Nanolayered Wavelength-Selective Narrowband Thermal Emitters for Solar Thermophotovoltaics

To enhance the efficiency of a solar thermophotovoltaic system, one of the challenges is to develop a thermal emitter with narrowband emission at a selected wavelength to efficiently match the bandgap of a bottom photovoltaic cell. Here, we propose a nanolayered narrowband thermal emitter with a-SiNx and a-SiNyOz alternatively stacked nanolayers deposited on a polished silicon substrate covered by metallic molybdenum. The fabricated Si-Mo-SiNx/SiNyOz emitters exhibit a good narrowband absorption with an absorptance of above 90% at the designed emission wavelength based on a Tamm plasmon polariton, while the absorption spectra can be tuned by simply changing the thickness of the multilayers. Due to the large imaginary part of the dielectric function of Mo as well as the better stability compared with tungsten (W), a suppressed absorption as low as 1.4% can be achieved within the wavelength region of 2–7 μm and the fabricated emitters exhibit a high resistance to high-temperature treatment in an air atmosphere. The simulated solar thermophotovoltaic system efficiency reaches 28.9% under a solar concentration of 1000 based on the proposed emitter. Such a nanolayered wavelength-selective thermal emitter can be potentially applied in high-performance thermophotovoltaic systems.