High thermoelectric energy conversion efficiency requires a large figure-of-merit, zT, over a broad temperature range. To achieve this, we optimize the carrier concentrations of n-type PbTe from room up to hot-end temperatures by co-doping Bi and Ag. Bi is an efficient n-type dopant in PbTe, often leading to excessive carrier concentration at room temperature. As revealed by density functional theory calculations, the formation of Bi and Ag defect complexes is exploited to optimize the room temperature carrier concentration. At elevated temperatures, we demonstrate the dynamic dissolution of Ag₂Te precipitates in PbTe in situ by heating in a scanning transmission electron microscope. The release of n-type Ag interstitials with increasing temperature fulfills the requirement of higher carrier concentrations at the hot end. Moreover, as characterized by atom probe tomography, Ag atoms aggregate along parallel dislocation arrays to form Cottrell atmospheres. This results in enhanced phonon scattering and leads to a low lattice thermal conductivity. As a result of the synergy of dynamic doping and phonon scattering at decorated dislocations, an average zT of 1.0 is achieved in n-type Bi/Ag-codoped PbTe between 400 and 825 K. Introducing dopants with temperature-dependent solubility and strong interaction with dislocation cores enables simultaneous optimization of the average power factor and thermal conductivity, providing a new concept to exploit in the field of thermoelectrics.

高热电能量转换效率需要在较宽的温度范围内具有较大的品质因数zT 。为了实现这一点，我们通过共掺杂 Bi 和 Ag 来优化从室温到热端温度的 n 型 PbTe 的载流子浓度。Bi 是 PbTe 中的一种有效 n 型掺杂剂，通常会导致室温下的载流子浓度过高。正如密度泛函理论计算所揭示的那样，利用 Bi 和 Ag 缺陷复合物的形成来优化室温载流子浓度。在高温下，我们展示了 Ag _{2的动态溶解}通过在扫描透射电子显微镜中加热，Te 在 PbTe 中原位沉淀。随着温度升高，n 型 Ag 间隙原子的释放满足了热端更高载流子浓度的要求。此外，如原子探针断层扫描所表征的那样，Ag 原子沿平行位错阵列聚集形成 Cottrell 气氛。这导致声子散射增强并导致晶格热导率低。由于动态掺杂和声子散射在修饰位错处的协同作用，平均zT在 400 和 825 K 之间的 n 型 Bi/Ag 共掺杂 PbTe 中实现了 1.0。引入具有温度依赖性溶解度和与位错核心强相互作用的掺杂剂可以同时优化平均功率因数和热导率，为热电领域的发展。