1. National‐Local Joint Engineering Laboratory of New Energy Photovoltaic Devices Key Laboratory of Brain‐Like Neuromorphic Devices and Systems of Hebei Province College of Physics Science and Technology Hebei University Baoding 071002 P. R. China
2. Hebei Key Laboratory of Optic‐Electronic Information Materials College of Physics Science and Technology Hebei University Baoding 071002 P. R. China
3. Department of Materials Science and Engineering National University of Singapore Singapore 117576 Singapore