Thermoelectric properties of SnSe nanowires with different diameters

Abstract

Tin selenide (SnSe) has been the subject of great attention in the last years due to its highly efficient thermoelectricity and its possibilities as a green material, free of Pb and Te. Here, we report for the first time a thermoelectricity and transport study of individual SnSe micro- and nano-wires with diameters in the range between 130 nm and 1.15 μm. X-ray diffraction and transmission electron microscopy analyses confirm an orthorhombic SnSe structure with Pnma (62) symmetry group and 1:1 Sn:Se atomic ratio. Electrical and thermal conductivity and the Seebeck coefficient were measured in each individual nanowire using a specialized suspended microdevice in the 150–370 K temperature range, yielding a thermal conductivity of 0.55 Wm−1 K−1 at room temperature and ZT ~ 0.156 at 370 K for the 130 nm diameter nanowire. The measured properties were correlated with electronic information obtained by model simulations and with phonon scattering analysis. The results confirm these structures as promising building blocks to develop efficient temperature sensors, refrigerators and thermoelectric energy converters. The thermoelectric response of the nanowires is compared with recent reports on crystalline, polycrystalline and layered bulk structures.

Lattice thermal conductivity of Bi2Te3 and SnSe using Debye-Callaway and Monte Carlo phonon transport modeling: Application to nanofilms and nanowires

“…Along the b and c axes, the evolution of k is similar. When compared to the recent experimental results provided by Hernandez et al [64] for nanowires oriented along the [111] direction we can notice a good agreement of the effective thermal conductivity computed with the Wiener's lower and upper bounds in a large diameter range. In the latter comparison, effective thermal conductivities are obtained combining MC results along the a, b, and c axes.…”

“…For SnSe literature concerning nanostructures thermal properties measurement is much less abundant, especially in what concerns nanofilms. In the next section we will show that some measurements were recently done on nanowires [64]. However, in the frame of the current modeling it is interesting to address this issue and try to be predictive in what concerns thermal conductivity reduction when SnSe film thickness is decreased.…”

“…Such nanostructures appear to be more efficient for thermoelectric purposes as they induce more phonon confinement than nanofilms and thus larger TC reduction. In addition, nanowire elaboration can be easier to achieve using processes that rely on electrochemical growth in porous matrices (alumina or polymer) [22] or direct catalyst-assisted growth [64]. In Fig.…”

“…. SnSe nanowire thermal conductivity along -X (a axis), -Y (b axis), and -Z (c axis) at T = 300 K. Comparison to experimental data by Hernandez et al[64] in the [111] direction. The gray shaded area corresponds to the lower and upper bounds of the Wiener's model of effective thermal conductivity.…”

Thermoelectric Properties of InA Nanowires from Full-Band Atomistic Simulations

“…Significant increases in TE performance and ZT in NWs and their networks have been reported [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. ZT values up to 1 for NWs based on several materials (Si, SiGe, InAs, InSb, Bi, PbTe, ZnO, SnSe, NiFe, and many more) have been investigated [ 11 , 14 , 15 , 16 ]. Since the pioneering work by Hicks and Dresselhaus, efforts have also been focused on utilizing the sharp features in the low-dimensional density-of-states to improve the power factor as well [ 17 , 18 ].…”