Development of nano-porous photo-catalysis with opal and inverse opal structure

近年来，由晶格参数与可见光波长相当的空间有序光子晶体构成的光子晶体由于其在控制光的传播方面的独特性质而受到广泛关注。即使是那些没有表现出完整光子带隙的晶体仍然可以显示出有趣的光学性质，例如也可以作为结构色观察到的光学阻带。对于许多实际应用来说，能够通过外部激励来控制光子带结构是重要的。沿着这条路线，我们通过将光敏液晶渗透到反蛋白石结构薄膜中，制备了可调光子带隙晶体。通过液晶的光致相变可以实现对它们光学性质的调控。光诱导相变行为可以通过测量它们在光照射下的光学性质的变化来评估，并且可以清楚地观察到该行为随温度和光强度而变化。该材料可以存储和显示由LTV光通过光掩模照射产生的图像。这种技术的一个很大的优点是，膜本身可以显示图像，而不使用偏振器或其他辅助材料，并且它们还可以呈现可以通过改变反蛋白石结构的晶格距离来选择的颜色显示。此外，我们实现了通过施加电场来控制它们的光学性质。由于电场诱导的状态与光诱导相变所产生的状态不同，因此现在可以通过这两种技术的组合在三种状态之间切换。我们开发的材料在光学器件中具有实际应用的可能性。

Recently, photonic crystals (PCs) composed of spatially ordered dielectrics with lattice parameters comparable to the wavelength of visible light have received much attention due to their unique properties in controlling the propagation of light. Even those crystals that do not exhibit a complete photonic band gap can still show interesting optical properties, such as an optical stop band that can also be observed as a structural color. It is important to be able to control the photonic band structure through external stimuli for many practical applications. Along this line we prepared tunable photonic band gap crystals by infiltrating photoresponsive liquid crystals into inverse opal structure films. The tuning of their optical properties could be realized by means of photoinduced phase transition of liquid crystals. The photoinduced phase transition behavior could be evaluated by measuring the change in their optical properties under light irradiation, and it was clearly observed that the behavior varied with temperature and light intensity. The materials could store and display images that were created by the irradiation with LTV light through a photomask. A great advantage of this technique is that the films themselves can display an image without the use of polarizers or other assistant materials, and they can also render a color display that can be selected by varying the lattice distance of the inverse opal structure. In addition, we achieved the control of their optical properties by the application of an electric field. Because the state induced by the electric field is different from that engendered by a photoinduced phase transition, it is now possible to switch among three states by a combination of these two techniques. The materials that we have developed have possibilities for practical applications in optical devices.