Semiconductor Manufacturing International Corporation , 18 Zhangjiang Road , Shanghai 201203 , China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics , Chinese Academy of Sciences , Shanghai 200050 , China.
ACS Appl Mater Interfaces. 2018 Jun 27;10(25):21372-21380. doi: 10.1021/acsami.8b06533. Epub 2018 Jun 18.
Currently, the application of thermoelectric power generators based on BiTe-based alloys for the recovery of low-quality waste heat is still limited because of the aggravated intrinsic excitation of the material at elevated temperatures. In this study, excessive Te and dopant I are introduced to the n-type BiTeSe material with the purpose of suppressing its intrinsic excitation and improving the thermoelectric performance at elevated temperatures. These Te and I atoms act as electron donors to effectively reduce the density of minority carriers (holes) and weaken their negative contribution to the Seebeck coefficient. Likewise, the initial band structure and the carrier scattering mechanism are scarcely altered. Similar to the p-type BiTe-based alloys, we found the "conductivity-limiting" mechanism is also well obeyed in the present n-type BiTeSe-based materials. The reduced minority carrier partial electrical conductivity in these Te-excessive and I-doped BiTeSe samples significantly decreases the bipolar thermal conductivity, leading to lowered total thermal conductivity at elevated temperatures. Finally, the peak zT is successfully shifted up to higher temperatures for these Te-excessive and I-doped BiTeSe samples. A maximum zT of 1.0 at 400 K and an average zT of 0.8 at 300-600 K have been realized in Te-excessive BiTeSe.
目前，基于 BiTe 基合金的热电发电机在回收低品质余热方面的应用仍然受到限制，这是因为材料在高温下的本征激发加剧了。在这项研究中，向 n 型 BiTeSe 材料中引入过量的 Te 和掺杂剂 I，以抑制其本征激发并提高高温下的热电性能。这些 Te 和 I 原子作为电子供体，有效地降低了少数载流子（空穴）的密度，并削弱了它们对 Seebeck 系数的负面影响。同样，初始能带结构和载流子散射机制几乎没有改变。与 p 型 BiTe 基合金类似，我们发现本征激发抑制机制在 present n 型 BiTeSe 基材料中也得到了很好的遵循。这些 Te 过量和 I 掺杂的 BiTeSe 样品中少数载流子部分电导率的降低显著降低了双极热导率，从而降低了高温下的总热导率。最终，这些 Te 过量和 I 掺杂的 BiTeSe 样品的峰值 zT 成功地转移到更高的温度。在 Te 过量的 BiTeSe 中实现了在 400 K 时 zT 值为 1.0 的最大值和在 300-600 K 时平均 zT 值为 0.8。
