Efficient interlayer charge release for high-performance layered thermoelectrics

• 来源期刊: 国家科学评论（英文版）
• 年，卷（期）: 2021,（2）
• 所属期刊栏目: RESEARCH ARTICLES
• 页码范围: 110-117
• 页数: 8页
• 语种: 英文
• DOI: 10.1093/nsr/nwaa085

摘要

Many layered superlattice materials intrinsically possess large Seebeck coefficient and low lattice thermal conductivity,but poor electrical conductivity because of the interlayer transport barrier for charges,which has become a stumbling block for achieving high thermoelectric performance.Herein,taking BiCuSeO superlattice as an example,it is demonstrated that efficient interlayer charge release can increase carrier concentration,thereby activating multiple Fermi pockets through Bi/Cu dual vacancies and Pb codoping.Experimental results reveal that the extrinsic charges,which are introduced by Pb and initially trapped in the charge-reservoir[Bi2C2]2+sublayers,are effectively released into[Cu2Se2]2-sublayers via the channels bridged by Bi/Cu dual vacancies.This efficient interlayer charge release endows dual-vacancy-and Pb-codoped BiCuSeO with increased carrier concentration and electrical conductivity.Moreover,with increasing carrier concentration,the Fermi level is pushed down,activating multiple converged valence bands,which helps to maintain a relatively high Seebeck coefficient and yield an enhanced power factor.As a result,a high ZT value of～1.4 is achieved at 823 K in codoped Bi0.90Pb0.06Cu0.96SeO,which is superior to that of pristine BiCuSeO and solely doped samples.The present findings provide prospective insights into the exploration of high-performance thermoelectric materials and the underlying transport physics.