Univ Sao Paulo, Inst Fis Sao Paulo, BR-13560970 Sao Carlos, SP - Brazil
 Univ Bordeaux, Ctr Rech Paul Pascal, F-33600 Pessac - France
 CNRS, F-33600 Pessac - France
Total Affiliations: 5
ACS APPLIED MATERIALS & INTERFACES;
NOV 27 2013.
Web of Science Citations:
Discotic molecules comprising a rigid aromatic core and flexible side chains have been promisingly applied in OLEDs as self-organizing organic semiconductors. Due to their potentially high charge carrier mobility along the columns, device performance can be readily improved by proper alignment of columns throughout the bulk. In the present work, the charge mobility was increased by 5 orders of magnitude due to homeotropic columnar ordering induced by the boundary interfaces during thermal annealing in the mesophase. State-of-the-art diodes were fabricated using spin-coated films whose homeotropic alignment with formation of hexagonal germs was observed by polarizing optical microscopy. The photophysical properties showed drastic changes at the mesophase-isotropic transition, which is supported by the gain of order observed by X-ray diffraction. The electrical properties were investigated by modeling the current-voltage characteristics by a space-charge-limited current transport with a field dependent mobility. (AU)