1. WCU Hybrid Materials Program; Department of Materials Science and Engineering and the Center for Organic Light Emitting Diode; Seoul National University; Seoul 151-742 South Korea
2. Department of Chemistry and Low Carbon Energy Research Center; National Tsing Hua University; Hsinchu 30013 Taiwan
3. Department of Organic Material Science and Engineering; Pusan National University; Busan 609-755 Korea
4. Instrumentation Center; National Taiwan University; Taipei 10617 Taiwan