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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Modulating the Electronic Transport of 2D Sb2Te3 Nanoplates by Coinage Metal Intercalation

Thermoelectric materials are particularly relevant to the current energy infrastructure and demands of the 21st century, converting waste heat into usable electricity. The solution intercalation of zerovalent copper into Sb2Te3 nanoplates, a well-established thermoelectric material, is reported. The copper intercalant is homogeneously distributed throughout the nanoplates, confirmed by scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. The copper composition was shown to be 6 at. % by X-ray photoelectron spectroscopy. Copper ordering within the van der Waals gaps of the nanoplates is confirmed by selected area electron diffraction. Fabrication and thermoelectric property measurements of single-crystal Sb2Te3 and Cu-Sb2Te3 nanoplate devices show effective modulation of electrical conductivity and Seebeck coefficient with Cu intercalation. X-ray photoelectron spectroscopic studies in the valence-band region reveal additional electronic states from copper that appear near the Fermi energy, postulated to act as electron acceptors, leading to modulation of the electronic transport properties.

2D nanoplates↗
DOE OSTI2020

Materials Data on Sb2Te3 by Materials Project

Sb2Te3 is MAX Phase-derived structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three Sb2Te3 sheets oriented in the (0, 0, 1) direction. Sb3+ is bonded to six Te2- atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.03 Å) and three longer (3.19 Å) Sb–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to six equivalent Sb3+ atoms to form edge-sharing TeSb6 octahedra. In the second Te2- site, Te2- is bonded in a 3-coordinate geometry to three equivalent Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sb2Te3 by Materials Project

Sb2Te3 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Sb3+ is bonded in a linear geometry to two Te2- atoms. There are one shorter (2.90 Å) and one longer (3.17 Å) Sb–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to two equivalent Sb3+ and six equivalent Te2- atoms to form a mixture of edge and corner-sharing TeSb2Te6 hexagonal bipyramids. All Te–Te bond lengths are 3.39 Å. In the second Te2- site, Te2- is bonded to one Sb3+ and seven equivalent Te2- atoms to form distorted TeSbTe7 hexagonal bipyramids that share corners with seven TeSb2Te6 hexagonal bipyramids and edges with eighteen equivalent TeSbTe7 hexagonal bipyramids. There are six shorter (3.39 Å) and one longer (3.48 Å) Te–Te bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbTe by Materials Project

SbTe crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Sb sheet oriented in the (0, 0, 1) direction and two Sb2Te3 sheets oriented in the (0, 0, 1) direction. In the Sb sheet, Sb is bonded in a 3-coordinate geometry to three equivalent Sb atoms. All Sb–Sb bond lengths are 2.95 Å. In each Sb2Te3 sheet, there are two inequivalent Sb sites. In the first Sb site, Sb is bonded to six Te atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.03 Å) and three longer (3.20 Å) Sb–Te bond lengths. In the second Sb site, Sb is bonded to six Te atoms to form a mixture of edge and corner-sharing SbTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (3.04 Å) and three longer (3.19 Å) Sb–Te bond lengths. There are three inequivalent Te sites. In the first Te site, Te is bonded in a distorted T-shaped geometry to three equivalent Sb atoms. In the second Te site, Te is bonded to six Sb atoms to form edge-sharing TeSb6 octahedra. In the third Te site, Te is bonded in a 3-coordinate geometry to three equivalent Sb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Antimony Chloride Treatments of CdTe-Based Solar Cells

Development of a new SbCl3-based solution treatment for chloride activation of CdTe-based solar cells is described. Activation was confirmed with CdSeTe:Sb devices exhibiting VOC > 550 mV and JSC > 25 mAcm-2. Treatment optimization showed strong effects of annealing time and temperature on cell properties. Material characterization indicated surface conversion of CdSeTe to CdCl2 and Sb2Te3 with SbCl3 treatment. However, no reaction products were formed with treatment under inert conditions, which was coupled with poor device performance. Drying the SbCl3 films at controlled humidity conditions confirmed that exposure to high relative humidity is critical for CdSeTe activation, through hydrolysis of SbCl3. Mechanistic details of SbCl3 speciation during hydrolysis and annealing to activate CdSeTe are discussed.

14 SOLAR ENERGY↗
DOE OSTI2024

Thermally induced structural evolution and nanoscale interfacial dynamics in Bi-Sb-Te layered nanostructures

Layered chalcogenides, including Bi-Sb-Te ternary alloys and heterostructures, are renowned as thermoelectric and topological insulators and have recently been highlighted as plasmonic building blocks beyond noble metals. Here, we conduct joint in situ transmission electron microscopy and density functional theory calculations to investigate the temperature-dependent nanoscale dynamics and interfacial properties, identifying the role of native defects and edge configurations in the anisotropic sublimation of Bi 2 Te 3 -Sb 2 Te 3 heterostructures and Sb 2-x Bi x Te 3 alloys. We report structural dynamics, including edge evolution, layer-by-layer sublimation, and the formation and coalescence of thermally induced polygonal nanopores. These nanopores are initiated by preferential dissociation of tellurium, reducing thermal stability in heterostructures. Triangular and quasi-hexagonal configurations dominate nanopore structures in heterostructures. Our calculations reveal antisite defects (Te Sb and Te Bi ) as key players in defect-assisted sublimation. These findings enhance our understanding of nanoscale dynamics and assist in designing tunable low-dimensional chalcogenides.

Bi2Te3-Sb2Te3 heterostructure↗
DOE OSTI2021

Ex Situ Photoelectron Emission Microscopy of Polycrystalline Bismuth and Antimony Telluride Surfaces Exposed to Ambient Oxidation

The surfaces of textured polycrystalline N-type bismuth telluride and P-type antimony telluride materials were investigated using ex situ photoelectron emission microscopy (PEEM). PEEM enabled imaging of the work function for different oxidation times due to exposure to air across sample surfaces. The spatially averaged work function was also tracked as a function of air exposure time. N-type bismuth telluride showed an increase in the work function around grain boundaries relative to grain interiors during the early stages of air exposure-driven oxidation. At longer time exposure to air, the surface became homogenous after a ~5 nm-thick oxide formed. X-ray photoemission spectroscopy was used to correlate changes in PEEM imaging in real space and work function evolution to the progressive growth of an oxide layer. The observed work function contrast is consistent with the pinning of electronic surface states due to the defects at a grain boundary.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