One-dimensional Si/SiO ₂ photonic crystal filters for Ga _x In _1−x As _y Sb _1−y thermophotovoltaic devices

With crystalline silicon and silicon oxide, we demonstrate the as-formed one-dimensional photonic crystal filter, in both the general and modified configurations, to reshape the thermal spectrum for Ga x In 1−x As y Sb 1−y devices. Including the inherent dispersive dielectric properties of sublayers, our calculations indicate that the optimal filters only have five silicon–silicon oxide units, and the central wavelength of the filter deviates from that for nondispersive properties on the order of 0.04−0.06 λ C (the cutting-off wavelength of the underlying cell). For a 0.5 eV GaInAsSb cell, the application of the optimized central wavelength gives rise to a net improvement of spectrum efficiency on the order of ∼2%, which can be further amplified to 6%–7% by adding a nonzero aperiodic factor for the front and rear units. Our observations offer some favorable strategies to efficiently manage the thermal-to-electricity energy conversion in Ga x In 1−x As y Sb 1−y thermophotovoltaic systems.