Abstract
Structured spectrally selective emitters show good spectral performance in thermophotovoltaic (TPV) systems, but most of them cannot maintain good spectral emittance at high temperatures as expected. A Mo-doped HfO2 monolayer structure was proposed to improve the thermal stability of the structured emitters. A simulation model based on the transfer matrix method and effective medium theory was used to design the doped monolayer emitters. Thermal annealing and characterization measurements were conducted to investigate the proposed emitter after 1273 K–1473 K thermal annealing, and a TPV system model was built to evaluate their spectral performance after thermal annealing. The results revealed that 20% Mo doping can improve the spectral performance of a 90 nm HfO2 monolayer structure, making the spectral efficiency up to 60.93% at 1273 K. Due to the combined action of the Mo oxidation, grain growth and phase transition of HfO2 during thermal annealing, the formation of holes and Mo oxides were observed. Consequently, the spectral emittance of the doped emitters changed. Nevertheless, no obvious decline in the system efficiency (approximately 1%) of the TPV system with the doped emitter after 1273K thermal annealing for 12 h was observed. The proposed Mo-doped HfO2 monolayer emitter shows good spectral performance compared with the undoped one. The investigation of the thermal degradation of the proposed emitters can lay a foundation for promoting their applications of TPV systems.
Published Version
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