A Novel Organic Light-emitting Materials Preparation And Performance Study

The heavy metals such as Ir, and Pt complexes have been widely employed as luminescent materials in OLED (Organic Light Emitting Diodes). Owing to the strong spin-orbital mixing of heavy-metal ions in phosphorescent complexes, both singlet and triplet excitons can be fully utilized, which creates the possibility for reaching a maximum internal efficiency of 100%. In these materials, iridium complexes have been regarded as one of 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. Cyclometalated iridium complexes using as electrophosphorescent materials were studied and are partly resolved present problems of electrophosphorescent materials and devices.Our studies are focused on the synthesis, characterization of new cyclometalated iridium complexes and electroluminescent properties in multilayer devices. The contexes are followed in this dissertation:1. Synthesis, characterization and luminescence study of iridium complexes with 2-arylpyridine and its derivates as cyclometalated ligands.A series of new cyclometalated ligands with different conjugation system and different substituents have been synthesized by changing 2-phenylpyridine. It is certainly possible to change the wavelength of emission of the complex by modifying the phenylpyridine ligand. Additional efforts show that it is possible to reduce self-quenching by the introduction of bulky groups on the basic phenylpyridine ligand. And also, fluorinated substituents on the aromatic ligand can result in markedly reduced concentration-quenching of luminescence, and excellent volatility which aids device processing. Reaction of these cyclometalated ligands with IrCl3·3H2O afforded the iridium complexes by changing different ancillary ligands. The obtained complexes have been characterized by 1H NMR, PL, and UV. The devices fabricated using the complexe Ir(DFPP)2(pic) as a dopant emitter has been achieved in a multilayer configuration. The maximum brightness of the device based on Ir(DFPP)2(pic) is 24220 cd/m2 with an external quantum efficiency of 3.05%. Its maximum efficiency is 5.47 cd/A2. Synthesis, characterization and luminescence study of iridium complexes with rigid cylcometalated ligandsA series.of new Iridiunm complexes with rigid cylcometalated ligands have been synthesized. The obtained complexes have been characterized by 1H NMR, PL and UV. The complex Ir(BIIO)2(pic) was used as an emitter in a multilayer configuration devices. The results showed that these complexes have strong phosphorescent characters. The device with a maximum external quantum efficiency of 11.2% and a maximum brightness of 79640 cd/m2 were achieved.