Study On The Electrophosphorescence Properties Of Several Copper (l) Complexes

In passed decades, major breakthroughs have led to significant improvements inthe performance of organic light-emitting devices (OLEDs) due to the use ofelectrophosphorescence metal complexes, while new materials with better propertiesare still needed to fully realize the advantages that organic and polymer LEDtechnology can potentially offer and to overcome the disadvantages of currentmaterials such as high costs and environment pollution. Current phosphorescent dyesare expensive because of the requirement of noble metals to achieve highphosphorescent efficiency. Therefore it is worthwhile to develop some alternativescontaining cheap metals to circumvent these difficulties. In chapter three, we used one highly phosphorescent tetranuclear coper(I)cluster---Cu4 (C≡Cph)4 L 2 [L=1,8-bis(diphenylphosphino)-3,6-dioxaoctane] , whichdisplayed intense emission at 520nm with a quantum yield of 0.42 indichloromethane. We reported the results of devices using a blend film of Cu4 andhole transport polymer PVK as the emitting layer. The structure of the devices is - 59 -吉林大学硕士学位论文 中英文摘要ITO/Cu4:PVK /TAZ/Mg:Ag/Ag and ITO/Cu4: PVK/TAZ/Mg/Al and it can realize thepure emission of triplet Cu4 at 516nm. The research focused on energy transfermechanism especially on EL process and the influence of oxygen on theluminescence of Cu4. In chapter four, a simple mixed-ligand Cu (I) 2,9-dimethyl-1,10-phenanthrolinecomplex [Cu(dmp)(POP)]BF4 [POP=Bis[(2-diphenylphosphino)phenyl]ether] wasused to fabricate OLEDs with different structures. The maximum luminance of thephosphorescent devices reached 1400 cd/m2 and the highest luminance efficiencyexceeded 1 cd/A for single layer device. Introduction of a hole block layer PBD andan electron injecting layer of tris(8-hydroxyquinoline) aluminum (III) (Alq3) causedan increase of luminescence efficiency up to 1.8 cd/A. Efficient carrier transportingability for Cu-complex-dopant system is very important for device performance. The40 wt.% PVK-PBD based devices were more suitable than PVK-based devices likelydue to PBD's electron transport and hole block ability. The EL spectra show thecharacteristic spectra of [Cu(phen)(POP)]PF6 with a peak at 576 nm and CIE of (0.44,0.48). Particularly, the highest efficiency was always achieved near the highestbrightness voltage instead of near the turn-on voltage where normal devices usuallyhave their highest efficiency.