Raad Shiva Hayati, Atlasbaf Zahra
Department of Electrical and Computer Engineering, Tarbiat Modares University, Tehran, Iran.
Sci Rep. 2021 Aug 9;11(1):16169. doi: 10.1038/s41598-021-95684-2.
In this paper, the full solar spectrum coverage with an absorption efficiency above 96% is attained by shell-shaped graphene-based hollow nano-pillars on top of the refractory metal substrate. The material choice guarantees the high thermal stability of the device along with its robustness against harsh environmental conditions. To design the structure, constitutive parameters of graphene material in the desired frequency range are investigated and its absorption capability is illustrated by calculating the attenuation constant of the electromagnetic wave. It is observed that broadband absorption is a consequence of wideband retrieved surface impedance matching with the free-space intrinsic impedance due to the tapered geometry. Moreover, the azimuthal and longitudinal cavity resonances with different orders are exhibited for a better understanding of the underlying wideband absorption mechanism. Importantly, the device can tolerate the oblique incidence in a wide span around 65°, regardless of the polarization. The proposed structure can be realized by large-area fabrication techniques.
在本文中，通过在难熔金属衬底顶部的壳状石墨烯基中空纳米柱实现了全太阳光谱覆盖，吸收效率高于96%。材料的选择保证了器件的高热稳定性以及其对恶劣环境条件的耐受性。为了设计该结构，研究了所需频率范围内石墨烯材料的本构参数，并通过计算电磁波的衰减常数来说明其吸收能力。据观察，宽带吸收是由于锥形几何形状导致宽带恢复表面阻抗与自由空间本征阻抗匹配的结果。此外，还展示了不同阶次的方位角和纵向腔共振，以便更好地理解潜在的宽带吸收机制。重要的是，该器件在约65°的宽范围内能够容忍斜入射，而与偏振无关。所提出的结构可以通过大面积制造技术实现。
