N-type organic thin-film transistors based on N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide have been fabricated by thermal evaporation at different substrate temperatures. The best device was obtained at 120 degrees C with a field-effect mobility of 0.12 cm(2)/V.s and threshold voltage around 46 V. In this work, the microstructure of the films is correlated with the device performance. In particular, the dependence of the activation energy for the channel conductance on gate voltages has been related to the properties of the layers. (C) 2009 Elsevier B.V. All rights reserved.