Hierarchical Architectural Structures Induce High Performance in n‐Type GeTe‐Based Thermoelectrics

• DOI: 10.1002/adfm.202213040
• Publication Date: 2023-01-06T07:18:59Z
• Authors: De‐Zhuang Wang; Wei‐Di Liu; Meng Li; Kun Zheng; Hanwen Hu; Liang‐Cao Yin; Yifeng Wang; He Zhu; Xiao‐Lei Shi; Xiaoning Yang; Qingfeng Liu; Zhi‐Gang Chen
• Keywords: n-type GeTe; figure of merit; 540; thermoelectrics; 01 natural sciences; 7. Clean energy; devices; 620; 0104 chemical sciences

AbstractCompatible p‐ and n‐type materials are necessary for high‐performance GeTe thermoelectric modules, where the n‐type counterparts are in urgent need. Here, it is reported that the p‐type GeTe can be tuned into n‐type by decreasing the formation energy of Te vacancies via AgBiTe2 alloying. AgBiTe2 alloying induces Ag2Te precipitates and tunes the carrier concentration close to the optimal level, leading to a high‐power factor of 6.2 µW cm−1 K−2 at 423 K. Particularly, the observed hierarchical architectural structures, including phase boundaries, nano‐precipitates, and point defects, contribute an ultralow lattice thermal conductivity of 0.39 W m−1 K−1 at 423 K. Correspondingly, an increased ZT of 0.5 at 423 K is observed in n‐type (GeTe)0.45(AgBiTe2)0.55. Furthermore, a single‐leg module demonstrates a maximum η of 6.6% at the temperature range from 300 to 500 K. This study indicates that AgBiTe2 alloying can successfully turn GeTe into n‐type with simultaneously optimized thermoelectric performance.