1. Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab of Information Photonic Technique School of Electronic and Information Engineering Xi'an Jiaotong University No.28, Xianning West Road Xi'an 710049 China
2. Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan 030006 China
3. Department of Materials Science and Engineering, and Argonne‐Northwestern Solar Energy Research (ANSER) Center Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
4. Mitsubishi Chemical Group Science & Technology Research Center Inc., 1000 Kamoshida‐cho Aoba‐ku Yokohama 227‐8502 Japan