1. Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB) Universitat de Barcelona Martí i Franquès 1 08028 Barcelona Spain
2. Department of Chemistry Faculty of Science National University of Singapore 3 Science Drive 3 Singapore 117543 Singapore
3. Solar Energy Research Institute of Singapore (SERIS) National University of Singapore (NUS) 7 Engineering Drive 1, Building E3A, #06-01 Singapore 117574 Singapore
4. Institute of Materials Research and Engineering Agency for Science, Technology and Research (A*STAR) 2 Fusionopolis Way, Innovis Singapore 138634 Singapore