1. Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
2. Department of Chemistry, Faculty of Science, Beni-Suef University, Salah Salem Str, Beni-Suef 62511, Egypt
3. Lumileds Phosphor Center Aachen, Lumileds (Germany) GmbH, Philipsstraße 8, Aachen 52068 , Germany
4. Department of Chemistry, University of Munich (LMU), Butenandtstraße 5-13, München 81377, Germany