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arXiv · 1405.2836

Enhanced Thermoelectric Efficiency via Orthogonal Electrical and Thermal Conductances in Phosphorene

Ruixiang Fei·Alireza Faghaninia·Ryan Soklaski·Jia-An Yan·Cynthia Lo·Li Yang
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Abstract

Thermoelectric devices that utilize the Seebeck effect convert heat flow into electrical energy and are highly desirable for the development of portable, solid state, passively-powered electronic systems. The conversion efficiencies of such devices are quantified by the dimensionless thermoelectric figure of merit (ZT), which is proportional to the ratio of a device's electrical conductance to its thermal conductance. High ZT (>2) has been achieved in materials via all-scale hierarchical architecturing. This efficiency holds at high temperatures (700K~900K) but quickly diminishes at lower temperatures. In this paper, a recently-fabricated two-dimensional (2D) semiconductor called phosphorene (monolayer black phosphorus) is assessed for its thermoelectric capabilities. First-principles and model calculations reveal that phosphorene possesses spatially-anisotropic electrical and thermal conductances. The prominent electrical and thermal conducting directions are orthogonal to one another, enhancing the ratio of these conductances. As a result, ZT can reach 2.5 (the criterion for commercial deployment) along the armchair direction of phosphorene at T=500K and is greater than 1 even at room temperature given moderate doping (~2 x 10^16 m-2). Ultimately, phosphorene stands out as an environmentally sound thermoelectric material with unprecedented qualities: intrinsically, it is a mechanically flexible material that converts heat energy with high efficiency at low temperatures (~ 300K) - one whose performance does not require any sophisticated engineering techniques.

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Ruixiang Fei, Alireza Faghaninia, Ryan Soklaski, Jia-An Yan, Cynthia Lo, Li Yang. 2014-05-12. Enhanced Thermoelectric Efficiency via Orthogonal Electrical and Thermal Conductances in Phosphorene. https://doi.org/10.1021/nl502865s

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