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)2pic], by Suzuki coupling reaction and confirmed using various spectroscopic studies. The Thermogravimetric analysis shows the 5% weight loss (ΔT5%) at 356 °C with the glass transition temperature (Tg) of 198 °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)2pic 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.

► New Ir(dmtppy)2pic shows the PL emission at 520 nm in solution.
► Ir(dmtppy)2pic has high thermal stability (ΔT5%: 356 °C and Tg: 198 °C).
► Ir(dmtppy)2pic in phosphorescent OLED emits the yellow-green emission.
► The higher device efficiencies of 10.2%, 30.2 cd/A and 10.1 lm/W were observed.