Detailed balance evaluation of tandem thermophotovoltaic devices residing on 6.1 Å Sb-based alloys

•InAs0.91Sb0.09 can be an attractive low-temperature thermophotovoltaic material.•GaInAsSb/InAsSb dual-junction device is an efficient low-temperature converter.•Realistic triple-junction device can be constructed from the 6.1 Å Sb-based alloys.

Following the detailed balance principle, we have systematically investigated the electricity generation from the infrared thermal radiation by 6.1 Å Sb-based converters. By simulating the converters in their possible single/multiple-junction configurations, the GaSb lattice-matched InAs0.91Sb0.09 alloy has been demonstrated not only to be an attractive converter for a broadband emitter operating at 1200–1500 K but also a potential subcell candidate to design high-performance tandem converters. To construct the tandem converters, it is shown that, for both mechanically-stacked and series-interconnected configurations, the GaInAsSb alloy's optimum bandgap Ego dependence on the emitter temperature TBB easily yields a quadratic equation Ego=αTBB2+βTBB+γ with αα, ββ, and γγ the fitted structure-dependent parameters. These results provide some favorable guidelines to develop more powerful thermophotovoltaic devices.