Synthesis And Photo/Electro Luminescence Property Study Of Novel Oxadiazoles Ligands And Their Iridium Complexes

In recent years, solid-state light-emitting electrochemical cell （LECs） have attracted agreat deal of interest. Compared with conventional organic light-emitting diodes （OLEDs）,LECs are more popular in practical applications because of the simple structure, easypreparation, no special requirements on the metal electrode, low starting voltage, highefficiency and and other advantages.With the reported of LECs based on a cationic transition metal complex in1996byRubner et al, ionic transition metal complexes （iTMCs）-based LECs received more and moreattention because of their several advantages over conventional polymer-based LECs. First,because of carrying the charge and counter-ions, ionic transition metal complexes have ionconductivity, which in favor of carrier injection and transport and can reduce device powerconsumption. Besides, they show good thermal and photophysical stabilities. Furthermore,high electroluminescence （EL） efficiencies is expected because of the phosphorescent natureof the metal complexes. However, as a result of the higher ligand-field spitting energy of thetrivalent iridium ion, and shorter phosphorescence life and higher luminescent efficiency andtunable light emission color, ionic iridium complexes are most widely researched inelectroluminescence.1,3,4-oxadiazole derivatives have excellent electronic transmission, good luminescenceproperties, thermal and chemical stability, so they have become one of the most widely usedelectron transport materials in the application and research. As electron-transporting andhole-blocking material,1,3,4-oxadiazole derivatives have been introduced into cyclometalatedligands of iridium complexes to enhance their phtoelectronic properties. They have got wellapplication in organic light-emitting devices.Therefore, in this article a series of1,3,4-oxadiazole ligands which have beensynthesized will be used to coordination with iridium, finally we get six ionic iridiumcomplexes. We fabricate light-emitting electrochemical cells based on the six complexes asemitting layer respectively, and study their photoluminescence and electroluminescenceproperties in detail.The main content of this thesis is as follows:1. We designed and synthesized a number of1,3,4-oxadiazole ligands, and coordinationwith iridium, finally we got six ionic iridium（Ⅲ） complexes. They are （1）[Ir（OXD）₂（ptop）]⁺（PF₆^-）,（2）[Ir（OXD）₂（mptop）]⁺（PF₆^-），（3）[Ir（dcOXD）₂（ptop）]⁺（PF₆^-）,（4）[Ir（dcOXD）₂（mptop）]⁺（PF₆^-）,（5）[Ir（dmOXD）₂（ptop）]⁺（PF₆^-） and （6）[Ir（dmOXD）₂（mptop）]⁺（PF₆^-）, where ptop, mptop, OXD, dcOXD and dmOXD are2-（5-phenyl-1,3,4-oxadiazol-2-yl）pyridine,2-（5-p-tolyl-1,3,4-oxadiazol-2-yl）pyridine,2,5-Diphenyl-1,3,4-oxadiazole,2,5-bis（4-methyl）phenyl-1,3,4-oxadiazol,2,5-bis（4-methoxy）phenyl-1,3,4-oxadiazol, respectively. These complexes are characterized by IR spectra, NMR spectra and single crystal structure.2. We studied the photoluminescence properties of six complexes, and explained therelationship between photophysical properties and chemical structure of the complexes byquantitative calculation. Electrochemical properties and phosphorescence quantum yields ofthese complexes were investigated.3. We fabricated light-emitting electrochemical cells based on the six complexes asemitting layer respectively, and then studied their electroluminescent properties. Weinvestigated their properties, such as the maximum brightness, electroluminescence spectra,CIE, lifetime, current density and so on.