title: Towards Printed Organic Light-Emitting Devices: A Solution-Stable, Highly Soluble CuI-NHetPHOS.
abstract: The development of iridium-free, yet efficient emitters with thermally activated delayed fluorescence (TADF) was an important step towards mass production of organic light-emitting diodes (OLEDs). Progress is currently impeded by the low solubility and low chemical stability of the materials. Herein, we present a CuI-based TADF emitter that is sufficiently chemically stable under ambient conditions and can be processed by printing techniques. The solubility is drastically enhanced (to 100 g L-1) in relevant printing solvents. The integrity of the complex is preserved in solution, as was demonstrated by X-ray absorption spectroscopy and other techniques. In addition, it was found that the optoelectronic properties are not affected even when partly processing under ambient conditions. As a highlight, we present a TADF-based OLED device that reached an efficiency of 11±2 % external quantum efficiency (EQE).
authors.affiliation: Institute of Toxicology and Genetics and Institute of Organic Chemistry, Karlsruhe Institute of Technology, Kaiserstrasse 12, 76131, Karlsruhe, Germany.
authors.forename: Manuela
authors.initials: M
authors.lastname: Wallesch
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Anand
authors.initials: A
authors.lastname: Verma
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Fléchon
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Flügge
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Zink
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Seifermann
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: José M
authors.initials: JM
authors.lastname: Navarro
authors.affiliation: Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, P.O. 3640, 76021, Karlsruhe, Germany.
authors.forename: Tonya
authors.initials: T
authors.lastname: Vitova
authors.affiliation: Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Göttlicher
authors.affiliation: Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Steininger
authors.affiliation: Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany.|Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology, Engesserstrasse 18/20, 76128, Karlsruhe, Germany.|Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Pkwy, Las Vegas, NV, 89154-4003, USA.
authors.forename: Lothar
authors.initials: L
authors.lastname: Weinhardt
authors.affiliation: University of Kaiserslautern, Chemistry Department and Research Center OPTIMAS, Erwin-Schrödinger-Strasse 52, 67663, Kaiserslautern, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Zimmer
authors.affiliation: University of Kaiserslautern, Chemistry Department and Research Center OPTIMAS, Erwin-Schrödinger-Strasse 52, 67663, Kaiserslautern, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Gerhards
authors.affiliation: Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany. heske@kit.edu, heske@unlv.nevada.edu.|Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology, Engesserstrasse 18/20, 76128, Karlsruhe, Germany. heske@kit.edu, heske@unlv.nevada.edu.|Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), 4505 Maryland Pkwy, Las Vegas, NV, 89154-4003, USA. heske@kit.edu, heske@unlv.nevada.edu.
authors.forename: Clemens
authors.initials: C
authors.lastname: Heske
authors.affiliation: Institute of Toxicology and Genetics and Institute of Organic Chemistry, Karlsruhe Institute of Technology, Kaiserstrasse 12, 76131, Karlsruhe, Germany. braese@kit.edu.
authors.forename: Stefan
authors.identifier: http://orcid.org/0000-0003-4845-3191
authors.initials: S
authors.lastname: Bräse
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Baumann
authors.affiliation: CYNORA GmbH, Werner-von-Siemensstrasse 2-6, 76646, Bruchsal, Germany. volz@cynora.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Volz
keywords: X-ray absorption spectroscopy; copper; organic light-emitting diodes (OLEDs); thermally activated delayed fluorescence (TADF)