1. School
of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
2. Group
for Molecular Engineering of Functional Materials, EPFL Valais Wallis, CH-1951 Sion, Switzerland
3. Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China
4. Interdisciplinary
Centre for Electron Microscopy, EPFL, CH-1015 Lausanne, Switzerland
5. Photovoltaics
and Thin Films Electronics Laboratory, EPFL Neuchâtel, CH-2002 Neuchâtel, Switzerland