1. Department of Materials, University of Oxford, Oxford OX1 3PH, United Kingdom
2. Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634
3. Department of Chemistry, National University of Singapore, Singapore 117543
4. Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
5. Biological and Biomimetic Material Laboratory, Center for Biomimetic Sensor Science, School of Materials Science and Engineering, Nanyang Technological University (NTU), Singapore 637553
6. Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
7. Hybrid Materials for Optoelectronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, The Netherlands