| This dissertation simply summarizes the development of cyclometalated platinum/iridium based phosphorescent materials. In order to enrich the broad emission materials based on monomolecule and fluorescent/phosphorescent dual-emission materials, and further to address the molecular building and study photophysical properties, we would plan to explore the relationship between cyclometallated complex and fluorescent/phosphorescent emission. Therefore, three dinuclear cyclometallated platinum complexes and four mononuclear cyclometallated iridium complexes have been designed and synthesized. The structures of these complexes were confirmed by 1H NMR, 13 C NMR, elemental analysis and TOF-MS. Additionlly, we used UV-vis absorption spectra, photoluminescent spectra, transient absorption, cyclic voltammetry, thermal analysis(TGA and DSC) and polarized optical microscopy(POM) to investigate the optophysical properties, electrochemical and thermal properties of these complexes. The main contents of this dissertation are listed as follows:1. Three dinuclear cyclometalated platinum complexes, named as Pt-1、Pt-2、Pt-3, were achieved, in which the Indeno[1,2-b]fluorine derivatives are considered as bridge unit, naphthylpyridine as the cyclometallating ligand and acetylaceton(acac) or dibenzoylmethane(DBM) as the ancillary ligand. The effect of alkoxy numbers and ancillary ligand on the photophysical properties of dinuclear platinum complexes were explored in detail. TGA, DSC and POM suggests that these platinum complexes possess a good thermal stability, and they show the smectic liquid crystal in a certain temperature range. The PL spectra of these platinum complexes exhibit the fluorescent(532-572 nm)/phosphorescent(630-650 nm) dual emissions in CH2Cl2 solution. The mechanism of fluorescent/phosphorescent dual emissions were explored by transient absorption, low-temperature PL, time-resolved spectra and theory calculation. The organic light-emitting diodes(OLEDs) based on Pt-1 were fabricated, and the devcies performances were preliminary studied.2. Four cationic cyclometalated Iridium complexes, named as Ir-1、Ir-2、Ir-3、Ir-4, were designed and prepared, in which perylene diimide is considered as the ancillary ligand and phenylpyridine derivatives as the cyclometallated ligand. All of these cationic cyclometalated iridium complexes exhibit good thermal stability with a decomposition temperature above 250 oC(5 wt%). At low concentration(10-5 M), these iridium complexes show the maximum emission peak at about 491-516 nm in CHCl3 solution, which is ascribed to the fluorescent emission caused by ligand-centre transport transiton. At high concentration(10-2 M), these iridium complexes show the emission in the near-infrared region( ~ 750 nm), which is attributed to the phosphorescent emission. Compred to the emission in solution, all the iridium complexes show only the emission in long wavelength between 750 nm and 757 nm. In addition, we found that there is negligible effect of cyclometalating ligand on the photophysical property of the ionic iridium complex. To further investigate the relationship between electronic transition and molecular strcutre, we carried out by the theory calculation based on Gaussian 09 program.The study investigated the relationship between the structure of cyclometalated complex and their photophyscail properties in detail. Therefore, the rule of building the fluorescent/phosphorescent dual emission materials based on cyclometallated platinum/iridium complex have been revealed, which plays a significant for the monomolecule-based broad emission materials. Unfortunately, these platinum and iridium complexes have some problems to settle, for example, the low emission efficiency, complicated synthetic route and an unstatified device performance. Therefore, we need to have some proposals to address these issues in further research. |
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