Non-Hermitian selective thermal emitter for thermophotovoltaics

For a sustainable future, efficient, compact, and solid-state energy converters are critical. Thermophotovoltaics (TPV)—a solid-state scheme to convert heat into electricity—is promising for thermal storage and generation1. TPV systems employing selective thermal emitters allow compact designs for various terrestrial and space applications and, hence, have garnered much attention. Despite significant research efforts, these systems have low efficiency. The selective thermal emitter and the low-bandgap photovoltaic cell contribute to this problem. Here, we solve the shortcomings of the thermal emitter by using a novel approach inspired by non-Hermitian optics. We demonstrate a hybrid metal-dielectric non-Hermitian selective emitter (NHE) with high spectral efficiency (> 60%) and employ the NHE in a TPV system operating at 1273 K. We show that a maximum TPV conversion efficiency of 12% is possible at 1273 K, though our preliminary experiments employing an uncooled PV cell showed a much lower efficiency.