We demonstrate full-color reflection with first- and second-order Bragg reflections in a GO dispersion, and we use two fundamental approaches to manipulate GO photonic crystals, namely, bottom-up and top-down manipulation by controlling the Debye length and using shear or surface fields, respectively. Direct observation of the GO alignments using confocal microscopy reveals excellent layer-to-layer packing assembly and poor in-layer assembly, elucidating the nematic nature of GO rather than its lamellar mesophase. In addition, modulations of the local GO density and alignment enable us to demonstrate full-range color paintings, including chromatic and achromatic colors.
- Tian-Zi Shen
- Seung-Ho Hong
- Jang-Kun Song
