Niehaus, Thomas A. and Hofbeck, Thomas and Yersin, Hartmut (2015) Charge-transfer excited states in phosphorescent organo-transition metal compounds: a difficult case for time dependent density functional theory? RSC ADVANCES, 5 (78). pp. 63318-63329. ISSN 2046-2069,
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Light emitting organo-transition metal complexes have found widespread use in the past. The computational modelling of such compounds is often based on time-dependent density functional theory (TDDFT), which enjoys popularity due to its numerical efficiency and simple black-box character. It is well known, however, that TDDFT notoriously underestimates energies of charge-transfer excited states which are prominent in phosphorescent metal-organic compounds. In this study, we investigate whether TDDFT is providing a reliable description of the electronic properties in these systems. To this end, we compute 0-0 triplet state energies for a series of 17 pseudo-square planar platinum(II) and pseudo-octahedral iridium(III) complexes that are known to feature quite different localization characteristics ranging from ligand-centered (LC) to metal-to-ligand charge transfer (MLCT) transitions. The calculations are performed with conventional semi-local and hybrid functionals as well as with optimally tuned range-separated functionals that were recently shown to overcome the charge transfer problem in TDDFT. We compare our results against low temperature experimental data and propose a criterion to classify excited states based on wave function localization. In addition, singlet absorption energies and singlet-triplet splittings are evaluated for a subset of the compounds and are also validated against experimental data. Our results indicate that for the investigated complexes charge-transfer is much less pronounced than previously believed.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | GENERALIZED-GRADIENT-APPROXIMATION; VIBRATIONAL SATELLITE STRUCTURES; OLED EMITTER IR(BTP)(2)(ACAC); ELECTRONIC STATES; TRIPLET-STATE; ORGANOMETALLIC COMPLEXES; PHOTOPHYSICAL PROPERTIES; EFFICIENCY; EXCHANGE; EXCITATIONS; |
| Subjects: | 500 Science > 530 Physics 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Physics > Institute of Theroretical Physics Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry III - Physical Chemistry (Molecular Spectroscopy and Photochemistry) > Prof. Dr. Hartmut Yersin |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 30 Jul 2019 14:10 |
| Last Modified: | 30 Jul 2019 14:10 |
| URI: | https://pred.uni-regensburg.de/id/eprint/6227 |
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