Fig. 5. Coloring of PS nanoparticles with GQDs. (a) Photographs of PS nanoparticles (192, 214, 274, and 396 nm) at various GQDs-7 weight concentration. Concentration of GQDs additive increases from left to right. The scale bar is 5 mm. (b) Reflectance spectra of PS/GQDs thin film. The PS nanoparticles sizes are 192, 214, 274, and 396 nm. The GQDs-7 concentration is 1 wt%. (c) Photograph of photonic ink writings on different substrates (paper, glass and wafer). (d) Photograph of photonic ink calligraphy of a Chinese Tang dynasty famous poem “On the Stork Tower”.
