Novel phosphorescent triptycene-based Ir(iii) complexes for organic light-emitting diodes.

A series of charge-neutral cyclometalated iridium(iii) complexes (1-3 and 5-7) containing triptycene-substituted ligands (tbt and tpbi) and two parent complexes (4 and 8) were synthesized and characterized. The crystal structures indicated that π-π stacking interactions existed in ligand tbtH, but not in complex 6. However, a large intramolecular repulsion was found in complex 6. These triptycene-based complexes exhibited good thermal stability, which was higher compared with that of the parent complexes. These complexes showed green to yellow emission with peaks that ranged from 503 to 563 nm. The introduction of the rigid non-conjugate triptycene skeleton caused a slight emission red shift (<25 nm), but a significant increase in the PLQYs (>47%) was observed. The electroluminescent devices employing 2 and 6 as phosphors displayed impressive performance improvements and low efficiency roll-off because of the higher PLQYs and HOMO levels of these triptycene-based complexes. The maximum current and external quantum efficiencies of the devices based on complexes 2 and 6 were 41.7 cd A-1, 11.9% and 41.2 cd A-1, 12.6%, respectively, which were about 31% higher than that of the devices based on the parent complexes 4 and 8. This work provides a novel approach to develop highly efficient phosphors with a triptycene skeleton.

Solution processed single-emission layer white polymer light-emitting diodes with high color quality and high performance from a poly(N-vinyl)carbazole host.

Low cost and high performance white polymer light-emitting diodes (PLEDs) are very important as solid-state lighting sources. In this research three commercially available phosphors were carefully chosen, bis[2-(4,6-difluorophenyl)pyridinato-N,C(2)](picolinate)iridium(III) (FIrpic), bis[2-(2-pyridinyl-N)phenyl-C](2,4-pentanedionato-O(2),O(4))iridium(III) [Ir(ppy)2(acac)], and bis(2-phenyl-benzothiazole-C(2),N)(acetylacetonate)iridium(III) [Ir(bt)2(acac)], plus a home-made red phosphor of tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III) [Ir(MPCPPZ)3], and their photophysical and morphological properties were systematically studied as well as their applications in single-emission layer white PLEDs comprising poly(N-vinylcarbazole) as host. Additionally, the electrochemical properties and energy level alignment, possible energy transfer process, and thin-film morphology were also addressed. The binary blue/orange complementary white PLEDs exhibit stable electroluminescence spectra, wide spectrum-covering region range from 380-780 nm, and high color rendering index (CRI) over 70 with Commission Internationale de l'Eclairage coordinates x,y (CIEx,y) of (0.388, 0.440), correlated color temperature (CCT) of around 4400, plus high efficiency of 25.5 cd A(-1). The optimized red-green-blue white PLEDs showed a satisfactory CRI of around 82.4, maximum current efficiency of 20.0 cd A(-1) and external quantum efficiency (EQE) of 10.8%, corresponding to a CCT of 3700-2800, which is a warm-white hue. At last, stable and high color quality, red-green-orange-blue four component white PLEDs, with a CRI of over 82, a high efficiency of 24.0 cd A(-1), EQE of 11.5%, and high brightness of 43,569.9 cd m(-2) have been obtained.

Phosphorescent chemosensor for Hg2+ and acetonitrile based on iridium(III) complex.

A new phosphorescent chemosensor for Hg(2+) and acetonitrile (MeCN) based on iridium(III) complex Ir(dpp)(2)(dtc) (Ir1, dppH = 4,6-diphenylpyrimidine, dtcH = diethyl dithiocarbamic acid) was realized. Upon addition of a tetrahydrofuran (THF) solution of Hg(2+), the dichloromethane (DCM) solution of Ir1 gave a visual color change and significant fluorescent quenching. When MeCN was added, a new fluorescent emission emerged, which constituted a selective MeCN phosphorescent chemosensor. Complex Ir1 has been developed as an AND logic gate with Hg(2+) and MeCN as inputs.