1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources Beijing Key Laboratory of Energy Safety and Clean Utilization North China Electric Power University Beijing 102206 P. R. China
2. Imec, Imo‐imomec, Thin Film PV Technology EnergyVille, Thor Park 8320 Genk 3600 Belgium
3. Hasselt University, imo‐imomec Martelarenlaan 42 Hasselt 3500 Belgium
4. State Key Laboratory of Photovoltaic Science and Technology Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception Institute of Optoelectronics Department of Materials Science Fudan University Shanghai 200433 P. R. China