Toward high-efficiency selective emitters at elevated temperatures with particle doping via synergistic regulation of intrinsic and structural effects

Abstract

Particle-doped emitters have been investigated in thermophotovoltaic (TPV) systems, where emissivity is controlled by particle composition and volume fraction. However, the impacts of intrinsic optical properties (n, κ) and particle structural parameters on the emission spectrum are often treated separately, and their coupled synergy in emissivity control remains insufficiently elucidated. Here, an α-Fe 2 O 3 particle-doped HfO 2 coating on a ZrO 2 substrate was proposed as a selective emitter. A theoretical model based on Lorenz–Mie theory and Monte Carlo ray tracing was established to analyze emissivity, resolve scattering–absorption synergy, and evaluate system efficiency for GaSb-TPV. The predicted emissivity agrees with measurements after annealing in air at 1500 K for 6 h, indicating selective emission with high temperature stability. The emissivity spectrum can be decomposed into intrinsic absorption and scattering-assisted components to interpret spectral selectivity. Under strong absorption, emissivity was redistributed by scattering, whereas under weak absorption, emissivity was enhanced through scattering–absorption synergy. This synergy is governed by optical thickness and scattering statistics via coating thickness L , particle volume fraction f v , and particle radius r , regulating above-bandgap emissivity and sub-bandgap radiative loss. For GaSb-TPV conditions, the model-predicted optimum was obtained at L = 7 μm, f v = 0.05, and r = 0.129 μm, yielding η sys = 9.46%, surpassing the 8.4% efficiency of air-stable Er 2 O 3 emitters, while maintaining thermal stability at 1500 K relative to thermally vulnerable micro-metallic emitters. The spectral decomposition clarifies scattering–absorption synergy and provides a theoretical basis for optimizing particle-doped selective emitters toward high-temperature, high-efficiency TPV systems.