Microgap thermophotovoltaic systems with low emission temperature and high electric output

We theoretically show that a thermophotovoltaic (TPV) system enhanced by a wire metamaterial opens the door to a prospective microgap TPVs which will combine high electric output with relatively low temperatures of the emitter. The suggested system comprises an array of parallel metal nanowires grown on top of a photovoltaic semiconductor and standing free in the vacuum gap between the host dielectric layer and the emitter, so that their ends are sufficiently close to the emitting surface. Due to the resonant near-field coupling between this wire medium and the emitter and due to the optimized layered structure of the whole system, the strongly super-Planckian radiative heat flux of resonant nature is engineered. In the suggested system, heavily doped silicon and indium antimonide are considered as the materials for the emitter and the photovoltaic cell, respectively. Also, the parallel nanowires are made of tungsten. Employing the minority-carrier transport model, it is shown that a power output equal to 26 kW m^-2 can be achieved when the temperature of the doped-silicon emitter is only 500 °C.