Study on thermal emission regulation based on refractory metal Mo microstructures

Thermal emitter, as one of the important components in the thermal photovoltaic system, is mainly used to absorb the energy radiated by the heat source and convert it into energy that can be absorbed by the photovoltaic cell. We use the RCWA algorithm to optimize the thermal emitter based on the refractory metal Mo microhole array with a quadrangular arrangement. The optimized structure has a high selective emissivity characteristic in the 1-2.4 μm waveband. The averaged emissivity can reach more than 79.6%, which is about 60% higher than that of the unstructured emitter; at the same time, the band emissivity gradually decreases after the wavelength of 2.4 μm, achieving a selective emission control. Using the laser direct writing technology, dry metal etching, and other micro-fabrication techniques, the thermal emitter is fabricated with the feature sizes as follows: the hole diameter, the array period, and the hole depth are 1 μm, 1.4 μm, and 3.4 μm, respectively; the area with microhole structures is 12×12 mm. The experimental measurement suggests that the averaged emissivity arrives at 70.07%. This study provides an alternative candidate for selective thermal emitters and also offers a technical experience for practical applications.