Design and development of an unprecedented phosphorescent bidentate iridium (III) complex exhibiting green electroluminescence

The present study comprises of design, synthesis and characterization of a novel Ir(III) based triplet emitter well supported by theoretical modelling via DFT. The imperative structural conformation of the complex was accomplished through NMR, FTIR and elemental (CHNS) analysis. The molecule was then subjected to photophysical measurements to investigate the various kinds of transitions occurring upon optical excitation. Further, utilizing TRPL measurements, the compound was examined to have an excited state lifetime of 0.06 µs and a photoluminescence quantum yield of 0.18. Affirmative to the results shown by photoluminescence studies, the molecule exhibits stable green electroluminescence at 510 nm at room temperature. For a better understanding of experimental observations, first principles quantum mechanical studies have been performed, aimed at geometry optimization, electronic structures, and luminescence properties of the synthesized Ir(III) complex and participating ligands within the framework of density functional theory (DFT) using the B3LYP functional. The absorption spectra of the complex have been computed using TD-DFT and the emission spectra (phosphorescence) were sketched based on the results obtained from the vibronic analysis, whereby the vibronic contributions to electronic emission were considered using the adiabatic shift (AS) approach as implemented in the Gaussian 09 software package.