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  Dual Luminescence, Interligand Decay, and Nonradiative Electronic Relaxation of Cyclometalated Iridium Complexes in Solution

Pomarico, E., Silatani, M., Messina, F., Braem, O., Cannizzo, A., Barranoff, E., et al. (2016). Dual Luminescence, Interligand Decay, and Nonradiative Electronic Relaxation of Cyclometalated Iridium Complexes in Solution. The Journal of Physical Chemistry C, 120(30), 16459-16469. doi:10.1021/acs.jpcc.6b04896.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-3065-1 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-002B-3066-0
Genre: Journal Article


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http://dx.doi.org/10.1021/acs.jpcc.6b04896 (Publisher version)


Pomarico, Enrico1, 2, Author              
Silatani, M.1, Author
Messina, F.1, 3, Author
Braem, O.1, Author
Cannizzo, A.1, 4, Author
Barranoff, E.5, Author
Klein, J. H.6, Author
Lambert, C.6, 7, Author
Chergui, M.1, Author
1Laboratoire de Spectroscopie Ultrarapide (LSU) and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland, ou_persistent22              
2Quantum Condensed Matter Dynamics, Condensed Matter Dynamics Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society, ou_1938293              
3Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Palermo, Italy, ou_persistent22              
4Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland, ou_persistent22              
5School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom, ou_persistent22              
6Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany, ou_persistent22              
7UMR 5249 (Unité Mixte de Recherche) − LCBM − BIG − CEA, 17 Rue des Martyrs, 38054 Grenoble, France, ou_persistent22              


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 Abstract: Femtosecond broadband photoluminescence studies are presented for Ir(ppy)3 (Ir1), Ir(ppy)2(pic) (Ir2), Ir(ppy)2(bpy)(PF6) (Ir3), Ir(ppz)3 (Ir4), and Ir(ppz)2dipy (Ir5) (where ppy = 2-phenylpyridine, pic = picolinate, bpy = 2,2′-bipyridine, ppz = 1-phenylpyrazole, and dipy = 5-phenyldipyrrinato) in solution. Upon 400-nm excitation of Ir1–Ir3, we observed a prompt population of the lowest MLCT states. The higher states decay on an ultrafast time scale (<100 fs), whereas the lowest 3MLCT state undergoes further vibrational relaxation on a 1-ps time scale. In Ir3, this relaxation is accompanied by an interligand decay from the ppy to the bpy ligand in ∼1.5 ps. For the ppy-containing complexes (Ir1 and Ir2), we found that, at 100 ps, the luminescence is red-shifted with respect to the steady-state emission. This is explained in terms of a time-delayed dual luminescence, which we attribute to a double-well minimum configuration of the lowest emitting triplet states involving the ppy moiety. Ir4 shows a prompt population of the lowest excited state, which then undergoes vibrational relaxation in ∼0.5 ps. Finally, at short times, Ir5 exhibits fluorescence from the lowest 1LC state, which decays in ∼100 fs to the manifold of 3LC states. Overall, this study shows that, although the ultrafast relaxation to the lowest electronic states is quite similar to that of other transition-metal complexes, most of the differences occur at the lowest emissive states, with effects such as time-delayed dual fluorescence, interligand decay, and nonradiative relaxation to the ground or lower-lying metal-centered states. Understanding these effects is crucial for obtaining optimal performances of iridium complexes, calling for further iterations between chemical synthesis and photophysical studies to optimize these complexes.


Language(s): eng - English
 Dates: 2016-05-142016-07-062016-08-04
 Publication Status: Published in print
 Pages: 11
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1021/acs.jpcc.6b04896
 Degree: -



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Title: The Journal of Physical Chemistry C
  Abbreviation : J. Phys. Chem. C
Source Genre: Journal
Publ. Info: Washington DC : American Chemical Society
Pages: - Volume / Issue: 120 (30) Sequence Number: - Start / End Page: 16459 - 16469 Identifier: ISSN: 1932-7447
CoNE: https://pure.mpg.de/cone/journals/resource/954926947766