Nanostructured Radiation Emitters: Design Rules for High-Performance Thermophotovoltaic Systems

Wavelength-selective, nanostructured metallic radiation emitters are investigated for high-performance thermophotovoltaic (TPV) systems. After building evaluation tools to find the highly efficient selective emitters, studies of achieve emitter design schemes are systematically conducted by employing characterization factors of spectral cutoff efficiency and effective emittance efficiency. With identified ideal emissivity spectra and optimum geometric parameters of the selective emitters through the proposed design scheme, simply fabricated, three-dimensional photonic emitters comprising nickel inverse opal (Ni IO) structures are experimentally demonstrated. The Ni IO emitters exhibit the enhanced performance in terms of both spectral cutoff efficiency effective emittance and efficiency, as their plasmonic resonance at designated wavelengths augments the absorption property and hence the radiation property. An issue of the thermal deterioration of Ni IO emitters at high temperatures is resolved by applying a passivation layer consisting of thermally stable ceramic material. Details of optimal design rule, fabrication procedure, and quantitative characterizations in conjunction with various case studies offer directions toward high-performance radiation emitters in the context of energy harvesting TPV systems.