Minimizing phonon conduction across nanostructures is necessary for blocking parasitic heat conduction that limits thermoelectric energy conversion efficiency at the nanoscale. Width-modulated nanowaveguides have been proposed as thermoelectric metamaterials with enhanced thermoelectric efficiency compared to the corresponding uniform nanowaveguides. In this class of metamaterials, thermal transmission decreases in a controlled manner with an increasing degree of modulation. Aperiodicity can be designed to minimize coherent phonon conduction by maximizing disorder in the modulation profile according to a physics rule. Here, we propose a two-step methodology to design width modulation for minimum phonon conduction. This involves optimizing first the width-mismatch and then the aperiodic width-modulation profile. We demonstrate efficient optimization using calculations and Bayesian optimization. Our work provides new design guidance towards optimizing thermoelectric metamaterials for maximum thermoelectric efficiency.

最小化跨纳米结构的声子传导对于阻止寄生热传导是必要的，寄生热传导限制了纳米尺度的热电能量转换效率。宽度调制纳米波导已被提议作为热电超材料，与相应的均匀纳米波导相比，其热电效率更高。在此类超材料中，随着调制程度的增加，热传输以受控方式降低。非周期性可以被设计为通过根据物理规则最大化调制分布中的无序来最小化相干声子传导。在这里，我们提出了一种两步方法来设计宽度调制以实现最小声子传导。这涉及首先优化宽度失配，然后优化非周期性宽度调制轮廓。我们使用计算和贝叶斯优化来演示有效的优化。我们的工作为优化热电超材料以实现最大热电效率提供了新的设计指导。