[1] Hong Kong Polytech Univ, Dept Appl Phys, Hong Kong, Peoples R China
[2] Hong Kong Polytech Univ, Res Inst Intelligent Wearable Syst, Hong Kong, Peoples R China
[3] Hong Kong Baptist Univ, Dept Phys, Hong Kong, Peoples R China
[4] Univ Groningen, Zernike Inst Adv Mat, Photophys & OptoElect, Nijenborgh 4, NL-9747 AG Groningen, Netherlands
[5] Univ Stuttgart, Inst Photovolta Ipv, D-70569 Stuttgart, Germany