Thermoelectric enhancement for n-type PbS via synergistic effect of Ti doping and Cu2S compositing
Thermoelectric enhancement for n-type PbS via synergistic effect of Ti doping and Cu2S compositing
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Ti掺杂与Cu2S复合协同效应对n型PbS的热电增强
DOI：
10.1063/5.0130364
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发表时间：
2023-01
影响因子：
4
通讯作者：
Ang Ran
中科院分区：
文献类型：
--
作者：
Gan Lin;Zhang Fujie;Zhao Xuanwei;Zhong Yan;Deng Qian;Zhang Kun;Ang Ran
由于PbS与PbTe在晶体结构和能带结构上的相似性，PbS被确定为热电发电和制冷的潜在替代候选材料。但是，由于其电子结构较差和晶格热导率较高，热电性能已达到瓶颈。本工作的重点是优化电子-声子输运的协同效应的Ti和Cu 2S的n型PbS。第一性原理计算、单Kane带模型和Debye模型揭示了热电增强的物理根源。Ti掺杂引入施主-缺陷态，导致高电导率和双极扩散的抑制。然而，由于Ti共振杂质态的局域化效应，PbS的能带结构并不是理想的优化。此外，共同添加的Cu 2S诱导额外的点缺陷，多尺度的第二相，和富铜沉淀物在晶界，显着散射声子在一个很宽的频率范围内，降低晶格热导率。结果表明，n型Pb0.99Ti0.01S-2%Cu2S在823 K时zT最大值为0.8，在300 ~ 623 K范围内zTave平均值为0.46，表明Ti和Cu 2S对改善n型PbS的热电性能具有重要作用.
PbS is identified as a potential alternative candidate material for thermoelectric power generation and refrigeration, owing to the resemblance with PbTe in crystal and band structures. However, the thermoelectric performance has reached a bottleneck because of its inferior electronic structure and high lattice thermal conductivity. This work focuses on optimizing the electron–phonon transport by the synergistic effect of Ti and Cu2S in n-type PbS. The first-principles calculation, single Kane band model, and Debye model reveal the physical origin of thermoelectric enhancement. The Ti doping introduces a donor-defect state, leading to a high electrical conductivity and a suppression of bipolar diffusion. However, the band structure of PbS is not ideally optimized due to the localization effect of the Ti resonant impurity states. Furthermore, the co-added Cu2S induces additional point defects, multiscale secondary phases, and Cu-rich precipitates at grain boundaries, which significantly scatter phonons in a wide frequency range and reduce the lattice thermal conductivity. As a result, the maximum zT of ∼0.8 at 823 K and the average zTave of ∼0.46 from 300 to 623 K are achieved in n-type Pb0.99Ti0.01S–2%Cu2S, demonstrating the important roles of Ti and Cu2S on improving thermoelectrics in n-type PbS.
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