1. Department of Materials Science and Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices, Southern University of Science and Technology, Shenzhen, 518055 Guangdong, P. R. China
2. Department of Mechanical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, 999077 Hong Kong, P. R. China