TY - JOUR
T1 - Mobility versus Alignment of a Semiconducting π-Extended Discotic Liquid-Crystalline Triindole
AU - Ruiz, Constanza
AU - Pandey, Upendra K.
AU - Termine, Roberto
AU - García-Frutos, Eva M.
AU - López-Espejo, Guzmán
AU - Ortiz, Rocío Ponce
AU - Huang, Wei
AU - Marks, Tobin J.
AU - Facchetti, Antonio
AU - Ruiz Delgado, M. Carmen
AU - Golemme, Attilio
AU - Gómez-Lor, Berta
N1 - Funding Information:
This work was funded by the Spanish Government MINECO CTQ2013-40562-R grants and the Comunidad de Madrid S2013/MIT-2740 (PHAMA-2.0). A.G. thanks the ELIOTROPO project (PON03PE-00092-2) for support. R.T. was supported by MIUR under the PRIN 2012JHFYMC project. The work at the University of Malaga was supported by MINECO (project reference CTQ2015-66897) and Junta de Andalucia (P09-FQM-4708). M.C.R.D. and R.P.O. thank the MICINN for a Ramon y Cajal Research contract. We acknowledge stimulating discussions related with the chargetransport properties with Professor Gjergji Sini
PY - 2016/10/12
Y1 - 2016/10/12
N2 - 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.
AB - 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.
KW - OFETS
KW - SCLC measurements
KW - discotic liquid-crystals
KW - hole mobility
KW - organic semiconductors
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U2 - 10.1021/acsami.6b06241
DO - 10.1021/acsami.6b06241
M3 - Article
AN - SCOPUS:84991290256
VL - 8
SP - 26964
EP - 26971
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 40
ER -