1. Department of Materials Science & Engineering National University of Singapore Singapore 117575 Singapore
2. Key Laboratory of Brain‐like Neuromorphic Devices and Systems of Hebei Province Key Laboratory of Optoelectronic Information Materials of Hebei Province Hebei University Baoding Hebei 071002 China
3. Department of Chemistry National University of Singapore Singapore 117543 Singapore
4. Suzhou Research Institute National University of Singapore Suzhou 215123 China