We fabricated copper phthalocyanine (CuPc) thin-film field-effect transistors (FETs) on a rubbed flexible polyethersulfone (PES) substrate. Rubbing the PES film induced a unidirectional orientation of CuPc crystallites, which were oriented perpendicular to the rubbing direction. Favorable conditions for fabricating a CuPc FET were determined after fabricating CuPc FETs of two different types and evaluating their output performance. Well-aligned CuPc crystallites along the direction connecting source and drain electrodes can play an important role in improving the output performance of the fabricated FETs. (C) 2010 Elsevier B.V. All rights reserved.