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Atomically Thick Bismuth Selenide Freestanding Single Layers Achieving Enhanced Thermoelectric Energy Harvesting
- Sun, Yongfu, Cheng, Hao, Gao, Shan, Liu, Qinghua, Sun, Zhihu, Xiao, Chong, Wu, Changzheng, Wei, Shiqiang, Xie, Yi
- Journal of the American Chemical Society 2012 v.134 no.50 pp. 20294-20297
- X-ray absorption spectroscopy, bismuth, electrical conductivity, electricity, energy, energy conservation, heat, thermal conductivity, wastes
- 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 Bi₂Se₃ 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 Bi₂Se₃ 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.