高光谱吸收微纳结构表面提高太阳能温差发电性能的研究

采用飞秒激光等离子体丝（飞秒光丝）在金属铝箔表面以不同飞秒光丝扫描速度（5，15，25，35和45 mm·s-1）制备了微纳结构表面，并在太阳光能量主要覆盖的光谱范围（330～890 nm）内对其进行了反射率测量，发现飞秒光丝制备的微纳结构表面具有显著的高光谱吸收特性，并且飞秒光丝扫描速度越慢，光谱吸收率越强，5 mm·s-1条件下微纳结构表面光谱吸收率达97%以上。将制备的高光谱吸收微纳结构表面作为温差发电片（TEG）光吸收体，以此为基础构建了考虑太阳光辐照及温差发电模块（即TEG模块：结合微纳结构表面的TEG）散热情况的仿真实验环境并进行发电功率测量。研究结果表明，具有微纳结构的铝表面（5 mm·s-1制备条件下）与抛光铝箔或裸发电片相比，光电转化效率（发电效率）可分别提高43.3和10.7倍。进一步研究了TEG模块的温差发电的过程与机理，将TEG模块的温差发电过程分为光热（光能转化为热能）与热电（热能转化为电能）两个转化过程分析：首先在光热转化过程中，微纳结构表面增强了太阳光吸收效率，为光热转化提供更多的光子能量，实现了其在表面更多的热量沉积，进而在之后的热电转化过程中，更多的热能沉积使得TEG模块的载流子迁移率得到了很大提升，这样在同样的温差（发电片冷热端的温度差值）条件下，微纳结构表面与普通表面相比可以获得更高的热电转化效率。因此，微纳结构表面的高光谱吸收性能使得TEG模块经光热转化后得到的高热能沉积使载流子迁移率得到了提高，进而显著提升了TEG模块发电性能，这是微纳结构表面增强TEG温差发电效率的主要原因。这一机理的揭示，为TEG模块发电性能的进一步优化和提升提供了理论依据，对TEG模块的实际应用具有重要的意义。

Enhenced Performance of Solar-Driven Thermoelectric Generator with High Spectral Absorption Micro-Nano Structure Surfaces

Metal aluminum foil surface with micro-nano composite structure using femtosecond laser plasma filament (femtosecond filament) under different femtosecond filament scanning speed (5，15，25，35，45 mm·s-1)was prepared. In addition, the reflectivity measurements were carried out in the spectrum of sunlight energy mainly covered within the range (330~890 nm), and the result indicated that surface with micro-nano structure induced by femtosecond filament has significant high spectral absorption characteristic The slower the femtosecond filament scanning speed, the stronger the absorptivity/ Micro-nano structure surface absorption is even more than 97% under the condition of 5 mm·s-1. The prepared micro-nano structure surfaces with high spectral absorption are used as light absorbers of thermoelectric generator(TEG), on this basis, the simulation environment was established considering sunlight irradiation and heat dissipation of thermoelectric generator module (TEG module: combination of micro-nano structure metal surface with the TEG), and conducting power generation measurement. The results show that the photoelectric conversion efficiency (power generation efficiency) of aluminum surface with micro-nano structure (5 mm·s-1 preparation condition) can be increased by 43.3 times and 10.7 times respectively compared with polished aluminum foil or bare TEG. The generation process and mechanism of TEG module are further studied, the thermoelectric power generation process of TEG module is divided into two transformation processes to analyze: photothermal transformation process (optical energy converted into heat energy) and thermoelectric transformation process (heat energy converted into electricity): First in the photothermal conversion process, the presence of the micro-nano structure surface enhances the efficiency of sunlight absorption, to provide more photonic energy for photothermal conversion, implements the more heat deposition at the surface, and then in the subsequent thermoelectric transformation process, the carrier mobility of TEG module has been greatly improved by more heat deposition. Thus the micro-nano structure surface compared with the general surface can gain higher thermoelectric conversion efficiency under the condition of the same temperature difference (Temperature difference between hot and cold junctions of TEG module). Therefore, micro-nano structure on the surface of high spectral absorption performance makes TEG module to obtain high heat deposition after the photothermal conversion, bringing about promotion of the carrier mobility, and then increasing the TEG module power performance significantly, which is the main reason to significantly improve the power generation performance of TEG module. The discovery of this mechanism provides theoretical basis for further optimization and improvement of TEG module’s power generation performance, which is of great significance to the practical application of TEG module with micro-nano structural surface.