1. Department of Materials Science and EngineeringShenzhen Key Laboratory of Full Spectral Solar Electricity Generation (FSSEG)Southern University of Science and Technology No. 1088, Xueyuan Rd. Shenzhen 518055 Guangdong P. R. China
2. Department of PhysicsThe University of Hong Kong Pokfulam Hong Kong SAR
3. Department of Electrical and Electronic EngineeringSouthern University of Science and Technology No. 1088, Xueyuan Rd. Shenzhen 518055 Guangdong P. R. China
4. Research Institute for Natural SciencesDepartment of ChemistryKorea University Seoul 02841 South Korea