Synthesis And Photoelectric Properties Of Polycyclic Aromatic Hydrocarbon Substituted Carbazole-containing Star-shaped Dinuclear Cyclometated Iridium/Platinum Complexes

The work reviews the development and research status of the white organicelectroluminescent materials and white organic light-emitting diodes. To resolve aseries of problems, such as few varieties of materials, poor chromaticity stability andpoor performance in device, we designed and synthesized two series of polycyclicaromatic hydrocarbon substituted carbazole-containing star-shaped dinuclearcyclometalated iridium/platinum complexes. Their molecular structures werecharacterized by1H NMR,13C NMR, MALDI-TOF MS and elemental analysis. Theirphotophysical, thermal, electrochemical and electroluminescent properties wereinvestigated.The key results of this paper are listed below:1. Three naphthalene/anthracene carbazole-containing star-shaped dinuclear cycl-ometalated iridium complexes electroluminescent phosphorescent material weredesigned and synthesized. These iridium complexes had good thermal stabilityproperties, and the introduction of blue fluorescent groups had minor changes forthe photoluminescence(PL) spectra. Using these iridium complexes as the guest inthe host matrix PVK and PBD, the single-emissive-layer (SEL)-based PLEDsexhibited nearly white light emitting. The electroluminescence spectrum hadminor changes with increasing applied voltages. Wherein the CIE coordinateslocated at (0.27,0.30),(0.28,0.32) and (0.27,0.32), respectively, a pure whitelight emission were obtained, under the applied voltage of14V at2%dopingconcentration.2. Two star binuclear cyclometalated platinum complexes derived from a platinum(II)(2-(4’,6’-difluorophenyl)pyridinato-N,C2’)(picolinate) unit containing carbazoleor carbazole naphthalene functionalized unit pending into the picolinate, and a starbinuclear cyclometalated platinum complexes derived from a platinum(II)(2-(4’,6’-difluorophenyl)pyridinato-N,C2’)(2,4-pentanedionato-O,O) unit containingcarbazole uint pending into the2-(4’,6’-difluorophenyl)pyridine were designedand synthesized. The PL spectra of the former two platinum complexes located atblue region in dilute DCM, and the emission was significantly inhibited in thesolid film due to the introducting of carbazole or carbazol naphthalene uint. Whilethe last platinum complexes exhibited red shift in dilute DCM, and was mainlycharacterized by aggregation in the solid film state. Using these platinum complexes as the guest in the host matrix PVK and PBD, the SEL-based PLEDsobtained ideal white light emitting. The complexes D(FPtpic)TriPhC6D(dHCz)and D(FPtacac)TriPhC6D(dHCz) presented white emission at1%,2%and4%doping concentration, while the complexes D(FPtpic)TriPhC6D(dnaCz) presentedwhite emission at2%,4%and8%doping concentration. Wherein D(FPtpic)-TriPhC6D(dHCz) obtained pure white emission under the voltage of15V at1%doping concentration, CIE coordinates at (0.32,0.33).Hence, the star-shaped dinuclear cyclometalated iridium(III)/platinum(II)complexes are a novel class of white organic electroluminescent materials. Thisresearch work has an important significance on the development of singlewhite-emitting molecular and the application for the environmentally friendly andhigh efficiency WPLEDs.