Synthesis And Properties Research Of Phosphoryl-based Iridium Complexes And Electron-transporting Materials

In recent years,considerable attention has been attached to organic light emitting diodes(OLEDs)due to their successful applications in full-color flat-panel display and solid-state lighting.As an important research hotspot in organic electronics,the development of novel materials for OLEDs is in full swing.In this paper,novel and efficient blue iridium complexes and electron-transporting materials were designed and synthesized by ingeniously introducing phosphoryl moiety into the structures.These materials were fabricated for OLEDs,which exhibited excellent performances due to their high electron mobility.This strategy is of great value for the developing highly efficient materials for OLEDs.1.Two novel bis-cyclometalated Ir(III)complexes containing phenyl(pyridin-2-yl)phosphinate(ppp)or dipyridinylphosphinate(dpp)as the ancillary ligands were designed and synthesized.Both the two iridium complexes exhibited short lifetime,excellent thermal ability and high electron mobility.Then they was used as guest materials for fabricating blue phosphorescent OLEDs.Device PPP-1 based on(dfppy)2Ir(ppp)with the structure of ITO/MoO3(3 nm)/TAPC(50 nm)/(dfppy)2Ir(ppp)(10 wt%):26DCzPPy(15 nm)/TmPyPB(50 nm)/LiF(1 nm)/Al(100 nm)displayed good EL performances with a turn-on voltage of 2.9 V,a peak current efficiency(?c,max)of 52.49 cd/A,a maximum external quantum efficiency(EQEmax)of 25.2%,a peak power efficiency(?p,max)of 51.50 lm/W with low efficiency roll-off.The(dfppy)2Ir(dpp)-based device DPP-2 with the configuration of ITO/MoO3(3 nm)/TAPC(50 nm)/TcTa(5 nm)/(dfppy)2Ir(dpp)(10%):26DCzPPy(15 nm)/TmPyPB(50 nm)/LiF(1 nm)/Al(100 nm)exhibited excellent EL performances of a ?c,max of 58.78 cd/A,a EQEmax of 28.3%,a ?p,max of 52.74 lm/W with small efficiency roll-off ratios.The prominent performances of(dfppy)2Ir(ppp)and(dfppy)2Ir(dpp)-based devices maybe due to the suitable HOMO/LUMO levels and high electron mobility,which are helpful in balancing the injection,transport and distribution of carriers.The results demonstrated that these iridium complexes with pyridinylphosphinate ancillary ligands are potential blue phosphorescent materials for facilitating the commercial applications of OLEDs.2.The structure of 2-(2,4-difluorophenyl)pyridine was modified by changing benzene ring into pyridine heterocycle or introducing the strong electron-withdrawing cyano group into the benzene ring for lowering the HOMO level and making a hypsochromic shift of the above two irdium complexes.In light of this,four novel deep blue iridium complexes(dfpypy)2Ir(ppp),(dfpypy)2Ir(dpp),FCNIr(ppp),FCNIr(dpp)were designed and synthesized,which shown the emission maxima at 458,453,459 and 458 nm,respectively.Then(dfpypy)2Ir(ppp)and FCNIr(ppp)were employed as guest materials for fabricating OLEDs with the configuration of ITO/MoO3(3 nm)/TAPC(50 nm)/(dfpypy)2Ir(ppp)or FCNIr(ppp)(10%):TcTa(5 nm)/(dfpypy)2Ir(ppp)or FCNIr(ppp)(10%):26DCzPPy(15 nm)/TmPyPB(50 nm)/LiF(1 nm)/Al(100 nm)?The(dfpypy)2Ir(ppp)-based device exhibited a ?c,max of 24.51 cd/A,a EQEmax= of 12.4%,a ?p,max of 21.99 lm/W,while device based on FCNIr(ppp)shown the performances of a ?c,max of 16.27 cd/A,a EQEmax of 8.0,a ?p,max of 13.10 lm/W.3.A novel method for the synthesis ofphosphorylated heterocycles was disclosed:versatile intermediate propargylamine serving as a new type of radical acceptors incorporating with P-radical via a photocatalytic strategy.This reaction proceeds through a cascade phosphinoylation/cyclization/oxidation/aromatization pathway using readily available starting materials under mild conditions of light with excellent atom economy,catalyzed by AgOAc or fac-Ir(ppy)3.One of the phosphorylated quinolines was selected as an example as an electron-transporting material for fabricating phosphorescence organic light-emitting diodes displaying excellent electroluminescence performances with the maximum luminance close to 40000 cd/m2,a ?c,max of 83.53 cd/A,a EQEmax of 21.9%and a ?p,max of 67.27 lm/W as well as negligible efficiency roll-off ratios.