Sustaining efficiency at elevated power densities in InGaAs airbridge thermophotovoltaic cells

Recent work has demonstrated record-high thermophotovoltaic efficiency using thin-film InGaAs cells, but the power density of devices remains low. Elevated power densities are relevant to many thermophotovoltaic (TPV) applications, ranging from mobile generators to stationary energy storage of renewable electricity, and require effective management of heat and charge carriers. Here we investigate the use of single-junction InGaAs airbridge cells (ABCs) under such conditions. Experimental characterization of an InGaAs ABC with varying emitter and cell temperature is used to develop a predictive device model where carrier lifetimes and series resistances are the sole fitting parameters. The utility of this model is demonstrated through its use in identifying near-term opportunities for improving performance at elevated power densities, and for designing a thermal management strategy that maximizes overall power output. After accounting for the power necessary to cool the cells, this model shows that an InGaAs ABC with high material quality can reach a peak efficiency of ∼41% at 0.5 W/cm2, corresponding to an emitter temperature of 1070 °C, and sustain efficiencies above 36% up to 1.5 W/cm2.