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1594551 
Journal Article 
Crystal structure and charge-transport properties of N-trimethyltriindole: Novel p-type organic semiconductor single crystals 
Garcia-Frutos, EvaM; Gutierrez-Puebla, E; Angeles Monge, M; Ramirez, R; de Andres, P; de Andres, A; Ramirez, R; Gomez-Lor, B 
2009 
1 
Organic Electronics
ISSN: 1566-1199 
10 
4 
643-652 
WOS:000267335800013 
We report on a new p-type organic semiconductor single
crystal, 5,10,15-trimethyl-10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole (N-
trimethyltriindole). This molecule crystallizes forming a highly ordered columnar structure in
which stacked molecules are situated at two alternating distances (3.53 angstrom and 3.68
angstrom) along the column as determined by single crystal X-ray diffraction analysis. These
short intermolecular distances between adjacent units, make this system an ideal candidate for
charge-transport processes along the stacks. Relevant parameters for transport (i.e. internal
reorganization energies, transfer integral) have been estimated by DFT calculations at a 6-311 G
(d,p)/B3LYP level of theory. As a double check for the transfer integral, the electronic band
structure of a one-dimensional stack of molecules has been computed. The electronic properties of
this material have been studied both theoretically and experimentally. Its HOMO value is found to
coincide with Au work function (Phi(Au) = 5.1 eV), thus low barriers are expected for hole
injection from gold electrodes. The hole mobility of this material has been predicted
theoretically considering a hopping-type mechanism for the charge-transport and determined
experimentally at the space charge limited current (SCLC) regime of the current-voltage
measurements. Both theoretical and experimental values are in good agreement. The high hole
mobility (mu(min) = 0.4 cm(2) V(-1) s(-1)) of this material points towards its useful application
in the organic electronics arena. N-Trimethyltriindole single crystals constitute an essential
model to study transport properties of triindole-based materials and to design new derivatives
with improved electronic performance. (C) 2009 Elsevier B.V. All rights reserved. 
Hole transport; Organic semiconductor; Single crystals