1. Materials Science and Nanotechnology Program Department of Physics Faculty of Science Khon Kaen University Khon Kaen 40002 Thailand
2. National Nanotechnology Center (NANOTEC) National Science and Technology Development Agency (NSTDA) 111 Thailand Science Park, Phahonyothin Road, Khlong Nueng, Khlong Luang Pathum Thani 12120 Thailand
3. Institute of Nanomaterials Research and Innovation for Energy (IN‐RIE) Research Network of NANOTEC‐KKU (RNN) Khon Kaen University Khon Kaen 40002 Thailand