title: Atomically thick bismuth selenide freestanding single layers achieving enhanced thermoelectric energy harvesting.
abstract: Thermoelectric materials can realize significant energy savings by generating electricity from untapped waste heat. However, the coupling of the thermoelectric parameters unfortunately limits their efficiency and practical applications. Here, a single-layer-based (SLB) composite fabricated from atomically thick single layers was proposed to optimize the thermoelectric parameters fully. Freestanding five-atom-thick Bi(2)Se(3) single layers were first synthesized via a scalable interaction/exfoliation strategy. As revealed by X-ray absorption fine structure spectroscopy and first-principles calculations, surface distortion gives them excellent structural stability and a much increased density of states, resulting in a 2-fold higher electrical conductivity relative to the bulk material. Also, the surface disorder and numerous interfaces in the Bi(2)Se(3) SLB composite allow for effective phonon scattering and decreased thermal conductivity, while the 2D electron gas and energy filtering effect increase the Seebeck coefficient, resulting in an 8-fold higher figure of merit (ZT) relative to the bulk material. This work develops a facile strategy for synthesizing atomically thick single layers and demonstrates their superior ability to optimize the thermoelectric energy harvesting.
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, PR China.
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Sun
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Liu
authors.forename: Zhihu
authors.initials: Z
authors.lastname: Sun
authors.forename: Chong
authors.initials: C
authors.lastname: Xiao
authors.forename: Changzheng
authors.initials: C
authors.lastname: Wu
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D004560:Electricity; D006358:Hot Temperature; D056928:X-Ray Absorption Spectroscopy / Q000379:methods*
chemical_list: D001729:Bismuth