High-performance near-field thermophotovoltaics based on multilayer hyperbolic materials

The near-field thermophotovoltaics (NF-TPV), as a solid-state energy converter, enables thermal-to-electric energy conversion efficiently due to the coupling of evanescent waves, holding great potential in waste heat recovery. Studies suggest that hyperbolic phonon polaritons (HPhPs) excited in natural hyperbolic materials (HMs) have promising prospects to improve NF-TPV performance. However, the impact of coupling of HPhPs within multilayer HM structures on NF-TPV systems remains unexplored. Here, we study an NF-TPV system in which a periodic multilayer structure composed of different HMs serves as the thermal emitter, with InSb PV cell acting as the receiver. The numerical results show that the Two-cell structure achieves an output power of 1.22 x 104 W/ m2 at a temperature of 900 K, surpassing the output power of the CaCO3-InSb and hBN-InSb structures by 2.17 and 1.12 times, respectively. The improved performance owes credit to the strong coupling of HPhPs above the band gap of the PV cell. The study offers a new approach to enhance the performance of NF-TPV systems in waste heat recovery and the utilization of renewable energy.