DFT/TD-DFT Study on the Electronic Structures and Optoelectronic Properties of Several Blue-Emitting Iridium(III) Complexes

The electronic structures and optoelectronic properties of several blue-emitting phosphors (dfppy)(2)Ir(pyN2), (dfppy)Ir(pyN2)(2), and (fpmb)(2)Ir(pyN3) [dfppyH: 2-(2,4-difluorophenyl)pyridine; pyN2H: 5-(2-pyridyl)-3-trifluoromethylpyrazole; Hfpmb: 1-(4-fluorophenyl)-2,3-dihydro-3-methyl-1H-benzo[d]imidazole; and pyN3H: 2-(5-(trifluoromethyl)-2H-1,2,4-triazol-3-yl)pyridine] are investigated with density functional theory. The injection abilities of holes and electrons are estimated by evaluating the ionization potentials and electron affinities. It is found that the properties of the ligands have great influence on the photophysical properties, such as energy gap, absorption spectra, emission spectra, etc. The assumed complex (dfppy)(2)Ir(pyN2) is found to be a good candidate for blue-emitting material. We suggest that the luminescent properties of this class of materials can be tuned by modifications of the corresponding ligands.