1. National Center for Nanoscience and Technology Beijing 100190 P.R. China
2. Instituto de Ciencia Molecular Universidad de Valencia Valencia 46022 Spain
3. Michael Grätzel Center for Mesoscopic Solar Cells Huazhong University of Science and Technology Wuhan 430074 P.R. China
4. Department of Mechanical and Materials Engineering University of Nebraska‐Lincoln Lincoln NE 68588 USA
5. Department of Materials and Interfaces Weizmann Institute of Science Rehovot 76100 Israel