Quantum chemistry investigation on the photophysical properties of phosphorescent iridium(III) complexes with modified cyclometalating ligands

Based on the quantum chemistry methodologies, the electronic structures and photophysical properties have been investigated for a series of cyclometalated iridium(III) complexes Ir(C boolean AND N)(2)(acac), including 1 [C boolean AND N = 2-biphenyl-4-yl-quinoline], 2 [C boolean AND N = 2-(fluoren-2-y1)-quinoline], 3 [C boolean AND N = 2-dibenzofuran-3-yl-quinoline], 4 [C boolean AND N = 2-dibenzothiophen-3-yl-quinoline] and 5 [C boolean AND N = 2-phenanthren-2-yl-quinoline]. The electronic configurations, absorption properties, emission wavelengths and the potential phosphorescent performances have been outlined for each of the complexes. On the basis of the two simplifications presented in this paper and the available experimental data, the magnitudes of phosphorescent radiative rates for each of the complexes were approximately calculated to be: 1.20 x 10(5)s(-1), 8.75 x 10(4)s(-1), 3.58 x 10(5)s(-1), 5.69 x 10(4) s(-1) and 4.73 x 10(4)s(-1), respectively. Meanwhile, the sequence of phosphorescent quantum efficiencies was obtained to be: Phi(PL)(3)> Phi(PL)(1) > Phi(PL)(2) > Phi(PL)(5) > Phi(PL)(4). Our research work is of great importance, consulting the quantum chemistry conclusions and applying adequate chemical engineering, it may be possible to obtain cyclometalated iridium(III) complexes with distinctly improved phosphorescent performances in the application in OLED. (C) 2015 Elsevier Ltd. All rights reserved.