Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells
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Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells

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Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells

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dc.contributor.author Brunner, Fabian
dc.contributor.author Babaei, Azin
dc.contributor.author Pertegás Ojeda, Antonio
dc.contributor.author Junquera-Hernández, José M.
dc.contributor.author Prescimone, Alessandro
dc.contributor.author Constable, Edwin C.
dc.contributor.author Bolink, Henk
dc.contributor.author Sessolo, Michele
dc.contributor.author Ortí Guillén, Enrique
dc.contributor.author Housecroft, Catherine E.
dc.date.accessioned 2020-06-19T09:16:26Z
dc.date.available 2020-06-19T09:16:26Z
dc.date.issued 2019
dc.identifier.uri https://hdl.handle.net/10550/75141
dc.description.abstract The synthesis and characterization of five [Cu(P^P)(N^N)][PF6] complexes in which P^P = 2,7-bis(tert-butyl)-4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (tBu2xantphos) or the chiral 4,5-bis(mesitylphenylphosphino)-9,9-dimethylxanthene (xantphosMes2) and N^N = 2,2'-bipyridine (bpy), 6-methyl-2,2'-bipyridine (6-Mebpy) or 6,6'-dimethyl-2,2'-bipyridine (6,6'-Me2bpy) are reported. Single crystal structures of four of the compounds confirm that the copper(I) centre is in a distorted tetrahedral environment. In [Cu(xantphosMes2)(6-Mebpy)][PF6], the 6-Mebpy unit is disordered over two equally populated orientations and this disorder parallels a combination of two dynamic processes which we propose for [Cu(xantphosMes2)(N^N)]+ cations in solution. Density functional theory (DFT) calculations reveal that the energy difference between the two conformers observed in the solid-state structure of [Cu(xantphosMes2)(6-Mebpy)][PF6] differ in energy by only 0.28 kcal mol‒1. Upon excitation into the MLCT region (λexc = 365 nm), the [Cu(P^P)(N^N)][PF6] compounds are yellow to orange emitters. Increasing the number of Me groups in the bpy unit shifts the emission to higher energies, and moves the Cu+/Cu2+ oxidation to higher potentials. Photoluminescence quantum yields (PLQYs) of the compounds are low in solution, but in the solid state, PLQYs of up to 59% (for [Cu(tBu2xantphos)(6,6'-Me2bpy)]+) are observed. Greatly increased excited-state lifetimes at low temperature are consistent with the complexes exhibiting thermally activated delayed fluorescence (TADF). This is supported by the small energy difference calculated between the lowest-energy singlet and triplet excited states (0.17-0.25 eV). The compounds were tested in simple bilayer light-emitting electrochemical cells (LECs). The optoelectronic performances of complexes containing xantphosMes2 were generally lower with respect to those with tBu2-xantphos, which led to bright and efficient devices. The best performing LECs were obtained for the complex [Cu(tBu2xantphos)(6,6'-Me2bpy)][PF6] due to the increased steric hindrance at the N^N ligand resulting in higher PLQY.
dc.language.iso eng
dc.relation.ispartof Dalton Transactions, 2019, vol. 48, num. 2, p. 446-460
dc.rights.uri info:eu-repo/semantics/openAccess
dc.source Brunner, Fabian Babaei, Azin Pertegás Ojeda, Antonio Junquera-Hernández, José M. Prescimone, Alessandro Constable, Edwin C. Bolink, Henk Sessolo, Michele Ortí Guillén, Enrique Housecroft, Catherine E. 2019 Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells Dalton Transactions 48 2 446 460
dc.subject Electroquímica
dc.title Phosphane tuning in heteroleptic [Cu(N^N)(P^P)]+ complexes for light-emitting electrochemical cells
dc.type info:eu-repo/semantics/article
dc.date.updated 2020-06-19T09:16:27Z
dc.identifier.doi https://doi.org/10.1039/C8DT03827A
dc.identifier.idgrec 129832

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