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Alloys and Compounds for Thermoelectric and Solar Cell Applications XI: Session IV
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Alloy Phases Committee
Program Organizers: Hsin-Jay Wu, National Chiao Tung University; Sinn-wen Chen, National Tsing Hua University; Franck Gascoin, CNRS Crismat Unicaen; Philippe Jund, Montpellier University; Yoshisato Kimura, Tokyo Institute of Technology; Takao Mori, National Institute For Materials Science; Wan-Ting Chiu, Tokyo Institute of Technology; Chenguang Fu, Zhejiang University

Tuesday 2:30 PM
March 21, 2023
Room: Sapphire A
Location: Hilton

Session Chair: Wan-ting Chiu, Tokyo Institute of Technology; Bo-Chia Chen, National Yang Ming Chiao Tung university

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2:30 PM  Invited
A Tentative of an Initial Materials Specification of the Process Influence on Sulfide-based Ceramics for Enhancing their Thermoelectric Performances: Cedric Bourges¹; Guillaume Lambard¹; Toshiyuki Nishimura¹; Satoshi Ishii¹; Takao Mori¹; ¹National Institute For Materials Science
    The influence of the sulfur off-stoichiometry induced by the process is not well investigated and mostly considered as a ‘negative’ feature that harms the image of sulfide-based ceramics and restricts their applications. In my presentation, I will introduce the initial material specification, that we developed, using the example of a Cu-based sulfide as key materials for the understanding of the process influence on metal-sulfide ceramics. I will evidence that depending to the synthesis and / or densification methods it is possible to control a certain degree of order / disorder in strategic metal-sulfides ceramics for tuning their TE properties. The strong relationship between the process employed and the sulfur off-stoichiometry will be discussed together with its influences on the resulting physico-chemical and electrical/thermal transport properties. A tentative of rationalization of the relationship and mechanism by machine learning will be introduced.

2:50 PM  Invited
Cluster-Based Molybdenum Chalcogenide Compounds for Thermoelectricity. Dream or Reality? A (Partial) Answer from Theory: Jean-Francois Halet¹; ¹Laboratory for Innovative Key Materials and Structures (LINK)
    Since their discovery in the earliest 70's, Chevrel-Sergent phases (MxMo6X8; M = Ag, Sn, Ca, Sr, Ba, Sn, Pb, 3d elements or lanthanides; X = S, Se, or Te; x = 0−4) have been extensively studied, mainly for their superconducting properties, but also for other various applications in magnetic devices, catalysis, batteries or thermoelectricity. Later, some derivative phases were found, containing larger clusters such as Mo9X11 or Mo30X32 resulting from one-dimensional trans-face sharing of Mo6 octahedra. Some of them, such as AgxMo9Se11 (x = 3.6 – 3.8), show outstandingly low lattice thermal conductivity, giving rise to promising thermoelectric properties. With these results in mind, electronic structure and electronic transport DFT calculations were used for the design of new cluster species which could display interesting thermoelectric properties. Some preliminary results will be presented.

3:10 PM  Invited
Enhancing the SnS-Based Solar Cells by Crystallographic Orientation Engineering and Interfacial Band Alignment Using an Eco-friendly Zinc-Tin-Oxide Buffer Layer: Li-Chyong Chen¹; Thi-Thong Ho²; Zi-Liang Yang¹; Fang-Yu Fu¹; Efat Jokar¹; Shaham Quadir²; Kuei-Hsien Chen²; ¹National Taiwan University; ²Academia Sinica
    Tin monosulfide (SnS) is a promising light-harvesting material for environmental-friendly earth-abundant photovoltaics. However, SnS exhibits orthorhombic structure with a highly anisotropic charge transport behavior. Tailoring the crystallographic orientation of the SnS absorber layer plays a critical role in enhancing the transfer of charge carriers and the power conversion efficiency. Moreover, the energy band alignment between SnS and buffer layer remains the key concern in achieving highly efficient SnS-based solar cells. Herein, we demonstrate a facile method of controlling crystal growth orientation and the great potential of a zinc-tin-oxide (ZTO) buffer layer to achieve suitable band alignment at the SnS/buffer layer interface. Particularly, the influence of the Zn-to-Sn ratio in ZTO on cell performance was systematically investigated. The determination of band offsets in the heterostructures by using X-ray photoelectron spectroscopy and cross-sectional scanning tunneling microscopy proved that the appropriate heterojunction was successfully formed with the ZTO with 18% Sn content.

