A novel, to the best of our knowledge, design of a wavelength-selective solar thermophotovoltaic (STPV) absorber based on a 2D square spiral grating is numerically proposed and analyzed. The suggested STPV absorber is made of tungsten (W) with a spacer of aluminum-doped zinc oxide (AZO). In particular, the AZO is epsilon-near-zero material where its dielectric permittivity can be engineered over a broad wavelength range in the near-infrared. The refractory AZO-W metamaterial exhibits marked radiative optical properties, which control the thermal absorption through an engineered dielectric response function. The geometrical parameters and optical properties of the proposed design are studied using the finite difference time domain method to maximize the absorption through the studied wavelength range. The physical mechanism beyond the geometrical effects is also investigated with the inductor and capacitor model. The 2D square spiral STPV absorber achieves the photon-to-heat conversion efficiency of 75.2% at 1000 K. It is also found that the absorption of the proposed STPV absorber is insensitive to the incident angles from normal incident to 60º for transverse magnetic and transverse electric polarizations. The absorption enhancement is due to the effective coupling among the magnetic polariton, surface plasmon polariton, and intrinsic losses of the tungsten metal.

中文翻译：

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基于二维方形螺旋设计的ε-近零超材料吸热器

据我们所知，一种新颖的基于二维方形螺旋光栅的波长选择性太阳能热光伏 (STPV) 吸收器的设计被数值化地提出和分析。建议的 STPV 吸收器由钨 (W) 和铝掺杂的氧化锌 (AZO) 隔板制成。特别是，AZO 是 epsilon 接近零的材料，它的介电常数可以在近红外的宽波长范围内进行设计。难熔的 AZO-W 超材料具有显着的辐射光学特性，可通过工程介电响应函数控制热吸收。使用有限差分时域方法研究了所提出设计的几何参数和光学特性，以在研究的波长范围内最大化吸收。还使用电感器和电容器模型研究了几何效应之外的物理机制。二维方形螺旋 STPV 吸收器在 1000 K 下实现了 75.2% 的光子热转换效率。还发现所提出的 STPV 吸收器的吸收对从垂直入射到 60º 的横向磁场和横向入射角不敏感。电极化。吸收增强是由于磁极化子、表面等离子体极化子和钨金属的固有损耗之间的有效耦合。还发现，对于横向磁极化和横向电极化，所提出的 STPV 吸收器的吸收对从法向入射到 60º 的入射角不敏感。吸收增强是由于磁极化子、表面等离子体极化子和钨金属的固有损耗之间的有效耦合。还发现，对于横向磁极化和横向电极化，所提出的 STPV 吸收器的吸收对从法向入射到 60º 的入射角不敏感。吸收增强是由于磁极化子、表面等离子体极化子和钨金属的固有损耗之间的有效耦合。