1. Centre of Electronic Optoelectronics and Telecommunications Universidade do Algarve Campus de Gambelas 8000 Faro (Portugal);2. Philips Research Laboratories High Tech Campus 4 5656 AE Eindhoven (The Netherlands);3. University of Groningen Zernike Institute of Advanced Materials Nijenborgh 4 9747 AG Groningen (The Netherlands);4. Dutch Polymer Institute (DPI) P.O. Box 902 5600 AX Eindhoven (The Netherlands)