1. Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea, LG Electronics Incorporated, Kumi, Kyungbuk, 730-030, Korea, Department of Materials Science and Engineering Gwangju Institute of Science and Technology, Gwangju 500-712, Korea, and Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106-5096