Conversion of heat to electricity via solid-state devices is of great interest and has led to intense research of thermoelectric materials^1,2. 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^{3,4,5,6,7,8,9,10,11,12} suggest that near-field (NF) effects^{13,14,15,16,17,18} 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.

通过固态设备将热量转换为电能引起了人们的极大兴趣，并导致对热电材料^1,2的深入研究。固态热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间隙并被光伏（PV）电池吸收以产生电能。原则上，这样的系统还可以实现更高的效率并在使用中提供更多的多功能性。然而，热发射器的典型温度仍然太低（<1,000 K），无法实现足够的光通量到PV电池，从而限制了实际应用。理论建议^{3,4,5,6,7,8,9,10,11,12}表明近场效应（NF）^{13,14,15,16,17,18}可以利用纳米间隙中产生的能量来增加流向PV电池的光子通量，并显着提高功率输出。在这里，我们描述了由微型加工系统和定制纳米定位器组成的功能性NFTPV设备，并证明了相对于远场，在标称60 nm的间隙处，功率输出提高了约40倍。我们在间隙尺寸和发射极温度范围内，以及具有两种不同带隙能量的PV电池中，系统地表征了这种增强。我们预计，一旦优化，这项技术将可用于余热回收应用。