1. Institut für Angewandte Photovoltaik, Munscheidstrasse 14, D-45886 Gelsenkirchen, Germany, Department of Chemistry, University of Peradeniya, Sri Lanka, School of Chemistry, University of Bath, Bath BA2 7AY, U.K., and Laboratoire de Physique des Solides de Bellevue, CNRS, UPR 1332, 1 Place Aristide Briand, 92195 Meudon, France