Pressure-induced enhancement of thermoelectric power factor in pristine and hole-doped SnSe crystals

Abstract

The thermoelectric power factor of SnSe is enhanced by three times under a hydrostatic pressure of 22.5 kbar.

Giant Room‐Temperature Power Factor inp‐Type Thermoelectric SnSe under High Pressure

“…[53] The maximum power factor achieved in our study for the first pressurization cycle at 5 GPa amounted to about 45-60 μW cm −1 K −2 (Figure 3e). This value was approximately the same as the record values of ≈40-55 μW cm −1 K −2 , reported to date for p-doped SnSe crystals at 300 K. [18,[36][37][38][39] For the second and third pressurization cycles, the much higher values of PF ≈ 130-180 μW cm −1 K −2 were attained (Figure 3e).…”

“…Above ≈2 GPa, our curves well coincided with data from the literature for p-doped single crystals having hole concentrations in the range of 10 18 -10 20 cm −3 (Figure 3d), obtained at room temperature both at ambient pressure, [18,34,35] and at high pressure. [39] Thus, the first pressurization cycle in our study, to some extent, corresponded to a charge-carrier optimization via the band-gap narrowing. Previous works found that the thermoelectric performance of SnSe is optimized at 300 K at hole concentrations of an order of 10 19 -10 20 cm −3 .…”

“…The sample deformation mostly modified the contributions of both the band-gap narrowing and the Lifshitz transition. For comparison, data from the literature, [35,39] are given in (b). c) "Thermoelectric phase diagram" of SnSe at 295 K in a form of "electrical resistivity versus thermopower" parametric dependencies for different sorts of samples.…”

Spectroscopic trace of the Lifshitz transition and multivalley activation in thermoelectric SnSe under high pressure

“…At 0.86 GPa, the compound transforms from a two-valley system to a four-valley system, accompanied by improved thermoelectric properties, providing proof that pressure is a powerful tool to tune the electronic multivalley 27,28 . Densityfunctional theory (DFT) calculations and transport studies have reported enhanced thermoelectric properties of SnSe upon application of external pressure [29][30][31][32] . Although transport measurements 33,34 and theoretical approaches 35,36 provide evidence for a semiconductor-semimetal transition, direct investigations of the electronic structure and its pressure dependence are still lacking.…”

High-Pressure Synthesis of Superconducting Sn3S4 Using a Diamond Anvil Cell with a Boron-Doped Diamond Heater

“…Modification of crystal and electronic structures by applying external fields, such as electric field and pressure, reveals the hidden functionalities in materials. Binary tin chalcogenides SnxChy (Ch = S,Se) exhibit various functionalities under the external fields, for example, enhancement of thermoelectric performance 1,2 , appearance of topological Dirac line node 3 , and superconductivity [4][5][6] .…”