3:30 PM  Invited
Leveraging Additive Manufacturing to Tailor Thermoelectric Device Configuration, Leg Shape, and Transport Properties: Saniya Leblanc¹; ¹George Washington University
    Additive manufacturing enables unprecedented customization of thermoelectric devices at multiple lengths scales – from nanoscale inclusions to macroscale device shape – potentially all with one manufacturing process. We explore the process-structure-property relationship for laser-based additive manufacturing of thermoelectric materials for low and high temperature applications. We determined the process parameters required to form high density parts and characterized the nano-and micro-structural features formed in the printed parts. Simulations of the spatial and temporal temperature gradients during processing were used to determine solidification rates and thus predict grain structure, such as the distribution of equiaxed versus columnar grains; the predicted grain structure was compared to the experimentally observed grain structure. Thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal diffusivity) of printed bulk parts were measured as a function of temperature. The results provide insight about how additive manufacturing can be used to engineer thermoelectric materials and devices at multiple length scales.

3:50 PM Break

4:10 PM  Invited
Spin-mediated Thermal Transport in Low-dimensional Quantum Magnets: Xi Chen¹; ¹University of California, Riverside
    Understanding the microscopic transport mechanisms of spin excitations and phonons in quantum materials is crucial to develop high performance devices for thermal management, energy conversion, and quantum information processing. In this talk, I will present heat transport measurement as a useful tool to probe these quasiparticles in several magnetic materials with unique quasi-low dimensional crystal structures. I will first introduce large spin-mediated thermal conductivity in the antiferromagnetic spin ladder compound Sr14Cu24O41 and spin chain compound Ca2CuO3. Thermal measurements on bulk single crystals can reveal the elusive coupling of spins with impurities and phonons in these low-dimensional magnets. I will also discuss the synthesis and thermal transport properties of spin ladder microrods and nanostructured polycrystals. It is found that boundary and defect scattering processes are critical for the magnon thermal transport in the microstructures. These findings offer new insights important for devising more efficient devices based on spin transport.

4:30 PM  Invited
Manipulation of Bi-doping of Polycrystalline Ni-Mn-Ga and Fabrication of Grain Particles for Smart Ni-Mn-Ga/polymer Composites: Wan-Ting Chiu¹; Pimpet Sratong-On²; Masaki Tahara¹; Volodymyr Chernenko³; Hideki Hosoda¹; ¹Tokyo Institute of Technology; ²Thai-Nichi Institute of Technology; ³UPV/EHU Science Park
    Actuators are critical components in future technologies, such as robots. Ferromagnetic shape memory alloys, especially the prototype NiMnGa alloys with a Heusler structure, which performs giant deformation strains via applying a magnetic field, are promising materials. In this work, we study how Bi-doping influences the microstructures of the NiMnGa polycrystals and the properties of single-crystalline NiMnGa grain particles obtained by a well-controlled mechanical crushing technique from the polycrystals. Phase constituents, surface morphologies, chemical composition, grain size distributions, thermal properties, and interfacial properties of the NiMnGa-xBi (x = 0.00-0.05 at.%) alloys have been investigated. Furthermore, 20 vol.% of the optimized NiMnGa-0.03Bi single-crystalline particles were homogeneously distributed in a silicone polymer. The composite, which was elastically compressed up to 50% whereby exhibiting a large and reversible deformation strain of the embedded individual single-crystal particles, was in-situ measured by an X-ray micro-CT.

4:50 PM  
Stability Study of Cesium-based Triple Cation Perovskite Solar Cells in Elevated Environmental Ambients: Sujan Aryal¹; Anupama Kaul¹; Mahdi Temsal¹; Ehsan Ghavaminia¹; ¹University of North Texas
    For the hybrid organic-inorganic systems, cesium-based triple cation perovskite solar cells (Cs₀.₀₅FA₀.₇₉MA₀.₁₆PbI₂.₄₅Br₀.₅₅) have recently received a great deal of attention in view of their greater stability compared to the historically significant methyl ammonium lead iodide (MAPbI3) absorber, given the vulnerability of the latter to moisture, oxygen, and ultraviolet radiation. In this work, we have studied the long-term stability of Cs₀.₀₅FA₀.₇₉MA₀.₁₆PbI₂.₄₅Br₀.₅₅ under various stress conditions to accelerate degradation which provide clues into enhancing their stability further. The cesium-based triple cation absorber is integrated into the n-i-p solar cell architecture with gold as the collector electrode, and the stability was gauged using in-use testing with maximum power point tracking, as well as in elevated thermal ambients.

5:10 PM Concluding Comments

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