El-Jallal Said, Hochedel Marion, Capitolis Jerôme, Nguyen Hai-Son, Chevalier Céline, Leclercq Jean-Louis, Amara Mohamed, Seassal Christian, Drouard Emmanuel
Opt Express. 2022 Aug 1;30(16):29694-29707. doi: 10.1364/OE.461390.
A few tens of nanometre thick ultrathin materials may suffer from a very low absorption at their band edges. In this work, we investigate a photonic crystal (PC) made of a lowcost, transparent patterned silicon nitride (SiN) layer, conformally covered with an ultrathin active layer (e.g., 20 nm TiO) in view of its use in various applications such as photocatalysis. A fair estimation of the absorption enhancement, considering the volume of the active material, is calculated using RCWA. A remarkable enhancement (more than ten-folds) in absorptance in the near UV range and a very high transmittance over the visible range are observed. A detailed modal analysis of the structures-of-interest unravels the Light Trapping (LT) mechanisms and allows the derivation of key design guidelines. Optical measurements on a patterned sample provide a first proof-of-concept of such possible photonic backbone structures suitable for highly efficient depollution and artificial photosynthesis for solar fuels production.
几十纳米厚的超薄材料在其能带边缘可能具有非常低的吸收率。在这项工作中，鉴于其在光催化等各种应用中的用途，我们研究了一种由低成本、透明图案化氮化硅（SiN）层制成的光子晶体（PC），该层共形覆盖有超薄活性层（例如20 nm TiO）。考虑到活性材料的体积，使用严格耦合波分析（RCWA）计算了吸收增强的合理估计值。在近紫外范围内观察到吸收率显著提高（超过十倍），在可见光范围内观察到非常高的透射率。对感兴趣结构的详细模态分析揭示了光捕获（LT）机制，并允许推导关键设计准则。对图案化样品的光学测量提供了这种可能适用于高效去污染和用于太阳能燃料生产的人工光合作用的光子骨架结构的首个概念验证。
