Power dense thermophotovoltaic cells

Class-leading 2-junction (2J) thermophotovoltaic (TPV) cells have been developed with thermophotovoltaic efficiency exceeding 40%. However, these devices have sub-optimal power density because the subcell bandgaps are not matched to the emitter spectrum. Although efficiency is important, power density is also an important metric to gauge TPV cell performance; the greater the power density, the less total area of TPV cells that are needed to satisfy a given power generation target. To quantify the relevance of power density, spectrum-matched 1.04/0.78/0.62/0.48/0.36 eV 5-junction (5J) TPV cells have the potential to be 3.5 times more power dense than state-of-the-art, yet spectrum-mismatched, 1.4/1.2 eV 2J TPV cells when irradiated by a 2400 °C emitter. The proposed 5J TPV cells also have the potential to exceed 40% standard power conversion efficiency.