Perrakis George, Tasolamprou Anna C, Kenanakis George, Economou Eleftherios N, Tzortzakis Stelios, Kafesaki Maria
Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), 70013, Heraklion, Crete, Greece.
Department of Materials Science and Technology, University of Crete, Heraklion, Crete, Greece.
Sci Rep. 2021 Jun 2;11(1):11552. doi: 10.1038/s41598-021-91061-1.
Outdoor devices comprising materials with mid-IR emissions at the atmospheric window (8-13 μm) achieve passive heat dissipation to outer space (~ - 270 °C), besides the atmosphere, being suitable for cooling applications. Recent studies have shown that the micro-scale photonic patterning of such materials further enhances their spectral emissivity. This approach is crucial, especially for daytime operation, where solar radiation often increases the device heat load. However, micro-scale patterning is often sub-optimal for other wavelengths besides 8-13 μm, limiting the devices' efficiency. Here, we show that the superposition of properly designed in-plane nano- and micro-scaled periodic patterns results in enhanced device performance in the case of solar cell applications. We apply this idea in scalable, few-micron-thick, and simple single-material (glass) radiative coolers on top of simple-planar Si substrates, where we show an ~ 25.4% solar absorption enhancement, combined with a ~ ≤ 5.8 °C temperature reduction. Utilizing a coupled opto-electro-thermal modeling we evaluate our nano-micro-scale cooler also in the case of selected, highly-efficient Si-based photovoltaic architectures, where we achieve an efficiency enhancement of ~ 3.1%, which is 2.3 times higher compared to common anti-reflection layers, while the operating temperature of the device also decreases. Besides the enhanced performance of our nano-micro-scale cooler, our approach of superimposing double- or multi-periodic gratings is generic and suitable in all cases where the performance of a device depends on its response on more than one frequency bands.
包含在大气窗口（8 - 13微米）具有中红外发射材料的户外设备，除了大气之外，还能实现向外太空（约 - 270°C）的被动散热，适用于冷却应用。最近的研究表明，此类材料的微尺度光子图案化进一步提高了它们的光谱发射率。这种方法至关重要，特别是对于白天运行而言，因为太阳辐射常常会增加设备的热负荷。然而，微尺度图案化对于8 - 13微米以外的其他波长往往并非最优，限制了设备的效率。在此，我们表明，对于太阳能电池应用而言，适当设计的平面内纳米和微米尺度周期性图案的叠加会导致设备性能增强。我们将这一理念应用于简单平面硅基板顶部的可扩展、几微米厚且单一材料（玻璃）的辐射冷却器，在那里我们展示了约25.4%的太阳能吸收增强，同时温度降低了约≤5.8°C。利用耦合的光电热模型，我们还在选定的高效硅基光伏架构的情况下评估了我们的纳米 - 微米尺度冷却器，在那里我们实现了约3.1%的效率提升，这比普通抗反射层高2.3倍，同时设备的工作温度也降低了。除了我们的纳米 - 微米尺度冷却器性能增强之外，我们叠加双周期或多周期光栅的方法具有通用性，适用于设备性能取决于其对多个频段响应的所有情况。
