Near-Field Thermophotovoltaic Conversion with High Electrical Power Density and Cell Efficiency above 14%

Abstract

A huge amount of thermal energy is available close to material surfaces in radiative and nonradiative states, which can be useful for matter characterization or energy harvesting. Even though a full class of novel nano-engineered devices has been predicted over the last two decades for exploiting near-field thermal photons, efficient near-field thermophotovoltaic conversion could not be achieved experimentally until now. Here, we realize a proof of principle by approaching a micron-sized indium antimonide photovoltaic cell at nanometer distances from a hot (~800 K)

Integrated Near-Field Thermophotovoltaic Device Overcoming Blackbody Limit

“…Using this device, we demonstrate a large photocurrent of 14.9 mA (density: 1.49 A/cm 2 ) at an emitter temperature of 1192 K, which is 1.5 times larger than the blackbody limit at the same temperature. In addition, we obtain an output power of 1.92 mW (density: 0.192 W/cm 2 ) and a system conversion efficiency of 0.7%, both of which are greater than those of the previously reported near-field TPV systems − by 1 to 2 orders of magnitude. Furthermore, we theoretically predict that a system efficiency of >35% can be achieved in the up-scaled device with photon recycling, demonstrating the potential of our integrated near-field TPV device in practical applications.…”

“…Thermal radiation transfer between two objects that are separated by a subwavelength gap can be orders of magnitude larger than the maximal radiation transfer in free space (the blackbody limit) owing to the contribution of evanescent waves. − This concept has attracted significant attention in both fundamental science and various energy-related applications in recent years. The thermophotovoltaic (TPV) systems, − which convert heat into electricity by irradiating PV cells with thermal radiation from heated emitters, can significantly benefit from near-field thermal radiation transfer owing to the potential to increase output power density and conversion efficiency. − Since the first experimental investigation of near-field TPV systems in 2001, several quantitative demonstrations of near-field TPV systems have been reported in recent years. − For example, in ref , an 80-μm-diameter Si thermal emitter and a 300-μm × 300-μm mid-infrared photodetector were brought closer to a 60 nm distance using a piezo-controlled experimental setup, and 40-fold enhancement in the output power density was achieved. Another recent work demonstrated a near-field TPV system composed of a 40-μm-diameter graphite emitter and a 20-μm-diameter InSb PV cell cooled at 77 K, where an output power density of 0.75W/cm 2 and a near-field cell conversion efficiency of 14% were obtained (the detailed configurations and performances of the previous systems − are provided in Supporting Information (SI) Section 7).…”

Comprehensive analysis of optimized near-field tandem thermophotovoltaic system

“…The vacuum gap between them is fixed to 100 nm except for the cases discussed in the last two paragraphs in Section 3. Please note that the 100-nm-gap between the emitter and the TPV cell is an achievable gap considering the experimentally validated state-of-the-art NFTPV systems [37][38][39][40].…”

Tunable Color-Variable Solar Absorber Based on Phase Change Material Sb2Se3

“…Solar cells with higher conversion efficiency can reach 47.1% by the combined action of multiple semiconductor materials with different band gaps [ 9 ], but they require near-perfect materials and multiple absorption band gaps. Solar photothermal conversion can be applied to thermophotovoltaic [ 10 , 11 , 12 , 13 ] and thermoelectric power generation [ 14 , 15 , 16 ], and catalytic hydrolysis [ 17 , 18 , 19 , 20 ]. At the same time, the utilization of light energy is higher, the material requirements are lower, and the equipment structure is simpler and has a low failure rate.…”