https://doi.org/10.1140/epjb/e2008-00409-1
Quantum size effects in the optical properties of organic superlattices containing 3, 4, 9, 10 perylene tetracarboxylic dianhydride (PTCDA)
1
Instituto Universitario de Materiales de Alicante and Dpto. de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, 03080 Alicante, Spain
2
Institute of Physics, Faculty of Sciences, University of Novi Sad, Trg D. Obradovića 4, 21000 Novi Sad, Serbia
3
Walter Schottky Institut, Technische Universität München, 85748 Garching, Germany
Corresponding author: a igor.vragovic@ua.es
Received:
4
August
2008
Published online:
8
November
2008
A Frenkel exciton model is applied to ultrathin films of PTCDA confined between layers of a material with electronic transitions in a different energetic region. This model accounts for the elongation of an effective internal vibration in the relaxed excited geometry of a molecule and for the transfer of an electronic excitation between different molecular sites. The comparison of the model calculations with experimental findings reveals that due to the modified conditions at the organic interfaces, boundary layers of the PTCDA films show blue-shifted transition energies with respect to inner molecular layers surrounded by the same material. The resulting changes of the lowest vibronic subband contribute further to the distinct absorption line shapes.
PACS: 71.35.Aa – Frenkel excitons and self-trapped excitons / 33.20.-t – Molecular spectra / 78.20.Bh – Theory, models, and numerical simulation / 78.55.Kz – Solid organic materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008
