1. Department of Electrical Engineering and Computer ScienceCenter for Advanced Photovoltaics and Sustainable EnergySouth Dakota State University Brookings SD 57007 USA
2. School of Science and Key Lab of Optoelectronic Materials and DevicesHuzhou University Huzhou Zhejiang Province 313000 P. R. China
3. Sichuan Research Center of New MaterialsInstitute of Chemical MaterialsChina Academy of Engineering Physics Chengdu Sichuan 610207 P. R. China