The increasing demand for efficient yet nonpolluting energy conversion technologies require the photovoltaic (PV) systems to have fine-tuned optical responses and suppressed thermalization. PV cells that are based on Silicon are commonly patterned via lithography and etching techniques to implement micro/nanoscale surface components to reduce their reflectance on a wide spectrum while enhancing their absorption of energies around and higher than its bandgap. In this way, the power output increases while increases in cell temperature (e.g., thermalization) is also expected. In this work, a nanopatterned Si PV cell is designed and optimized evaluating different surface nanostructures to suppress the reflectance only in the vicinity of Si bandgap energy, so the power output can be improved and the thermalization can be suppressed simultaneously. Two- and three-dimensional, periodic structures are simulated by finite-difference time-domain method and optimized via parameter sweep optimization technique. A figure of merit (FOM) is developed to compare the in-band and out-of-band front side reflectance. The results revealed that rectangular gratings provided higher FOM, thus better selectivity compared to triangular ones. Similarly, square prism nanostructures demonstrate better selectivity compared to pyramid structures. Rigorous correlation analyses revealed that the selectivity is more strongly correlated with the height than the width. It is demonstrated that with optimized square prism nanostructures, 20 % increase of the absorption of useful radiation is accompanied by a thermalization that is limited to 15 %. With pattern optimization, it is shown that the electrical power output can be improved without producing substantial increase in the cooling load of solar cells.

中文翻译：

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抑制纳米图案化硅光伏电池的窄带反射


对高效且无污染的能源转换技术的需求不断增长，这要求光伏 （PV） 系统具有微调的光学响应和抑制热化。基于硅的 PV 电池通常通过光刻和蚀刻技术进行图案化，以实现微/纳米级表面组件，以降低它们在宽光谱上的反射率，同时增强它们对周围和高于带隙的能量的吸收。通过这种方式，功率输出增加，同时预计电池温度也会升高（例如，热化）。在这项工作中，设计并优化了一种纳米图案化的 Si PV 电池，评估不同的表面纳米结构，以仅在 Si 带隙能量附近抑制反射率，从而提高功率输出并同时抑制热化。采用有限差分时域法对二维和三维周期性结构进行仿真，并通过参数扫描优化技术进行优化。开发了一个品质因数 （FOM） 来比较带内和带外正面反射率。结果表明，矩形光栅提供了更高的 FOM，因此与三角形光栅相比具有更好的选择性。同样，与金字塔结构相比，方柱纳米结构表现出更好的选择性。严格的相关性分析表明，选择性与高度的相关性比与宽度的相关性更强。结果表明，使用优化的方棱镜纳米结构，有用辐射的吸收增加 20%，同时热化限制在 15%。通过图案优化，结果表明可以提高功率输出，而不会大幅增加太阳能电池的冷却负荷。