Direct evidence of the temperature-induced molecular re-orientation in tetracene thin films on AlOx/Ni3Al(111)

  • chair:

    Naboka, M. / Soubatch, S. / Nefedov, A. / Tautz, S. / Wöll, C. (2014)
  • place:

    J. Phys. Chem. C . 118 (2014), 39, 22678-22682
  • Date: 2014

  • Naboka, M. / Soubatch, S. / Nefedov, A. / Tautz, S. / Wöll, C. (2014): „Direct evidence of the temperature-induced molecular re-orientation in tetracene thin films on AlOx/Ni3Al(111)“. In: J. Phys. Chem. C . 118 (2014), 39, 22678-22682

Abstract

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Control over the optical properties of the fluorescent organic layer plays a key role in the development of organic light-emitting diodes. A combination of near-edge X-ray absorption fine structure spectroscopy and X-ray photoelectron spectroscopy was used to study structural changes in thin films of tetracene on AlOx/Ni3Al(111).

It is shown that upon deposition onto the cold (100 K) substrate, a monolayer of tetracene molecules adopts a disordered adsorption configuration with the molecular planes orientated almost parallel to the surface. Upon annealing at 280 K, the molecular packing changes and the tetracene units adopt a more upright orientation.

The consequences of this orientational change for the luminescent properties of the molecular adlayer are discussed, in particular with regard to a quenching of the optical excitation by an electronic coupling of occupied and unoccupied molecular states to those of the metal substrate.