Performance analysis of near-field tandem thermophotovoltaic systems based on radiative absorption distribution

Abstract

Fluctuational electrodynamics and minority carrier diffusion equations are applied to evaluate the electric power output of a near-field tandem thermophotovoltaic (TPV) system with a bulk tungsten emitter (at 1500 K) and InGaSb/InAs tandem cells (at 300 K). We give evidence of the superiority of the tandem TPV system over the single-junction TPV system in the near-field regime because a tandem structure can harvest useful photons in a wider spectral range. It is also found that in comparison with the system with a bulk tungsten emitter, the practically achievable indium‑tin‑oxide (ITO) emitter and multilayer emitter could enhance the electricity output by a factor of 1.7 and 2.9 as a result of the supported surface plasmon resonances and hyperbolic modes, respectively. The conversion efficiency of the ITO emitter is 6% higher due to the suppression of the surface recombination loss, but the efficiency of the multilayer emitter is even 15% lower because of the heavy bulk recombination loss. These results highlight the possibilities to enhance the performance of the near-field tandem TPV systems via optimizing the radiative absorption distribution in the tandem cells, which is paramount important for the design and improvement of near-field tandem TPV systems.