1. Center for Advanced Photovoltaics Department of Electrical Engineering and Computer Sciences South Dakota State University Brookings SD 57007 USA
2. Sichuan Research Center of New Materials Institute of Chemical Materials China Academy of Engineering Physics Chengdu 610207 China
3. Hefei National Laboratory for Physical Sciences at Microscale Department of Materials Science and Engineering University of Science and Technology of China 96 Jinzhai Road Hefei Anhui 230026 China
4. Electrochemistry Branch Sensor and Electron Devices Directorate Power and Energy Division U.S. Army Research Laboratory Adelphi MD 20783 USA
5. Mechanical and Aerospace Engineering Syracuse University Syracuse NY 13244 USA