Refractory material based frequency selective emitters/absorbers for high efficiency and thermal stable thermophotovoltaics

•A refractory material based broadband selective emitter is demonstrated.•The filling dielectrics shifts the cut-off wavelength conveniently.•A thermal stability is demonstrated at 1073 K thermal annealing.

Refractory materials based frequency selective emission/absorption is extremely encouraging for various applications, especially the combustion based thermophotovoltaics (TPV) and solar-TPV systems. The frequency selective emitters/absorbers also face the challenges of robust operation at elevated temperatures. Here, we report titanium nitride based thermal stable emitters/absorbers with good selectivity in the near infrared wavelength range. The titanium nitride nanocavitity array provides high emissivity/absorptivity at the desired short wavelength range but suppressed emissivity/absorptivity at the long wavelength range, and this design could be used to obtain high power density of the TPV system. The cut-off wavelength could be adjusted by encapsulating the cavities with different dielectrics. Meanwhile, the encapsulating layer protects the nanocavity structure from deformation at high temperatures. The thermal stability at 1073 K and 1273 K for two hours in Argon was demonstrated for the encapsulated nanocavity structure.