Mobility versus Alignment of a Semiconducting π-Extended Discotic Liquid-Crystalline Triindole

Constanza Ruiz, Upendra K. Pandey, Roberto Termine, Eva M. García-Frutos, Guzmán López-Espejo, Rocío Ponce Ortiz, Wei Huang, Tobin J Marks, Antonio Facchetti, M. Carmen Ruiz Delgado, Attilio Golemme, Berta Gómez-Lor

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18 Citations (Scopus)

Abstract

The p-type semiconducting properties of a triphenylene-fused triindole mesogen, have been studied by applying two complementary methods which have different alignment requirements. The attachment of only three flexible alkyl chains to the nitrogen atoms of this π-extended core is sufficient to induce columnar mesomorphism. High hole mobility values (0.65 cm2 V-1 s-1) have been estimated by space-charge limited current (SCLC) measurements in a diode-like structure which are easily prepared from the melt, rendering this material a good candidate for OPVs and OLEDs devices. The mobility predicted theoretically via a hole-hopping mechanism is in very good agreement with the experimental values determined at the SCLC regime. On the other hand the hole mobility determined on solution processed thin film transistors (OFETs) is significantly lower, which can be rationalized by the high tendency of these large molecules to align on surfaces with their extended π-conjugated core parallel to the substrate as demonstrated by SERS. Despite the differences obtained with the two methods, the acceptable performance found on OFETs fabricated by simple drop-casting processing of such an enlarged aromatic core is remarkable and suggests facile hopping between neighboring molecular columns owing to the large conducting/isolating ratio found in this discotic compound.

Original languageEnglish
Pages (from-to)26964-26971
Number of pages8
JournalACS Applied Materials and Interfaces
Volume8
Issue number40
DOIs
Publication statusPublished - Oct 12 2016

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Keywords

  • discotic liquid-crystals
  • hole mobility
  • OFETS
  • organic semiconductors
  • SCLC measurements

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Ruiz, C., Pandey, U. K., Termine, R., García-Frutos, E. M., López-Espejo, G., Ortiz, R. P., Huang, W., Marks, T. J., Facchetti, A., Ruiz Delgado, M. C., Golemme, A., & Gómez-Lor, B. (2016). Mobility versus Alignment of a Semiconducting π-Extended Discotic Liquid-Crystalline Triindole. ACS Applied Materials and Interfaces, 8(40), 26964-26971. https://doi.org/10.1021/acsami.6b06241