title: Mobility versus Alignment of a Semiconducting π-Extended Discotic Liquid-Crystalline Triindole.
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 cm2V-1s-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.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC , Cantoblanco, 28049, Madrid, Spain.|Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Constanza
authors.initials: C
authors.lastname: Ruiz
authors.affiliation: LASCAMM CR-INSTM, CNR-NANOTEC Lab LiCryL, Dipartimento di Fisica, Università della Calabria , 87036 Rende, Italy.|Interdisciplinary Centre for Energy Research, Indian Institute of Science , Bangalore, 560012, India.
authors.forename: Upendra K
authors.initials: UK
authors.lastname: Pandey
authors.affiliation: LASCAMM CR-INSTM, CNR-NANOTEC Lab LiCryL, Dipartimento di Fisica, Università della Calabria , 87036 Rende, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Termine
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC , Cantoblanco, 28049, Madrid, Spain.
authors.forename: Eva M
authors.initials: EM
authors.lastname: García-Frutos
authors.affiliation: Department of Physical Chemistry, University of Málaga , 29071, Málaga, Spain.
authors.forename: Guzmán
authors.initials: G
authors.lastname: López-Espejo
authors.affiliation: Department of Physical Chemistry, University of Málaga , 29071, Málaga, Spain.
authors.forename: Rocío Ponce
authors.initials: RP
authors.lastname: Ortiz
authors.affiliation: Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.affiliation: Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
authors.affiliation: Department of Chemistry and the Materials Research Center, the Argonne-Northwestern Solar Energy Research Center, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208, United States.
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchetti
authors.affiliation: Department of Physical Chemistry, University of Málaga , 29071, Málaga, Spain.
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Ruiz Delgado
authors.affiliation: LASCAMM CR-INSTM, CNR-NANOTEC Lab LiCryL, Dipartimento di Fisica, Università della Calabria , 87036 Rende, Italy.
authors.forename: Attilio
authors.initials: A
authors.lastname: Golemme
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC , Cantoblanco, 28049, Madrid, Spain.
authors.forename: Berta
authors.initials: B
authors.lastname: Gómez-Lor
keywords: OFETS; SCLC measurements; discotic liquid-crystals; hole mobility; organic semiconductors