1. State Key Laboratory of Photoelectric Technology and Functional Materials International Collaborative Center on Photoelectric Technology and Nano Functional Materials Institute of Photonics & Photon‐Technology Northwest University Xi'an 710069 China
2. National‐Local Joint Engineering Laboratory of New Energy Photoelectric Devices Hebei Key Laboratory of Optic‐electronic Information and Materials College of Physics Science & Technology Hebei University Baoding 071002 China