The shiny side of copper: bringing copper(i) light-emitting electrochemical cells closer to application. Issue 38 (16th June 2020)

• Record Type: Journal Article
• Authors: Keller, Sarah; Prescimone, Alessandro; La Placa, Maria-Grazia; Junquera-Hernández, José M.; Bolink, Henk J.; Constable, Edwin C.; Sessolo, Michele; Ortí, Enrique; Housecroft, Catherine E.
• Is Part Of: RSC advances. Volume 10:Issue 38(2020)
• Page Start: 22631
• Page End: 22644
• Publication Date: 2020-06-16
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0ra03824e
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Heteroleptic copper(i ) complexes with bisphosphanes and astutely tuned N^N chelating ligands as emitters give bright LECs with record-breaking stability. Abstract : Heteroleptic [Cu(P^P)(N^N)][PF6 ] complexes, where N^N is 5, 5′-dimethyl-2, 2′-bipyridine (5, 5′-Me2 bpy), 4, 5, 6-trimethyl-2, 2′-bipyridine (4, 5, 6-Me3 bpy), 6-( tert -butyl)-2, 2′-bipyridine (6- t Bubpy) and 2-ethyl-1, 10-phenanthroline (2-Etphen) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP, PIN [oxydi(2, 1-phenylene)]bis(diphenylphosphane)) or 4, 5-bis(diphenylphosphino)-9, 9-dimethylxanthene (xantphos, PIN (9, 9-dimethyl-9 H -xanthene-4, 5-diyl)bis(diphenylphosphane)) have been synthesized and their NMR spectroscopic, mass spectrometric, structural, electrochemical and photophysical properties were investigated. The single-crystal structures of [Cu(POP)(5, 5′-Me2 bpy)][PF6 ], [Cu(xantphos)(5, 5′-Me2 bpy)][PF6 ], [Cu(POP)(6- t Bubpy)][PF6 ], [Cu(POP)(4, 5, 6-Me3 bpy)][PF6 ]·1.5Et2 O, [Cu(xantphos)(4, 5, 6-Me3 bpy)][PF6 ]·2.33CH2 Cl2, [Cu(POP)(2-Etphen)][PF6 ] and [Cu(xantphos)(2-Etphen)][PF6 ] are described. While alkyl substituents in general exhibit electron-donating properties, variation in the nature and substitution-position of the alkyl group in the N^N chelate leads to different effects in the photophysical properties of the [Cu(P^P)(N^N)][PF6 ] complexes. In the solid state, the complexes are yellow to green emitters with emission maxima between 518 and 602 nm, and photoluminescence quantum yields (PLQYs) ranging from 1.1 to 58.8%. All complexes show thermally activated delayed fluorescence (TADF). The complexes were employed in the active layer of light-emitting electrochemical cells (LECs). The device performance properties are among the best reported for copper-based LECs, with maximum luminance values of up to 462 cd m −2 and device half-lifetimes of up to 98 hours.