A new bulky trymethylsilylxylene substituted iridium(III) complex with picolinic acid as ancillary ligand: Synthesis; characterization and applications for efficient yellow-green emitting phosphorescent organic light emitting diodes

We designed and synthesized a new bulky trimethylsilylxylene substituted iridium(III) complex with picolinic acid as ancillary ligand, bis(5-(2,5-dimethyl-4-(trimethylsilyl)phenyl)-2-phenylpyridine)iridium(III) picolinate [Ir(dmtppy)(2)pic], by Suzuki coupling reaction and confirmed using various spectroscopic studies. The Thermogravimetric analysis shows the 5% weight loss (Delta T-5%) at 356 degrees C with the glass transition temperature (T-g) of 198 degrees C from differential scanning calorimetry studies. The photophysical and electrochemical studies show the photoluminescence emission at 520 nm (in solution) with the band gap energy of 2.59 eV. Ir(dmtppy)(2)pic dopant in phosphorescent organic light emitting diodes exhibits the yellow-green emission at 528 nm with CIE color coordinates of (0.37, 0.58) with higher device current efficiency of 30.2 cd/A, the external quantum efficiency of 10.2% and the power efficiency of 10.1 lm/W. (C) 2011 Elsevier B.V. All rights reserved.