Synthesis and characterization of a new iridium(III) complex with bulky trimethylsilylxylene and applications for efficient yellow-green emitting phosphorescent organic light emitting diodes

We designed and synthesized a new iridium(III) complex with phenylpyridine ligands containing a bulky trimethylsilylxylene, 5-(2,5-dimethyl-4-(trimethylsilyl)phenyl)-2-phenylpyridine, by Suzuki coupling reaction and characterized using various spectroscopic studies. Nuclear magnetic resonance studies show its structure to be that of a facial isomer. Thermogravimetric analysis and differential scanning calorimetry studies show its higher thermal stability (∆T5%) of 638 K with a glass transition temperature of 425 K. It shows the photoluminescence emission at 532 nm in solution with the band gap energy of 2.56 eV. The new iridium(III) complex as dopant in phosphorescent organic light emitting diodes exhibits the yellow-green emission at 532 nm as it effectively hinders aggregation formation in the solid state at a dopant concentration of 6%, resulting in higher device efficiencies of 12.7% and 45.7 cd/A. The results show that the new iridium complex could be useful in white organic light emitting diodes for the lighting applications.

► Ir(dmtppy)3 shows the PL emission at 532 nm in solution with the band gap energy of 2.56 eV. ► It exhibits the higher thermal stability (∆T5%) of 365 °C with the glass transition temperature (Tg) of 152 °C. ► Ir(dmtppy)3 dopant in phosphorescent OLED emits the yellow-green emission at 532 nm with CIE color coordinates of (0.37, 0.60). ► It effectively hinders the formation of aggregation in solid state for dopant concentration of 6% in CBP. ► The higher device efficiencies of 12.7% and 45.7 cd/A were observed.