Nonreciprocal Solar Thermophotovoltaics

Compared to traditional solar cells, solar thermophotovoltaic (STPV) systems have the advantage of utilizing the full spectrum of solar radiation, but their thermodynamic efficiency is still far lower than the ultimate limit. This study shows that the efficiency deficit is caused by back emission from the intermediate layer toward the sun, resulting from the reciprocity of the system. The authors therefore propose using an intermediate layer with nonreciprocal radiative properties, which would suppress back emission and funnel more photons toward the cell, for a significant efficiency boost.