A high-performance, metallodielectric 2D photonic crystal for thermophotovoltaics

Fuel-combustion-based thermophotovoltaic (TPV) systems are emerging as a viable power source for small, portable generators spectrum of applications such UAVs, robotic platforms, and sensors. In TPV systems, an emitter heated to above 1000 K emits radiation that is then converted electricity by low bandgap photovoltaic cell. One promising class emitters two-dimensional photonic crystals (PhCs) made tantalum, which have shown high-temperature stability at 1150–1250K over hundreds hours [1], [2] been implemented in prototype system with 4.4% fuel-to-electricity efficiency [1]. Tantalum PhCs filled capped hafnium oxide can enable even higher optical performance in-band emissivities 0.8–0.9. However, two key features difficult realize simultaneously: uniformly cavity thin capping layer [3], [4]. Here, we present process results reduced roughness better thickness control the layer. We use room temperature reflectance measurements full simulations estimate gains. This selective paves way toward efficient, practical, mesoscale generators.