Enhancing thermophotovoltaic performance using metamaterial-bridge-based near-field heterostructures

Near-field thermophotovoltaic (NFTPV) has gradually emerged as a highly promising energy conversion technology owing to its super-Planckian thermal radiation energy transfer characteristics, but achieving higher performance output remains a pressing challenge to be addressed. To enhance energy transfer and output, we introduce a Ti-metamaterial bridge system composed of an InAs photovoltaic cell, a Ti-metamaterial bridge and a gold (Au) substrate acting as a reflector. Benefiting from the electromagnetic local characteristics above the bandgap provided by the Ti-metamaterial bridge, which supports the transmission of large wave vectors, the nanowire system achieves an output power density up to 4.66 times that of the bridge-free system and an energy conversion efficiency of approximately 19%. In addition, the Ti-metamaterial bridge system exhibits excellent robustness. When the bridge thickness varies from 100 nm to micrometer scale or when the bridge volume fraction changes, the performance enhancement remains remarkable. Particularly, the nanohole system exhibiting elliptical electromagnetic modes demonstrates unexpectedly stable performance with respect to thickness variations. This work provides a potential material-oriented strategy for designing high-power output and compact thermophotovoltaic converters.