* Corresponding authors

^a Department of Chemistry, Science of Advanced Materials Doctoral Program, Central Michigan University, 201 E Ottawa Ct. Dow 350, Mount Pleasant, MI 48859, USA
E-mail: li3b@cmich.edu
Fax: +1-989-774-3883
Tel: +1-989-774-3441

^b Department of Physics, Science of Advanced Materials Doctoral Program, Central Michigan University, Mount Pleasant, MI 48859, USA

^c Research Laboratory for Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

^d Department of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA

^e Department of Applied Physics, Shandong Agricultural University, Shandong, China