1. Innovative Centre
for Flexible Devices, School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2. School of Electronics Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China
3. Institute of Chemical and Engineering Sciences, 1 Pesek Road, Jurong Island, Singapore 627833, Singapore