Synthesis Of Cyclometalated Iridium Complexes And Studies On Their Properties In Electrophosphorescent Devices

The electroluminscent mechanism and research status oforganic/polymeric electrophosphorescent materials and devices arereviewed in this dissertation. Bis-cyclometalated iridiumcomplexes using as electrophosphorescent materials were studiedin order to solve current problems of electrophosphorescentmaterials and devices. Two series of bis-cyclometalated iridiumcomplexes, including six complexes, were designed andsynthesized, and their molecular structures were characterized. Thepolymeric electrophosphoresent devices were fabricated with thesecomplexes as guest and polymers such aspoly(vinylcarbazole)(PVK) or poly(9,9-dioctylfluorene) (PFO) ashost. Five ligands of derivatives of 1, 3, 4-oxadiazole weresynthesized by a series of reactions such as esterification with aseries of aryl acids, hydrazinolysis, diaroylhydrazide anddehydration. Another a type of ligand of the derivative of2-phenylpyridine with triarylamine moiety was synthesized byGomberg-Bachmann reaction with pyridine and 4-nitroaniline,Pd-C reduction, Ullmann reaction at the same time. The obtainedligands were reacted with IrCl3 3H2O to give six chloride-bridgeddimmers respectively. At last these dimmers were converted tobis-cyclometalated iridium complexes respectively by achloride-bridged replaced reaction with acetylacetone. Theirmolecular structures were characterized by 1HNMR, elementanalysis and GC-MS. The results of UV spectra showed that all ofthese bis-cyclometalated complexes had intense absorption peaks吴忠联:环金属铱配合物的合成及其电磷光器件的性能研究from metal-to-ligand charge transfer(MLCT) transitions, whichindicates these Ir-complexes should be used as two serious of novelelectrophosphorescent materials. The polymeric electrophosphorescent devices were fabricatedwith these complexes as guest and PVK or PFO as host. Thehighest external quantum efficiencies(QEext) of 2.77% ph/el and10.4% ph/el were demonstrated respectively for red and greenpolymeric electrophosphorescent devices. Electroluminscentefficiency of the green electrophosphorescent device was consistentwith international level. These researches indicated thatcyclometalated ligands, which are attached to functional groupswith carrier transporting properties and tert-butyl units, werehelpful to improve electrophosphorescent properties of theircorresponding iridium complexes. The iridium complex withtert-butyl and triarylamine moiety had a betterelectrophosphorescent properties. The studies of red polymericelectrophosphoresent devices demonstrated the external quantumefficiency of the device using PFO as host is better than using PVKas host . The hosts in the electrophosphorescent devices play amore important role in electrophosphorescent properties. In a word, this research laid a better foundation for furtherstudy of tricolor electrophosphorescent materials and their devices.It should be more useful to acquire efficient electrophosphorescentmaterials and devices at the same time.