1. Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices under Special Environments, Chinese Academy of Sciences, Xinjiang Key Laboratory of Electronic Information Materials and Devices, 40‐1 South Beijing Road, Urumqi 830011, China, Fax: +86‐991‐3838957, http://www.oefm.cn/
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston IL 60208‐3113, USA