Discovery of novel high-performance materials with earth-abundant and environmentally friendly elements is a key task for civil applications based on advanced thermoelectric technology. Advancements in this area are greatly limited by the traditional trial-and-error method, which is both time-consuming and expensive. The materials genome initiative can provide a powerful strategy to screen for potential novel materials using high-throughput calculations, materials characterization, and synthesis. In this study, we developed a modified diffusion-couple high-throughput synthesis method and an automated histogram analysis technique to quickly screen high-performance copper chalcogenide thermoelectric materials, which has been well demonstrated in the ternary Cu–Sn–S compounds. A new copper chalcogenide with the composition of Cu 7 Sn 3 S 10 was discovered. Studies on crystal structure, band gap, and electrical and thermal transport properties were performed to show that it is a promising thermoelectric material with ultralow lattice thermal conductivity, moderate band gap, and decent electrical conductivity. Via Cl doping, the thermoelectric dimensionless figure of merit zT reaches 0.8 at 750 K, being among the highest values reported in Cu–Sn–S ternary materials. The modified diffusion-couple high-throughput synthesis method and automated histogram analysis technique developed in this study also shed light on the development of other advanced thermoelectric andmore »
Synthetic versatility, reaction pathway, and thermal stability of tetrahedrite nanoparticles
Copper-antimony-sulfide compounds have desirable earth-abundant compositions for application in renewable energy technologies, such as solar energy and waste heat recycling. These compounds can be synthesized by bottom-up, solution-phase techniques that are more energy and time efficient than conventional solid-state methods. Solution-phase methods typically produce nanostructured materials, which adds another dimension to control optical, electrical, and thermal material properties. This study focuses on a modified-polyol, solution-phase synthesis for tetrahedrite (Cu 12 Sb 4 S 13 ), a promising thermoelectric material with potential also for photovoltaic applications. To dope the tetrahedrite and tune material properties, the utility of the modified polyol synthetic approach has been demonstrated as a strategy to produce phase-pure tetrahedrite that incorporates transition metal (Fe, Co, Ni, Zn, Ag) dopants for Cu, Te dopant for Sb, and Se for S. Six of these reported tetrahedrite compounds have not previously been made by solution-phase methods. For the bottom-up formation of the tetrahedrite nanomaterials, the evolution of the chemical phases has been determined by an investigation of the reaction progress as a function of temperature and time. Digenite (Cu 1.8 S), covellite (CuS), and famatinite (Cu 3 SbS 4 ) are identified as key intermediates and are consistently observed for both more »
- Publication Date:
- NSF-PAR ID:
- 10228939
- Journal Name:
- Journal of Materials Chemistry C
- Volume:
- 8
- Issue:
- 40
- Page Range or eLocation-ID:
- 14219 to 14229
- ISSN:
- 2050-7526
- Sponsoring Org:
- National Science Foundation
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There has been a growing interest in solution-phase routes to thermoelectric materials due to the decreased costs and novel device architectures that these methods enable. Many excellent thermoelectric materials are metal chalcogenide semiconductors and the ability to create soluble metal chalcogenide semiconductor precursors using thiol–amine solvent mixtures was recently demonstrated by others. In this paper, we report the first thermoelectric property measurements on metal chalcogenide thin films made in this manner. We create Cu 2−x Se y S 1−y and Ag-doped Cu 2−x Se y S 1−y thin films and study the interrelationship between their composition and room temperature thermoelectric properties. We find that the precursor annealing temperature affects the metal : chalcogen ratio, and leads to charge carrier concentration changes that affect the Seebeck coefficient and electrical conductivity. Increasing the Se : S ratio increases electrical conductivity and decreases the Seebeck coefficient. We also find that incorporating Ag into the Cu 2−x Se y S 1−y film leads to appreciable improvements in thermoelectric performance by increasing the Seebeck coefficient and decreasing thermal conductivity. Overall, we find that the room temperature thermoelectric properties of these solution-processed materials are comparable to measurements on Cu 2−x Se alloys made via conventional thermoelectric material processing methods. Achievingmore »
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Abstract Earth-abundant antimony trisulfide (Sb2S3), or simply antimonite, is a promising material for capturing natural energies like solar power and heat flux. The layered structure, held up by weak van-der Waals forces, induces anisotropic behaviors in carrier transportation and thermal expansion. Here, we used stress as mechanical stimuli to destabilize the layered structure and observed the structural phase transition to a three-dimensional (3D) structure. We combined in situ x-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible spectroscopy, and first-principles calculations to study the evolution of structure and bandgap width up to 20.1 GPa. The optical band gap energy of Sb2S3followed a two-step hierarchical sequence at approximately 4 and 11 GPa. We also revealed that the first step of change is mainly caused by the redistribution of band states near the conduction band maximum. The second transition is controlled by an isostructural phase transition, with collapsed layers and the formation of a higher coordinated bulky structure. The band gap reduced from 1.73 eV at ambient to 0.68 eV at 15 GPa, making it a promising thermoelectric material under high pressure.
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Abstract Two-dimensional (2D) ternary materials recently generated interest in optoelectronics and energy-related applications, alongside their binary counterparts. To date, only a few naturally occurring layered 2D ternary materials have been explored. The plethora of benefits owed to reduced dimensionality prompted exploration of expanding non-layered ternary chalcogenides into the 2D realm. This work presents a templating method that uses 2D transition metal dichalcogenides as initiators to be converted into the corresponding ternary chalcogenide upon addition of copper, via a solution-phase synthesis, conducted in high boiling point solvents. The process starts with preparation of VSe2nanosheets, which are next converted into Cu3VSe4sulvanite nanosheets (NSs) which retain the 2D geometry while presenting an X-ray diffraction pattern identical with the one for the bulk Cu3VSe4. Both the scanning electron microscopy and transmission microscopy electron microscopy show the presence of quasi-2D morphology. Recent studies of the sulfur-containing sulvanite Cu3VS4highlight the presence of an intermediate bandgap, associated with enhanced photovoltaic (PV) performance. The Cu3VSe4nanosheets reported herein exhibit multiple UV–Vis absorption peaks, related to the intermediate bandgaps similar to Cu3VS4and Cu3VSe4nanocrystals. To test the potential of Cu3VSe4NSs as an absorber for solar photovoltaic devices, Cu3VSe4NSs thin-films deposited on FTO were subjected to photoelectrochemical testing, showing p-type behavior andmore »
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Low-cost materials, scalable manufacturing, and high power conversion efficiency are critical enablers for large-scale applications of photovoltaic (PV) cells. Cu 2 ZnSn(S,Se) 4 (CZTSSe) has emerged as a promising PV material due to its low-cost earth-abundant nature and the low toxicity of its constituents. We present a compact and environmentally friendly route for preparing metal sulfide (metals are Cu, Zn, and Sn) nanoparticles (NPs) and optimize their annealing conditions to obtain uniform carbon-free CZTSSe thin films with large grain sizes. Further, the solution-stable binary NP inks synthesized in an aqueous solution with additives are shown to inhibit the formation of secondary phases during annealing. A laboratory-scale PV cell with a Al/AZO/ZnO/CdS/CZTSSe/Mo-glass structure is fabricated without anti-reflective coatings, and a 9.08% efficiency under AM1.5G illumination is demonstrated for the first time. The developed scalable, energy-efficient, and environmentally sustainable NP synthesis approach can enable integration of NP synthesis with emerging large-area deposition and annealing methods for scalable fabrication of CZTSSe PV cells.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1039/d0tc03599h
