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Title: Virtually pure near-infrared electroluminescence from exciplexes at polyfluorene/hexaazatrinaphthylene interfaces

Electronic processes at the heterojunction between chemically different organic semiconductors are of special significance for devices such as light-emitting diodes (LEDs) and photovoltaic diodes. Here, we report the formation of an exciplex state at the heterojunction of an electron-transporting material, a functionalized hexaazatrinaphthylene, and a hole-transporting material, poly(9,9-dioctylfluorene-alt-N-(4-butylphenyl)diphenylamine) (TFB). The energetics of the exciplex state leads to a spectral shift of ∼1 eV between the exciton and the exciplex peak energies (at 2.58 eV and 1.58 eV, respectively). LEDs incorporating such bulk heterojunctions display complete quenching of the exciton luminescence, and a nearly pure near-infrared electroluminescence arising from the exciplex (at ∼1.52 eV) with >98% of the emission at wavelengths above 700 nm at any operational voltage.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5]
  1. Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, London WC1E 6BT (United Kingdom)
  2. School of Soft Matter Research, Freiburg Institute for Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstraße 19, 79104 Freiburg (Germany)
  3. (Germany)
  4. POLYMAT, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, E-20018 Donostia-San Sebastian (Spain)
  5. (Spain)
Publication Date:
OSTI Identifier:
22350863
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 14; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ELECTRIC POTENTIAL; ELECTROLUMINESCENCE; EQUIPMENT; EV RANGE; HETEROJUNCTIONS; HOLES; INTERFACES; LIGHT EMITTING DIODES; ORGANIC SEMICONDUCTORS; PHOTOVOLTAIC EFFECT; SPECTRAL SHIFT; WAVELENGTHS