Synthesis And Luminescent Properties Of Rigid Cyclometalated Iridium (iii) Complexes

Heavy metal complexes, such as Ir, Os and Pt complexes, have been widely employed as luminescent materials in OLED (Organic Light-Emitting Diodes). Owing to the strong spin-orbital coupling of these heavy metal ions, both singlet and triplet excitons can be fully utilized for light emission, so the adoption of phosphorescent materials can greatly enhance the efficiencies of OLEDs. Of these materials, iridium complexes have been regarded as the most appropriate phosphorescent materials because of their relative short lifetime and high quantum efficiency. The properties of these devices, such as efficiency, brightness, and life are strongly depended on structure of the cyclometalated ligands. utilized for light emission. So the adoption of phosphorescent materials can greatly enhance the efficiencies of OLEDs. In this thesis, in order to solve the remaining problems of phosphorescent materials and devices, we designed and synthesized several new Ir complexes.Our studies mainly include two parts. One is focus on the design, synthesis of new cyclometalated iridium complexes. Followed by the study of optical and electrochemistry properties of these complexes. The other is focus on the electroluminescence performance of these devices. The following parts are included in this dissertation:1,Four new Iridium complexes with rigid cyclometalated ligands have been synthesized. Organic light emitting devices utilizing the complexes (PBQE)2Ir(acac),(EPBQ)2Ir(acac) and (EPBQ)2Ir(acac) as dopant emitter were fabricated. The device based on(EPBQ)2Ir(acac) exhibited best, which have maximum brightness of 134,055 cd/m2, maximum external quantum efficiency of 24.6%, maximum current efficiency of 72.9 cd/A, together with maximum power efficiency of 44.2 lm/W at a doping concentration of 2%. These results are excellent compared with previously reported research.2,Considering the excellent device performance based on the complexe (EPBQ)2Ir(acac), one type of efficient white organic light-emitting diode were fabricated. By utilizing the complexes (DMBA)2Ir(acac) together with an efficient blue phosphorescent iridium complex FIrpic, the device structure as:ITO/NPB(30 nm)/TCTA (20 nm)/CzSi:FIrpic(8%, x nm)/CBP:(EPBQ)2Ir(acac) (2%, ynm)/BSB(10nm)/TAZ (40nm)/LiF(1nm)/Al(100nm) was fabricated. For the EL device, maximum brightness of 34,212cd/m2, maximum external quantum efficiency of 15.6%, maximum current efficiency of 32.6 cd/A, and maximum power efficiency of 21.8 1m/W were achieved. These results are very good compared with previously reported white organic light-emitting diodes.3,Two new iridium complexes with non-cyclometalated ligands have been synthesized. Their optical and electrochemistry properties were studied carefully. The maximum emmision wavelength of complexes (BPBI)2Ir(acac) and (NPBI)2Ir(acac) is 578 nm and 580 nm. Both of them have excellent electrochemistry stabilities.