Enhanced and tunable near-field thermophotovoltaics driven by hybrid polaritons

Near-field thermophotovoltaics (NF-TPV) offers the potential for achieving elevated power density and conversion efficiency by leveraging the amplification of thermal radiation within a nanoscale gap. Here, we propose an NF-TPV device with a sandwich emitter composed of calcite film and graphene layer. The results show that this sandwich configuration can significantly enhance output power, outperforming monolayer-graphene-covered heterostructures and the single calcite film. These are because the sandwich configuration can enhance hybrid polaritons, which are formed by the coupling between surface plasmon polaritons in graphene and hyperbolic phonon polaritons in calcite. In addition, the effects of graphene chemical potentials on the performance of NF-TPV devices are also studied. The tunable power density range of the sandwich structure can be up to 3.26 times that of other structures by altering the chemical potential of graphene. The findings presented here may unpack a promising path for enhancing and manipulating the performance of NF-TPV at the nano- and microscale.