title: High-performance light-emitting diodes based on carbene-metal-amides.
abstract: Organic light-emitting diodes (OLEDs) promise highly efficient lighting and display technologies. We introduce a new class of linear donor-bridge-acceptor light-emitting molecules, which enable solution-processed OLEDs with near-100% internal quantum efficiency at high brightness. Key to this performance is their rapid and efficient utilization of triplet states. Using time-resolved spectroscopy, we establish that luminescence via triplets occurs within 350 nanoseconds at ambient temperature, after reverse intersystem crossing to singlets. We find that molecular geometries exist at which the singlet-triplet energy gap (exchange energy) is close to zero, so that rapid interconversion is possible. Calculations indicate that exchange energy is tuned by relative rotation of the donor and acceptor moieties about the bridge. Unlike other systems with low exchange energy, substantial oscillator strength is sustained at the singlet-triplet degeneracy point.
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Dawei
authors.identifier: 0000-0003-0703-2809
authors.initials: D
authors.lastname: Di
authors.affiliation: School of Chemistry, University of East Anglia, Earlham Road, Norwich NR4 7TJ, UK.
authors.forename: Alexander S
authors.identifier: 0000-0003-2617-6402
authors.initials: AS
authors.lastname: Romanov
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Le
authors.identifier: 0000-0002-3697-171X
authors.initials: L
authors.lastname: Yang
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Richter
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Jasmine P H
authors.identifier: 0000-0001-9396-8667
authors.initials: JP
authors.lastname: Rivett
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Saul
authors.identifier: 0000-0001-6007-2530
authors.initials: S
authors.lastname: Jones
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Tudor H
authors.initials: TH
authors.lastname: Thomas
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Mojtaba
authors.identifier: 0000-0002-9430-6371
authors.initials: M
authors.lastname: Abdi Jalebi
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK.
authors.forename: Richard H
authors.identifier: 0000-0001-6565-6308
authors.initials: RH
authors.lastname: Friend
authors.affiliation: Department of Chemistry, University of Eastern Finland, Joensuu Campus, FI-80101 Joensuu, Finland. mikko.linnolahti@uef.fi m.bochmann@uea.ac.uk djnc3@cam.ac.uk.
authors.forename: Mikko
authors.identifier: 0000-0003-0056-2698
authors.initials: M
authors.lastname: Linnolahti
authors.affiliation: School of Chemistry, University of East Anglia, Earlham Road, Norwich NR4 7TJ, UK. mikko.linnolahti@uef.fi m.bochmann@uea.ac.uk djnc3@cam.ac.uk.
authors.forename: Manfred
authors.identifier: 0000-0001-7736-5428
authors.initials: M
authors.lastname: Bochmann
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK. mikko.linnolahti@uef.fi m.bochmann@uea.ac.uk djnc3@cam.ac.uk.
authors.forename: Dan
authors.identifier: 0000-0003-4246-2118
authors.initials: D
authors.lastname: Credgington