Random Rough Surface Effects on the Performance of Near-Field Thermophotovoltaic System

Abstract

Surfaces roughness exists inevitably during manufacturing process, while how it affects the performance of the near-field thermophotovoltaic (NF-TPV) system is still unclear. In this work, we investigate the effect of rough surfaces on the performance of NF-TPV systems theoretically. Two typical NF-TPV systems with the same plasmonic emitter (Ga-doped ZnO, GZO) and different TPV cells (GaSb and InAs) are considered. The effective multilayer approach and analytical approximation model is applied to analyze the near-field heat transfer and the performance of NF-TPV system. Near-field heat transfer between the ideal GZO and TPV cell with smooth surfaces is through the TR-SPPs modes (interaction between the evanescent waves generated by total reflection and the surface plasmon polaritons), while the surface roughness excites the red-shift and the coupling of the TR-SPPs modes.The near field heat flux is enhanced below the resonance frequency of the plasmonic emitter due to the red-shifted coupled modes. The influence of surface roughness on the performance of the NF-TPV system depends on the cooperation between the resonance frequency of the emitter and the bandgap of TPV cell. Generally, the power outputs are improved, while the efficiency can be improved or reduced with the increase of surface roughness, for the considered NF-TPV systems. This work will help the understanding and evaluation of the performance of NF-TPV system with rough surfaces.

Keywords: Thermophotovoltaic, Near-field heat transfer, Rough surface, Surface roughness