Synthesis Of Red-emitting Irdium Complexes And Their Electrophosphorescence Devices

Organic light-emitting diodes (OLEDs) have attracted more attention due to their potential application in flat-panel display and semiconductor lighting. However, the highly efficient pure-red-emitting complexes are still scarce in the realization of full-color display. Cyclometalated iridium (Ⅲ) complexes with organic fluorescent ligands can show strong triplet emission at room temperature with high quantum efficiency, so the research on organic red phosphorescent materials constitutes a major scientific frontier in OELDs.Four new tris-cyclometalated iridium complexes with benzothiazol derivative ligands have been designed and synthesized through the modificaiotn of ligands. In order to enlarge conjugation systerm and reduce triplet energy, the groups such fluorenyl containg aliphatic chains were introduced into benzothiazol ring in two of compounds, as well as with the expeicton that excellent efficiency and color purity can be improved by good performance and film-forming characterstic of fluorene-derived groups.Another two complexes with the structures containing indenyl weren't in deep research duo to their week dark-red light emission,with the consequence of limited appilication in OLEDs. The structures of four compounds have been confirmed by 1HNMR and MS, which their photophysics, electrochemistry properties are also studied by means of UV-Vis absorption, photoluminescence spectrum and cyclic voltammetry.As indicatied, the first two complexes not only approach to red luminence in solution and solid state, but also have taken the advantage of the fluorene module in the ligand framework demonstrated by an improved hole-injection ability.Here, we also report two highly efficient organc-red devices using two newly synthesized iridium complexes as phosphorescent dopant into host material (CBP) by menas of vacuum-deposited teconology.After examining the luminance-voltage-current density and luminous efficiency-current density characteristics for the devices doped with 5wt% compounds,it has been indicatied that sufficient energy from CBP to iridium dopant emitters can facilitate the pure orange-red phosphrecent luminescence.with a maximum emission wavelength at 600nm and 588nm.Morever, device A had a turn on voltage of 4.8V, a maximum luminance of 16160 cd/m2 and a maximum efficency of 15.48cd/A and 7.681m/W. Also, emission with CIE coordinates (0.63,0.36) was close to the standard red.In comparison with device A,device B had a turn on voltage of 5V, a maximum of 36760 cd/m2 and a maximum luminance efficency of 30cd/A and 14.01m/W also with CIE coordinates (0.59,0.40). In conclusion, the above iridium complexes with high efficiency and excellent purity can basically meet the needs of red light-emitting requirements in the full color.