title: A Cyclic Alkyl(amino)carbene as Two-Atom π-Chromophore Leading to the First Phosphorescent Linear CuIComplexes.
abstract: The members of a series of linear and trigonal copper(I) complexes bearing a cyclic alkyl(amino)carbene (CAAC) ligand show surprising photophysical properties compared to those of the corresponding N-heterocyclic carbene (NHC) complexes. Whereas the linear NHC complexes [CuX(NHC)] are almost non-emissive, [CuX(CAAC)] (X=Cl, Br, I) and [Cu(CAAC)2]PF6show very bright emissions from their triplet excited states in the blue to green region, displaying quantum yields of up to 65 % in the solid state, even though the π-acceptor comprises only the carbene C and N atoms with no other π conjugation. [Cu(CAAC)2]PF6is the fastest CuI-based triplet state emitter characterized to date, not displaying thermally activated delayed fluorescence (TADF), with an intrinsic lifetime of only 10.6 μs, that is, kr=9.4×104s-1, competitive with many PtII- and IrIII-based emitters. In order to test the stability of such linear copper CAAC complexes in devices, some of our compounds have been applied in proof-of-principle organic light-emitting diodes (OLEDs). This case study thus demonstrates for the first time the use of CAACs as suitable π-chromophores for CuI-based phosphorescent emitters, and their implementation in OLEDs underlines the general applicability of this class of ligands in materials science.
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Gernert
authors.affiliation: Experimentelle Physik VI, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Müller
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Haehnel
authors.affiliation: Experimentelle Physik VI, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Pflaum
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Steffen
keywords: chromophores; copper; intersystem crossing; phosphorescence; spin-orbit coupling