ABSTRACT The output power of thermophotovoltaic (TPV) cells may be greatly increased when the gap between the emitter and cell is reduced to submicron distances (near-field regime), at which photon tunneling due to evanescent waves becomes important. Accurate modeling of TPV cells in these conditions is crucial for the design and optimization of near-field TPV systems. The conventional or standard modeling method uses the summation of the dark current and the short-circuit current, while the direct method applies the photon chemical potential. It has been shown that the two methods are linked through a modification of the direct method using Wien’s approximation. By contrasting different modeling approaches, we quantitatively analyze the effects of evanescent waves on the TPV cell performance parameters, especially the dark current, for different emitter and cell materials in the near-field regime. Our results show that the saturation current by radiative recombination is strongly affected by evanescent waves and the bandgap energy. The current-voltage characteristics calculated by different modeling methods are displayed to demonstrate that a constant saturation current typically used in the standard method could cause substantial error in the near-field regime. For a TPV system with an emitter operating at relatively low temperatures, we show that it is necessary to include the photon chemical potential in the computation of the net radiative heat transfer between the emitter and receiver.

中文翻译：

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渐逝波对热光伏电池暗电流的影响

摘要 当发射器和电池之间的间隙减小到亚微米距离（近场区域）时，热光伏 (TPV) 电池的输出功率可能会大大增加，此时由倏逝波引起的光子隧穿变得很重要。在这些条件下对 TPV 电池进行准确建模对于近场 TPV 系统的设计和优化至关重要。常规或标准建模方法使用暗电流和短路电流的总和，而直接方法应用光子化学势。已经表明，这两种方法是通过使用 Wien 近似对直接方法进行的修改而联系起来的。通过对比不同的建模方法，我们定量分析了倏逝波对 TPV 电池性能参数的影响，尤其是暗电流，用于近场区域中不同的发射极和电池材料。我们的结果表明，辐射复合引起的饱和电流受到渐逝波和带隙能量的强烈影响。显示了通过不同建模方法计算的电流 - 电压特性，以证明标准方法中通常使用的恒定饱和电流可能会导致近场区域中的大量误差。对于发射器在相对较低温度下运行的 TPV 系统，我们表明在计算发射器和接收器之间的净辐射热传递时必须包括光子化学势。显示了通过不同建模方法计算的电流 - 电压特性，以证明标准方法中通常使用的恒定饱和电流可能会导致近场区域中的大量误差。对于发射器在相对较低温度下运行的 TPV 系统，我们表明在计算发射器和接收器之间的净辐射热传递时必须包括光子化学势。显示了通过不同建模方法计算的电流 - 电压特性，以证明标准方法中通常使用的恒定饱和电流可能会导致近场范围内的重大误差。对于发射器在相对较低温度下运行的 TPV 系统，我们表明在计算发射器和接收器之间的净辐射热传递时必须包括光子化学势。