title: Labile or stable: can homoleptic and heteroleptic PyrPHOS-copper complexes be processed from solution?
abstract: Luminescent Cu(I) complexes are interesting candidates as dopants in organic light-emitting diodes (OLEDs). However, open questions remain regarding the stability of such complexes in solution and therefore their suitability for solution processing. Since the emission behavior of Cu(I) emitters often drastically differs between bulk and thin film samples, it cannot be excluded that changes such as partial decomposition or formation of alternative emitting compounds upon processing are responsible. In this study, we present three particularly interesting candidates of the recently established copper-halide-(diphenylphosphino)pyridine derivatives (PyrPHOS) family that do not show such changes. We compare single crystals, amorphous bulk samples, and neat thin films in order to verify whether the material remains stable upon processing. Solid-state nuclear magnetic resonance (MAS (31)P NMR) was used to investigate the electronic environment of the phosphorus atoms, and X-ray absorption spectroscopy at the Cu K edge provides insight into the local electronic and geometrical environment of the copper(I) metal centers of the samples. Our results suggest that--unlike other copper(I) complexes--the copper-halide-PyrPHOS clusters are significantly more stable upon processing and retain their initial structure upon quick precipitation as well as thin film processing.
authors.affiliation: Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT) , Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Volz
authors.forename: Manuela
authors.initials: M
authors.lastname: Wallesch
authors.forename: Stephan L
authors.initials: SL
authors.lastname: Grage
authors.forename: Jörg
authors.initials: J
authors.lastname: Göttlicher
authors.forename: Ralph
authors.initials: R
authors.lastname: Steininger
authors.forename: David
authors.initials: D
authors.lastname: Batchelor
authors.forename: Tonya
authors.initials: T
authors.lastname: Vitova
authors.forename: Anne S
authors.initials: AS
authors.lastname: Ulrich
authors.forename: Clemens
authors.initials: C
authors.lastname: Heske
authors.forename: Lothar
authors.initials: L
authors.lastname: Weinhardt
authors.forename: Thomas
authors.initials: T
authors.lastname: Baumann
authors.forename: Stefan
authors.initials: S
authors.lastname: Bräse
mesh_terms: D003300:Copper / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011725:Pyridines / Q000737:chemistry*; D012996:Solutions; D056928:X-Ray Absorption Spectroscopy
chemical_list: D011725:Pyridines; D012996:Solutions; D003300:Copper