Surface microstructured selective emitters for TPV systems

Surface microstructured selective emitters for thermophotovoltaic generators are fabricated with lithography and Si anisotropic etching techniques. Two-dimensional series of reverse-pyramid cavities are fabricated on the surface with the structural periods of 1.5 and 2.0 μm. Thermal radiation spectra of the emitters are measured at high temperatures and selective emission due to the surface microstructures is clearly observed. Numerical calculations based on rigorous coupled-wave analysis (RCWA) are also performed to predict spectral properties of the emitters. Experimentally observed emission peaks are well reproduced by the calculation. It is also expected from the calculation that the selective emission due to these microstructures will show little directionality. An evaluation of selective emission efficiency shows that microstructured selective emitters are effective to improve efficiencies of TPV generation systems