光子晶体光局域效应增强光吸收率应用基础研究

It was found recently that light harvest efficiency could be enhanced significantly by the light localization through photonic crystals (PCs) at the photonic band gap(PBG), opening a new approach to increase the light utilization. However, the fundamentals behind the light-harvesting enhancement is not fully understand, because the research on the topics is just at its beginning and the previous investigators usually use the inverse opal as the PCs, the fabrication of which is complicated and the structure of the inverse opal PCs is hard to reproduced. This project will use the easy-fabrication SiO2 opal film as the PCs and the TiO2-catalyzed oxi-degradation of organic compounds as the probe reaction to investigate the some fundamentals of the light-harvesting enhancement by PCs through the photons localization at the PBG of PCs. The SiO2 opal films will be fabricated through the ordered packing of the monodisperse silica microspheres. The effect of match of the PBG and the UV-Vis adsorption edge of light absorber on the light-harvesting enhancement will be investigated by varying the PBG of the photonic crystals near the UV-Vis adsorption edge of TiO2. By changing the period number of the PCs, we can find out how the strength of light localized by the photonic crystals changes with the period number of the PCs. The space-dependence of the strength of light localized near the photonic crystal edge will be investigated through changing the distance between the PCs and the TiO2 photo catalyst. The project is of significance for the utilization of sun light, clearing up of environment and photo-synthesis.

最近研究发现，利用光子晶体光子带隙频带上的光局域效应可显著增强光吸收，开辟了提高光利用效率的崭新途径。由于这一领域的研究刚刚起步，并且已有相关研究工作都是利用结构参数难以调控的反Opal光子晶体作为实验体系，对光子晶体的光局域增强光吸收效应的原理和规律认识很不足。本项目利用制作重现性高、结构参数易实现单独调控的SiO2 Opal膜作为光子晶体，nc-TiO2膜吸收光催化降解有机物为探针，研究光子晶体的光局域效应增强光吸收率一些基本科学问题。SiO2 Opal光子晶体膜通过单分散SiO2微球有序组装得到。通过调节光子晶体带隙频带、结构周期数和光子晶体膜与nc-TiO2膜间的距离，研究光子晶体的光子带隙与吸光材料UV-Vis吸收边的耦合作用、光子晶体的结构周期数与光局域增强光收率效应的相关性、以及光局域效应在空间的分布。研究工作对于太阳能利用、光降解污染物和光化学合成等具有重大意义。

光子晶体光子带隙频带上的光局域效应可显著增强光吸收，是提高光利用效率的崭新途径。由于这一领域的研究刚刚起步，并且已有相关研究工作都是利用结构参数难以调控的反Opal光子晶体作为实验体系，对光子晶体的光局域增强光吸收效应的原理和规律认识很不足。本项目利用制作重现性高、结构参数易实现单独调控的SiO2 Opal膜作为光子晶体，nc-TiO2膜吸收光催化降解有机物为探针，研究光子晶体的光局域效应增强光吸收率一些基本科学问题。SiO2 Opal光子晶体由单分散SiO2微球的有序组装制备，其光子带隙和结构周期数分别由SiO2微球的直径和组装层数调控。nc-TiO2/SiO2 opal复合催化剂中nc-TiO2层和SiO2 opal层的距离调控通过在两层中嵌入惰性透明的SiO2 space来实现。通过研究得到如下结论。光子晶体的带隙位置与TiO2电子带隙的位置越近，复合膜的催化活性越高（光局域效应越大）。光子晶体的结构周期数越多，光局域效应越大。当结构周期数多于35时，光局域效应不再随结构周期数的增大而增大。光子晶体的光局域效应可以存在于光子晶体外面，离光子晶体越远，光局域效应越小。当光子晶体与nc-TiO2的距离大于2.9um时，光局域效应基本消失。此外，光子带隙与CdS QDs电子带隙重合的SiO2 Opal光子晶体也能显著提高CdS QDs/nc-TiO2复合膜在可见光处的光收率，因而显著提高了其光催化活性。本项目的研究成果，对于太阳能利用、光降解污染物和光化学合成等具有重大意义.