We have purified oligomer semiconductors through vacuum sublimation and compared the film morphologies and the device performance of the purified materials with those of unpurified ones. We fabricated melt-molding films and thin film organic field-effect transistors (OFETs) using both the purified and unpurified oligomers. Comparing morphologies of the molten films we found regular arrangements of the crystal domains for the purified oligomers. Furthermore, the purified materials show definite light emission from the OFET devices. (C) 2009 Elsevier B.V. All rights reserved.