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CF3 Substitution of [Cu(P^P)(bpy)][PF6] complexes: Effects on Photophysical Properties and Light-emitting Electrochemical Cell Performance

Keller, Sarah and Brunner, Fabian and Junquera-Hernández, José M. and Pertegás, Antonio and La-Placa, Maria‐Grazia and Prescimone, Alessandro and Constable, Edwin C. and Bolink, Henk J. and Orti, Enrique and Housecroft, Catherine E.. (2018) CF3 Substitution of [Cu(P^P)(bpy)][PF6] complexes: Effects on Photophysical Properties and Light-emitting Electrochemical Cell Performance. ChemPlusChem, 83 (4). pp. 217-229.

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Official URL: https://edoc.unibas.ch/63499/

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Abstract

We report [Cu(P^P)(N^N)][PF 6 ] complexes with P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos), N^N = CF 3 -substituted 2,2'-bipyridines (6,6'-(CF 3 ) 2 bpy, 6-CF 3 bpy, 5,5'-(CF 3 ) 2 bpy, 4,4'-(CF 3 ) 2 bpy, 6,6'-Me 2 -4,4'-(CF 3 ) 2 bpy). We present the effects of CF 3 substitution on structures, and electrochemical and photophysical properties. The HOMO–LUMO gap is tuned by the N^N ligand; the largest redshift in the MLCT band is for [Cu(P^P)(5,5'-(CF 3 ) 2 bpy)][PF 6 ]. In solution, the compounds are weak yellow to red emitters. The emission properties depend on the substitution pattern but this cannot be explained by simple electronic arguments. For powders, [Cu(xantphos)(4,4'-(CF 3 ) 2 bpy)][PF 6 ] has the highest PLQY (50.3%) with an emission lifetime of 12 µs. Compared to 298 K solution behaviour, excited state lifetimes lengthen in frozen Me-THF (77 K) indicating thermally activated delayed fluorescence (TADF). TD-DFT calculations show that the energy gap between the lowest-energy singlet and triplet excited states (0.12–0.20 eV) permits TADF. LECs with [Cu(POP)(6-CF 3 bpy)][PF 6 ], [Cu(xantphos)(6-CF 3 bpy)][PF 6 ] or [Cu(xantphos)(6,6'-Me 2 -4,4'-(CF 3 ) 2 bpy)][PF 6 ] emit yellow electroluminescence. A LEC with [Cu(xantphos)(6,6'-Me 2 -4,4'-(CF 3 ) 2 bpy)][PF 6 ] had the fastest turn-on time (8 min); the LEC with the longest lifetime ( t 1/2 = 31 h) contained [Cu(xantphos)(6-CF 3 bpy)][PF 6 ]; these LECs reached maximum luminances of 131 and 109 cd m –2 .
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Constable)
05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Housecroft)
UniBasel Contributors:Housecroft, Catherine Elizabeth and Keller, Sarah and Brunner, Fabian and Prescimone, Alessandro and Constable, Edwin Charles
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Wiley
ISSN:2192-6506
Note:Publication type according to Uni Basel Research Database: Journal article -- The final publication is available at Wiley, see DOI link.
Language:English
Identification Number:
Last Modified:23 Apr 2018 07:03
Deposited On:23 Apr 2018 06:51

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