPC(30 nm)/Ir complexes(x wt%):SimCP2(15 nm)/TPBi(45 nm)/LiF(1 nm)/Al(100 nm)show good performances constructed by these Ir3+ complexes as the emitter.For Ir3+ complex 4 based device G4 where x = 8 wt%,a maximum luminance over 40000 cd m-2,a maximum current efficiency(?c)and power efficiency(?P)of 50.8 cd A-1 and 29.0 lm W-1 were obtained.The results suggested that all the complexes have potential applications in OLEDs.Four Htpip derivatives(R-Htpip)have been synthesized by introducing fluorine group,trifluoromethyl substituent,methoxyl group and naphthyl group.With some of them as ancillary ligands and 2-(4-(trifluoromethyl)phenyl)pyridine as the main ligand,three complexes(4-CF3-ppy)2Ir(Ftpip),(4-CF3-ppy)2Ir(MeO-tpip)and(4-CF3-ppy)2Ir(NA-tpip)were synthesized and their photoelectric properties were studied in detail.Using bipyridine modified by fluorine and trifluomethyl groups as main ligands and tpip or flpip as ancillary ligands,we synthesized four complexes:Irl((dFpypy)2Ir(tpip)),Ir2((dFpypy)2Ir(Ftpip)),Ir3((2',6,-dtFm-2,3,-bpy)2Ir(tpip))and Ir4((2',6'-dtFm-2,4'-bpy)2Ir(tpip)).With Ir3 as the emitter,the device showed encouraged results with a maximum luminance over 40000 cd m-2,a maximum ?c higher than 90 cd A-1(at 2200 cd m-2).The device also showed very low efficiency roll-off with 80 cd A-1 at 24000 cd m-2.To improve the electron mobility and the device performance,we also synthesized a new ligand 2-(trifluoromethyl)pyrimidine-pyridin and three iridium complexes(NTN)2Ir(acac)(NTN)2Ir(pic)and(NTN)2Ir(tpip),using Htpip,acac and pic as the ancillary ligands,respectively.All of them behaved good photoluminescence,thermal stability and are hopefully applied in OLEDs.