Phosphorescent Properties Of New Efficient Red-emitting Iridium(Ⅲ) Complexes

Phosphorescence organic light-emitting device (PhOLED) has drawn great interest due to taking full advantage of singlet and triplet excitons to illuminate simultaneously. However, resulting from the smaller energy gap and strong interaction of electron orbits, the red phosphorescent materials generally have low luminant efficiency. Based on the lack of efficiency, we dope the host material with a series of novel high efficiency Ir(III) complexes, derivates of (pbt)2Ir(acac), and the in-depth study of the doping system comes from following four aspects:First, we analyze the device performance of different doping structure with new Ir(III) and three different host materials. Second, we fabricate the new Ir(III) devices with different function layer thickness respectively and analyze the influence of the thickness change. Then we investigate the photophysical characteristics influenced by different host-guest doping concentration. Last, we fabricate the devices with the emission layer (EML) in different doping concentration and analyze the changes of device performance. This paper consists of six chapters. The first chapter mainly introduces the basic principles and development of OLED and PhOLED, with the brief introduction of (pbt)2Ir(acac) and it’s novel derivatives. The second chapter is aimed at the manufacture and measurement of the electrophosphorescent devices. The following three chapters focus on the four aspects of our research mentioned above, and the last chapter is the conclusion.(1) One of the new complexes, IrO, is used to dope CBP, PVK and TAZ in sarne concentration respectively, which are three different host materials, and the mixtures are fabricated into devices with structure ITO/PEDOT:PSS/EML/BCP/Alq3/LiF/Al. By studying the devices performance, we find that the sample with CBP has the best efficiency.(2) According to the result in (1), we change the thickness of EML, HBL (Hole-blocking layer) and ETL (Electron transport layer) respectively to analyze the influence to the devices performance, and find out the most appropriate thickness of that three function layer.(3) For the prognostication of the Electroluminescence characteristics (EL) of CBP:Ir(III) systems with new material, we respectively investigate the Photoluminescence characteristics, Lifetime and Time-resolved spectroscopy (TRES) of every CBP:Ir(III) systems with different new guest material in different doping concentration to analyze the luminescence procedure of them.(4) we fabricate the devices using the doping systems in (3) as EML to analyze the influence due to the difference of doping concentration that effect on the EL, and find out most of the devices have the best efficiency when doping concentration arrives nearly10%.