Fiorino Anthony, Zhu Linxiao, Thompson Dakotah, Mittapally Rohith, Reddy Pramod, Meyhofer Edgar
Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA.
Nat Nanotechnol. 2018 Sep;13(9):806-811. doi: 10.1038/s41565-018-0172-5. Epub 2018 Jun 18.
Conversion of heat to electricity via solid-state devices is of great interest and has led to intense research of thermoelectric materials. Alternative approaches for solid-state heat-to-electricity conversion include thermophotovoltaic (TPV) systems where photons from a hot emitter traverse a vacuum gap and are absorbed by a photovoltaic (PV) cell to generate electrical power. In principle, such systems may also achieve higher efficiencies and offer more versatility in use. However, the typical temperature of the hot emitter remains too low (<1,000 K) to achieve a sufficient photon flux to the PV cell, limiting practical applications. Theoretical proposals suggest that near-field (NF) effects that arise in nanoscale gaps may be leveraged to increase the photon flux to the PV cell and significantly enhance the power output. Here, we describe functional NFTPV devices consisting of a microfabricated system and a custom-built nanopositioner and demonstrate an ~40-fold enhancement in the power output at nominally 60 nm gaps relative to the far field. We systematically characterize this enhancement over a range of gap sizes and emitter temperatures, and for PV cells with two different bandgap energies. We anticipate that this technology, once optimized, will be viable for waste heat recovery applications.
通过固态器件将热转化为电引起了人们极大的兴趣，并引发了对热电材料的深入研究。固态热到电转换的替代方法包括热光伏（TPV）系统，其中来自热发射器的光子穿过真空气隙并被光伏（PV）电池吸收以产生电能。原则上，此类系统也可以实现更高的效率并在使用中提供更多的通用性。然而，热发射器的典型温度仍然过低（<1000 K），无法向光伏电池提供足够的光子通量，从而限制了实际应用。理论建议表明，可以利用纳米级间隙中出现的近场（NF）效应来增加光伏电池的光子通量，并显著提高功率输出。在这里，我们描述了由微制造系统和定制纳米定位器组成的功能性NFTPV器件，并证明在名义间隙为60 nm时，相对于远场，功率输出提高了约40倍。我们系统地表征了在一系列间隙尺寸和发射器温度下以及对于具有两种不同带隙能量的光伏电池的这种增强。我们预计，这项技术一旦优化，将可用于废热回收应用。
