Structural, Spectroscopic, and Computational Characterization of the Concomitant Polymorphs of the Natural Semiconductor Indigo

T. Salzillo, S. D'Agostino, A. Rivalta, A. Giunchi, A. Brillante, R. G. Della Valle, N. Bedoya-Martínez, E. Zojer, F. Grepioni, E. Venuti

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Indigo [2,2′-bis(2,3-dihydro-3-oxoindolyliden)], a commonly used natural dye, has been shown to exhibit a highly promising semiconducting behavior, allowing for the realization of ambipolar devices. Nevertheless, up to date, it is still unclear which crystal structure is present in the thin films, a piece of information relevant for device applications. In this work, we address this issue by an in-depth characterization of the polymorphs of Indigo in the bulk and in drop-cast films. To do this, X-ray diffraction (XRD) and micro-Raman spectroscopy have been employed jointly, with the support of state-of-the-art density functional theory calculations in the solid state. Structural and spectroscopic characterizations have established that the two known A and B polymorphs grow as concomitant in the bulk under most of the experimental conditions adopted in this work. In the drop-cast films, XRD cannot unambiguously identify the structure, but Raman spectroscopy is effective in establishing that only the B form is present. The calculations augment the experiments, providing valuable insights into the relative thermodynamic stability of the two forms as a function of temperature. They also allow for a more comprehensive characterization of the Raman modes.

Original languageEnglish
Pages (from-to)18422-18431
Number of pages10
JournalJournal of Physical Chemistry C
Volume122
Issue number32
DOIs
Publication statusPublished - 16 Aug 2018

Fingerprint

Indigo Carmine
Polymorphism
Semiconductor materials
Raman spectroscopy
casts
X ray diffraction
diffraction
Density functional theory
Thermodynamic stability
x rays
Coloring Agents
Dyes
Crystal structure
dyes
density functional theory
solid state
Thin films
thermodynamics
crystal structure
thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Fields of Expertise

  • Advanced Materials Science

Cite this

Salzillo, T., D'Agostino, S., Rivalta, A., Giunchi, A., Brillante, A., Della Valle, R. G., ... Venuti, E. (2018). Structural, Spectroscopic, and Computational Characterization of the Concomitant Polymorphs of the Natural Semiconductor Indigo. Journal of Physical Chemistry C, 122(32), 18422-18431. https://doi.org/10.1021/acs.jpcc.8b03635

Structural, Spectroscopic, and Computational Characterization of the Concomitant Polymorphs of the Natural Semiconductor Indigo. / Salzillo, T.; D'Agostino, S.; Rivalta, A.; Giunchi, A.; Brillante, A.; Della Valle, R. G.; Bedoya-Martínez, N.; Zojer, E.; Grepioni, F.; Venuti, E.

In: Journal of Physical Chemistry C, Vol. 122, No. 32, 16.08.2018, p. 18422-18431.

Research output: Contribution to journalArticleResearchpeer-review

Salzillo, T, D'Agostino, S, Rivalta, A, Giunchi, A, Brillante, A, Della Valle, RG, Bedoya-Martínez, N, Zojer, E, Grepioni, F & Venuti, E 2018, 'Structural, Spectroscopic, and Computational Characterization of the Concomitant Polymorphs of the Natural Semiconductor Indigo' Journal of Physical Chemistry C, vol. 122, no. 32, pp. 18422-18431. https://doi.org/10.1021/acs.jpcc.8b03635
Salzillo, T. ; D'Agostino, S. ; Rivalta, A. ; Giunchi, A. ; Brillante, A. ; Della Valle, R. G. ; Bedoya-Martínez, N. ; Zojer, E. ; Grepioni, F. ; Venuti, E. / Structural, Spectroscopic, and Computational Characterization of the Concomitant Polymorphs of the Natural Semiconductor Indigo. In: Journal of Physical Chemistry C. 2018 ; Vol. 122, No. 32. pp. 18422-18431.
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