No abstract

Iridium complexes containing cyclometalated 2‐cyclohexenylpyridine derivatives with rigid and bulky cyclohexene units are synthesized, and found to be highly efficient materials in EL devices (see figure). Devices based on these iridium complexes emit yellowish‐ green light with the very high external quantum efficiency of 18.7%.

We report the synthesis and device characterization of a novel iridium complex using a phenylpyridine derivative containing an imide functional group as a bis-cyclometallized ligand ((impy) 2 Ir(acac)) for orange organic light-emitting diodes (OLEDs). The photoluminescence of the dopant emits orange light with the main peak of 560 nm and a shoulder of 595 nm. The OLEDs made with the synthesized dopant also produce intense orange electroluminescence at 568-572 nm wavelengths depending on the device geometry. Very high peak external quantum efficiencies of 13.8-14.4%, peak power efficiencies of 29.2-32.7 lm/W, and low operation voltages of 5.3-5.4 V at 1000 cd/m 2 have been demonstrated for the orange OLEDs.Scheme 1 Synthesis of iridium(III) bis(2-isopropyl-5-(pyridin-2-yl)isoindoline-1,3-dione-N,C 2 0 )(acetyl acetonate).

A new p-type conjugated copolymer, poly(9,10-diethynylanthracene-alt-9,9-didodecylfluorene) (PDADF), which is composed of ethynyl-linked alternating anthracene/fluorene, is synthesized via a palladium(II)-catalyzed Sonogashira coupling reaction with 9,10-diethynylanthracene and 2,7-diiodo-9,9-didodecyl-fluorene. The obtained polymer is confirmed by FTIR, 1 H-NMR, 13 C-NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is À5.62 eV as measured via cyclic voltammetry (CV). A solutionprocessed thin film transistor device showed a carrier mobility value of 6.0 Â 10 À4 cm 2 /Vs with a threshold voltage of À17 V and a capacitance (C i ) of 10 nF/cm 2 . The out-of-plane and in-plane GIXD pattern of spin-coated polymer on SiO 2 dielectric surfaces showed an amorphous halo near 2h ¼ 20 . V

Small‐fused acenes with an electron‐donating alkoxyl naphthyl end‐capper, which can tune the electronic properties and increase stacking by self‐assembly, are synthesized by a simple process and fabricated into organic thin film transistors. In particular, hexyloxynaphthalene‐end‐capped anthracene, AN‐ANE (see figure), shows field effect mobility three times that of pentacene under optimized conditions.