1. Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
2. Holst Centre/TNO, High Tech Campus 31, 5656 AE Eindhoven, The Netherlands
3. Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom
4. Cambridge Display Technology Ltd., Cambourne Business Park, Cambridgeshire CB23 6DW, United Kingdom
5. Department of Materials Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea