Giant Room‐Temperature Power Factor in p‐Type Thermoelectric SnSe under High Pressure. Issue 20 (20th February 2022)

• Record Type: Journal Article
• Authors: Morozova, Natalia V.; Korobeynikov, Igor V.; Miyajima, Nobuyoshi; Ovsyannikov, Sergey V.
• Is Part Of: Advanced science. Volume 9:Issue 20(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-20
• Subjects: electrical resistivity -- high pressure -- SnSe -- transmission electron microscopy -- thermoelectric power; Science -- Periodicals; 505
• DOI: 10.1002/advs.202103720
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: Materials that can efficiently convert heat into electricity are widely utilized in energy conversion technologies. The existing thermoelectrics demonstrate rather limited performance characteristics at room temperature, and hence, alternative materials and approaches are very much in demand. Here, it is experimentally shown that manipulating an applied stress can greatly improve a thermoelectric power factor of layered p ‐type SnSe single crystals up to ≈180 µW K −2 cm −1 at room temperature. This giant enhancement is explained by a synergetic effect of three factors, such as: band‐gap narrowing, Lifshitz transition, and strong sample deformation. Under applied pressure above 1 GPa, the SnSe crystals become more ductile, which can be related to changes in the prevailing chemical bonding type inside the layers, from covalent toward metavalent. Thus, the SnSe single crystals transform into a highly unconventional crystalline state in which their layered crystal stacking is largely preserved, while the layers themselves are strongly deformed. This results in a dramatic narrowing in a band gap, from E g = 0.83 to 0.50 eV (at ambient conditions). Thus, the work demonstrates a novel strategy of improving the performance parameters of chalcogenide thermoelectrics via tuning their chemical bonding type, stimulating a sample deformation and a band‐structure reconstruction. Abstract : In the example of p ‐type SnSe, a novel strategy of improving the thermoelectric performance of chalcogenide thermoelectrics via tuning their chemical bonding type, is demonstrated. Under applied high pressure, the SnSe crystals are severe deformed and their band structure is dramatically modified. This results in a colossal enhancement of their thermoelectric power factors at room temperature.