Strain effects on thermoelectric properties of two-dimensional materials

Two-dimensional (2D) materials, such as graphene, hexagonal boron nitride (hBN), phosphorene, transition metal dichalcogenides (e.g., MOS2, WS2, etc.), metal oxides (e.g., MoO3) have attracted much attention recently due to their extraordinary structural, mechanical and physical properties. In particular, 2D materials have shown great potential for thermal management and thermoelectric energy generation due to their fascinating electrical and thermal transport properties, which can lead to a significantly large figure-of-merit. Also due to their large stretchability, 2D materials are promising for using strain engineering to tune and modulate their electronic and thermal properties, which can further enhance their figure-of-merit. In this article, we give a review on the recent advances in the study of strain-engineering on the thermoelectric properties of 2D materials. We first review some important aspects in thermoelectric effects, such as Peltier effect, Seebeck effect, the coefficient of performance and figure-of-merit (ZT) and discuss why 2D materials are ideal candidates for thermal management and thermoelectric applications. We then briefly discuss the strain (stress) generation in 2D materials and their structure integrity under strain (stress). Next, we discuss how strain affects the electronic properties of 20 materials, followed by the discussion on the effects of strain on the thermal properties of 2D materials. Subsequently, we discuss the strain effects on two important thermoelectric properties, Seebeck coefficient and figure-of-merit Zr. Finally, we present our conclusions and future perspective. (C) 2015 Elsevier Ltd. All rights reserved.