Tuning the Structural Color of a 2D Photonic Crystal Using a Bowl-like Nanostructure

Abstract

Structural colors of the ordered photonic nanostructures are widely used as an effective platform for manipulating the propagation of light. Although several approaches have been explored in attempts to mimic the structural colors, improving the reproducibility, mechanical stability, and the economic feasibility of sophisticated photonic crystals prepared by complicated processes continues to pose a challenge. In this study, we report on an alternative, simple method for fabricating a tunable photonic crystal at room temperature. A bowl-like nanostructure of TiO2 was periodically arranged on a thin Ti sheet through a two-step anodization process where its diameters were systemically controlled by changing the applied voltage. Consequently, they displayed a broad color distribution, ranging from red to indigo, and the principal reason for color generation followed the Bragg diffraction theory. This noncolorant method was capable of reproducing a Mondrian painting on a centimeter scale without the need to employ complex architectures, where the generated structural colors were highly stable under mechanical or chemical influence. Such a color printing technique represents a potentially promising platform for practical applications for anticounterfeit trademarks, wearable sensors, and displays.

3D Hierarchical Nanorod@Nanobowl Array Photoanode with a Tunable Light‐Trapping Cutoff and Bottom‐Selective Field Enhancement for Efficient Solar Water Splitting

“…The absorption of Fe 2 O 3 NB is much higher than that of the planar structure, and the absorption band edges is 600 nm (close to the planar one), 615 nm, and 630 nm, respectively (more detail in Figure S4, Supporting Information), which showed similar trend to simulated results and also was accorded with the previous nanobowl arrays structure made of other material such as Si and TiO 2 applied in the Structural Color . The absorption edge shift as the diameter increasing can be explained by light diffraction and refraction theories . The absorption enhancement is attributed to the light‐trapping effect of 3D nanobowl array .…”

“…The optical properties of the Fe 2 O 3 NB photoanode with diameter of 0.5, 0.8, and 1.0 µm were measured by UV–vis spectroscopy, and presented in the form of the efficiencies of light harvesting (LHE) in Figure b. The absorption of Fe 2 O 3 NB is much higher than that of the planar structure, and the absorption band edges is 600 nm (close to the planar one), 615 nm, and 630 nm, respectively (more detail in Figure S4, Supporting Information), which showed similar trend to simulated results and also was accorded with the previous nanobowl arrays structure made of other material such as Si and TiO 2 applied in the Structural Color . The absorption edge shift as the diameter increasing can be explained by light diffraction and refraction theories .…”

Observation of crystalline changes of titanium dioxide during lithium insertion by visible spectrum analysis

“…Here, we used a simple anodization method established in our previous research (see the Experimental section), to fabricate a complex TiO 2 polymorph-deposited surface with a precisely arranged nanostructure. 15 The TiO 2 deposited surface had uniform nanoscale hexagonal pores (the structure detail is shown in Fig. 1(a) and (b)) that induced a distinguishable wave interference and a structural color (inset of Fig.…”

“…15 A two-electrode cell, using Ti foil (Sigma-Aldrich) as a working electrode and a Pt mesh as a counter electrode, was utilized. The back of the Ti foil was protected by an electrically inactive tape to allow it to function as a current collector.…”

Self-organized and self-assembled TiO2 nanosheets and nanobowls on TiO2 nanocavities by electrochemical anodization and their properties

“…Recently, Umh et al showed that TiO 2 nanobowls can be used as photonic crystals. They reported that TiO 2 nanostructures had two bands of reflection and can be modified with increasing of the cavity diameter of nanobowls by modifying the voltage of anodization [18].…”