Raman antenna effect from exciton-phonon coupling in organic semiconducting nanobelts
Wang, Mao (Norwegian University of Science and Technology)
Gong, Yi (Norwegian University of Science and Technology)
Alzina, Francesc (Institut Català de Nanociència i Nanotecnologia)
Svoboda, Ondrej (Brno University of Technology)
Ballesteros, Belén (Institut Català de Nanociència i Nanotecnologia)
Sotomayor Torres, Clivia M. (Institut Català de Nanociència i Nanotecnologia)
Xiao, Senbo (Norwegian University of Science and Technology)
Zhang, Zhiliang (Norwegian University of Science and Technology)
He, Jianying (Norwegian University of Science and Technology)

Data:	2017
Resum:	The highly anisotropic interactions in organic semiconductors together with the soft character of organic materials lead to strong coupling between nuclear vibrations and exciton dynamics, which potentially results in anomalous electrical, optical and optoelectrical properties. Here, we report on the Raman antenna effect from organic semiconducting nanobelts 6,13-dichloropentacene (DCP), resulting from the coupling of molecular excitons and intramolecular phonons. The highly ordered crystalline structure in DCP nanobelts enables the precise polarization-resolved spectroscopic measurement. The angle-dependent Raman spectroscopy under resonant excitation shows that all Raman modes from the skeletal vibrations of DCP molecule act like a nearly perfect dipole antenna I ∝ cos(θ - 90), with almost zero (maximum) Raman scattering parallel (perpendicular) to the nanobelt's long-axis. The Raman antenna effect in DCP nanobelt is originated from the coupling between molecular skeletal vibrations and intramolecular exciton and the confinement of intermolecular excitons. It dramatically enhances the Raman polarization ratio (ρ =I/I > 25) and amplifies the anisotropy of the angle-dependent Raman scattering (κ = I/I > 12) of DCP nanobelts. These findings have crucial implications for fundamental understanding on the exciton-phonon coupling and its effects on the optical properties of organic semiconductors.
Ajuts:	Ministerio de Economía y Competitividad SEV-2013-0295
Drets:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Anisotropic interaction ; Crystalline structure ; Exciton-phonon couplings ; Intramolecular phonons ; Optoelectrical properties ; Polarization ratios ; Resonant excitation ; Spectroscopic measurements
Publicat a:	Nanoscale, Vol. 9, Issue 48 (December 2017) , p. 19328-19336, ISSN 2040-3372

DOI: 10.1039/c7nr07212k

Preprint 30 p, 1.1 MB

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