Role of electronic localization in the phosphorescence of iridium sensitizing dyes.
In this work we present a systematic study of three representative iridium dyes, namely, Ir(ppy)(3), FIrpic, and PQIr, which are commonly used as sensitizers in organic optoelectronic devices. We show that electronic correlations play a crucial role in determining the excited-state energies in these systems, due to localization of electrons on Ir d orbitals. Electronic localization is captured by employing hybrid functionals within time-dependent density-functional theory and with Hubbard-model corrections within the Δ-SCF approach. The performance of both methods are studied comparatively and shown to be in good agreement with experiment. The Hubbard-corrected functionals provide further insight into the localization of electrons and on the charge-transfer character of excited-states. The gained insight allows us to comment on envisioned functionalization strategies to improve the performance of these systems. Complementary discussions on the Δ-SCF method are also presented in order to fill some of the gaps in the literature.
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Burak
B
Himmetoglu
Alex
A
Marchenko
Ismaïla
I
Dabo
Matteo
M
Cococcioni