Study of Structural, Thermoelectric, and Photoelectric Properties of Layered Tin Monochalcogenides SnX (X = S, Se) for Energy Application

Abstract

SnS and SnSe are renowned energy materials that are applied for photoelectric and thermoelectric conversions owing to their suitable band gap, close to 1 eV, and superior figure of merit (ZT), larger than 0.1. In this paper, high-quality layered SnX (X = S, Se) crystals have been successfully grown by the chemical vapor transport (CVT) method. The crystal structure and band structure of SnX are studied, and their photoelectric and thermoelectric properties are characterized. In Raman measurement, four vibration modes with distinct angle-polarization dependence are simultaneously detected by both SnS and SnSe, verifying their similar orthorhombic layered structure with in-plane anisotropy. In-plane anisotropy of band-edge and interband transitions along a and b axes has also been measured experimentally using polarized thermoreflectance (PTR) from 0.7 to 5 eV. The anisotropic band edges of layered SnX (X = S, Se) are well matched and reproduced by first-principles calculation. Hall-effect and thermoelectric measurements revealed that SnX are p-type semiconductors with a high carrier density, larger than 10 17 cm −3 . According to the measurement results of the surface photovoltaic (SPV) response and ZT value, layered SnS can have a superior SPV (8.5 μV/μW) response ∼12× higher than that of SnSe, while SnSe has a ZT of 0.16, ∼4× larger than that of SnS in SnX (X = S, Se). Layered SnSe and SnS could possess great feasibility for application in thermoelectric power generation and solar energy conversion.

Enhanced Thermoelectric Performance of Tin(II) Sulfide Thin Films Prepared by Aerosol Assisted Chemical Vapor Deposition

“…The interplanar spacings of the diffraction spots 1, 2, and 3 shown in Figure c are approximately 0.211, 0.290, and 0.201 nm, corresponding well to the planes of (2 0 0), (1 0 1), and (0 0 2) respectively. The angles between (2 0 0) and (1 0 1), and between (2 0 0) and (0 0 2) are approximately 46° and 90°; consistent with the XRD analysis and earlier work . The small white spots near the bright spots appear to belong to the other SnS crystals beneath the main crystal in area c of Figure a.…”

Optical and Thermoelectric Properties of Surface-Oxidation Sensitive Layered Zirconium Dichalcogenides ZrS2−xSex (x = 0, 1, 2) Crystals Grown by Chemical Vapor Transport

“…Thermal conductivity κ can be calculated from the heating power and temperature difference ∆T from the sample geometry as P = κ•(w•t/l)•∆T, where w is width, t is thickness, and l is length, respectively. The ZT is an index of efficient thermoelectric material, but ZT value is inversely proportional to thermal conductivity κ [48,49]. Figure 4d shows the ZT values of the ZrS 2−x Se x series from 20 to 300 K. The ZT values of all samples increase when the temperature is increased, while thermal conductivity κ decreases when the temperature is raised (see Figure 4c).…”

2D SnSe Cathode Catalyst Featuring an Efficient Facet‐Dependent Selective Li2O2 Growth/Decomposition for Li–Oxygen Batteries

“…Materials with a 2D layered structure have received considerable attention for use in catalytic, electronic and optoelectronic devices [ 21–24 ] due to their unique properties including a large surface area, [ 25 ] flexible stack layers, [ 26 ] electron confinement effect, [ 27 ] high carrier mobility, and thickness‐tunable bandgap modulation. [ 28 ] Recently, 2D materials were theoretically and experimentally confirmed to possess high catalytic capacity for use as the cathode catalyst in LOBs. For example, a g‐GeC monolayer was predicted to lower the overpotentials during ORR/OER processes.…”

“…[19,20] Materials with a 2D layered structure have received considerable attention for use in catalytic, electronic and optoelectronic devices [21][22][23][24] due to their unique properties including a large surface area, [25] flexible stack layers, [26] electron confinement effect, [27] high carrier mobility, and thickness-tunable bandgap modulation. [28] Recently, 2D materials were theoretically and 2D materials are attracting much attention in the field of cathode catalysts for lithium-oxygen batteries (LOBs) due to their layered structure, unique electronic properties, and high stability. However, different stacking layer structures trigger different catalytic capabilities in LOBs.…”