Improved broadband spectral selectivity of absorbers/emitters for solar thermophotovoltaics based on 2D photonic crystal heterostructures.

We propose a novel heterostructure based on 2D photonic crystals as broadband selective absorbers/emitters for solar thermophotovoltaics. Alternating hafnium oxide (HfO2) and titanium oxide (TiO2) filled cylinder cavities with tetragonal lattices are embedded into antireflection-coated tungsten (W) film. The simulated results show that the designed structures can obtain high solar collection efficiency ηc of 87.9% as an absorber and great spectral emission efficiency ηe of 81.6% as an emitter. Meanwhile, high average absorptivity of 84.5% under 45° oblique incidence exhibits good performance of wide-angle absorption. This study provides a new way to acquire broadband spectral selective absorbers/emitters.