One-dimensional microstructure tungsten gratings for thermo photovoltaic applications

In this study, a one-dimensional microstructure tungsten grating is optimized for potential application as Thermo Photovoltaic (TPV) emitter. The influence of gratings geometric parameters on the spectral emittance are studied by using the Rigorous Coupled-Wave Analysis (RCWA). The results show that the spectral emittance is affected by the gratings geometrical parameters and insensitive to the direction. The optimum parameters of the proposed structure are grating period 1.4 μm, a filling ratio 0.8 and grating height 0.2 μm. A broad peak of high emittance is obtained at wavelengths between 0.5 and 1.8 μm. A peak emittance close to unity at wavelengths between 0.5 and 2 μm is achieved and it drops below 0.2 at wavelengths above 2 μm. This can be explained by the surface plasmon polaritons excitation coupled with the grating microstructures. At longer wavelengths, the emittance remains low and this is highly desired for thermo photovoltaic applications to reduce the thermal leakage due to low-energy photons that do not produce any photocurrent. The proposed structure can be used as a selective emitter for TPV applications.