Electronic Relaxation Processes in the T1 State of Phosphorescent fac-Tris(2-phenylpyridine) Iridium Molecule in 4,4'-N,N'-Dicarbazole-biphenyl Host

Abstract

We have analyzed the time-resolved photoluminescence spectra of fac-tris(2-phenylpyridine) iridium [Ir(ppy)3] doped in 4,4'-N,N'-dicarbazole-biphenyl (CBP) using the spin–phonon relaxation processes among three zero-field splitting substates of the T1 triplet state under the Franck–Condon principle. Good agreement was obtained between the calculated and measured results regarding temperature dependence of three decay components, red peak shift during time evolution at 5 K, and luminescence line shape with vibronic structure.