@article{22734, abstract = {Silver selenide (Ag2Se) is a promising near-room-temperature thermoelectric material, but its narrow stoichiometric window and β–α phase transition complicate reproducible microstructure control. Here, we present a mismatch-assisted microstructure engineering strategy in which Ag2Se particles are treated with polyanionic ZnSe complexes and consolidated through the β–α transition to introduce ZnSe nanoprecipitates, Ag2Se/ZnSe interfaces, and local strain fields. The crystallographic mismatch between ZnSe and Ag2Se, together with the Zn2+/Ag+ size difference, amplifies phase-transition-induced deformation and promotes high-density dislocations with periodic strain modulations. This defect architecture suppresses grain coarsening, removes excess Ag, limits Ag-interstitial formation, and reduces lattice thermal conductivity through lattice softening and multiscale phonon scattering. Ag2Se–4%ZnSe nanocomposites achieve a peak zTmax of 1.13 at 369 K and a zTavg of 1.08 from 300 to 380 K, demonstrating mismatch-driven defect engineering through the β–α phase transition as a route for optimizing Ag2Se-based thermoelectrics.}, author = {Liu, Yu and Kleinhanns, Tobias and Spadaro, Maria Chiara and Genç, Aziz and Horta, Sharona and Navita, Navita and Costanzo, Tommaso and Dutkiewicz, Ewelina and Arbiol, Jordi and Hong, Min and Ibáñez, Maria}, issn = {2380-8195}, journal = {ACS Energy Letters}, number = {8}, pages = {5752--5762}, publisher = {American Chemical Society}, title = {{Exploiting mismatch strain and the β–α phase transition for microstructural engineering in thermoelectric Ag2Se}}, doi = {10.1021/acsenergylett.6c01499}, volume = {11}, year = {2026}, } @article{22712, abstract = {Ginseng (Panax ginseng) derives its renowned therapeutic properties from ginsenoside metabolites. However, the long cultivation cycle and susceptibility to diseases hinder the advancement of the ginseng industry. Here, we demonstrate that the embryonic protoderm of ginseng can efficiently produce ginsenosides. Single-cell transcriptome and mass spectrometry imaging analyses reveal that ginsenosides accumulate in the protoderm of ginseng embryonic callus (EC) at levels comparable to those in forest ginseng. Epigenetic analyses indicate that elevated histone acetylation and enhanced chromatin accessibility at regeneration- and ginsenoside metabolism-related gene loci are associated with the ginsenoside-producing capacity of EC. Increasing histone acetylation levels or overexpressing the regeneration-related WUSCHEL-RELATED HOMEOBOX11 (WOX11) gene further enhances ginsenoside production in EC. Our findings suggest that the protoderm of EC could serve as an in situ biological compartment for high-efficiency ginsenoside producion, offering a complementary approach to traditional ginseng cultivation.}, author = {Liu, Juan and Zhai, Ning and Zhang, Shiyi and Tamada, Yosuke and Li, Tonghui and Zhang, Linfan and Chen, Tong and Wang, Chenglin and Yang, Jian and Gao, Jiaqi and Li, Xiang and Zhou, Junhui and Zhang, Yonghong and Liu, Yu and Wang, Yuan and Friml, Jiří and Benková, Eva and Li, Chen and Xu, Lin and Huang, Luqi}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Single-cell analyses identify the ginseng embryonic protoderm as a native compartment for high-efficiency ginsenoside production}}, doi = {10.1038/s41467-026-74881-5}, volume = {17}, year = {2026}, } @article{22967, abstract = {Alkali salts are widely used in solution processing, yet the corresponding cations are often assumed to remain in the liquid phase. Here, we show that alkali ions introduced during the solution synthesis of SnSe are retained through particle isolation and continue to influence the material during subsequent thermal processing, where they shape the evolution of the final polycrystalline material. Different SnSe powders were prepared using Li+, Na+, and K+ precursors, as well as tetramethylammonium (TMA+) precursors as a nonalkali reference for comparison, and all samples were consolidated under identical conditions. Although all three alkali ions were found in the matrix, at grain boundaries, and in segregated nanoscale regions, they partitioned differently and resulted in distinct grain sizes, defect distributions, and therefore transport properties. Li induced the strongest grain size heterogeneity and the lowest energy barriers, Na the best overall balance between carrier concentration and mobility, and K the broadest alkali-rich grain boundary regions along with the strongest interfacial penalty to charge carrier transport. These results show that residual alkali ions are not just remnants of solution synthesis but active determinants of microstructure and thermoelectric performance in SnSe.}, author = {Fiedler, Christine and Horta, Sharona and Navita, Navita and Maji, Krishnendu and Kleinhanns, Tobias and Llorca, Jordi and Wang, Qi and Ramon, Maria Garcia and Das, Sambit and Gavini, Vikram and Liu, Yu and Ibáñez, Maria}, issn = {1520-5002}, journal = {Chemistry of Materials}, number = {18}, pages = {9323–9332}, publisher = {American Chemical Society}, title = {{Alkali ions retained from synthesis govern microstructure and transport in solution-processed SnSe}}, doi = {10.1021/acs.chemmater.6c01284}, volume = {38}, year = {2026}, } @article{18882, abstract = {Ternary liquid-like thermoelectric materials have garnered significant attention due to their ultra-low lattice thermal conductivity. Among these, Ag8SnSe6 stands out for its exceptionally low sound velocity and thermal conductivity. However, the inherent poor electrical conductivity and suboptimal thermoelectric properties of Ag8SnSe6 necessitate further improvement. Here, a novel approach is initiated to enhance the thermoelectric properties of Ag8SnSe6 by combining low-dimensionalization with intrinsic doping. For the first time, this work successfully synthesizes single-phase Ag8SnSe6 nanocrystals, ≈10 nm in size, with the correct phase and composition using a robust and reliable colloidal method. This approach represents a significant improvement over previous reports on this material. Reducing the crystal domains of Ag8SnSe6 to the nanoscale induces quantum confinement effects, increasing the density of states near the Fermi surface. It also introduces additional grain boundaries, which lower the lattice thermal conductivity and simplify structural design. Moreover, incorporating small amounts of Sn nanopowder into the Ag8SnSe6 nanocrystals before consolidation further enhances the thermoelectric performance. Sn acts as a donor dopant, increasing the electronic concentration while at the same time improving their mobility by reducing interface barriers, thus significantly improving the material transport properties. Additionally, the presence of Sn leads to the formation of point defects, dislocations, and secondary phases, which increase phonon scattering and further reduce the thermal conductivity. Through this synergistic optimization, the figure of merit shows a significant increase across a wide temperature range. Overall, a strategy is presented for the controlled preparation of Ag8SnSe6 nanocrystals, the decoupling of their electrical and thermal transport, and the practical application of this material to thermoelectric single-leg modules.}, author = {Zhao, Xueke and Li, Mengyao and Jia, Mochen and Fiedler, Christine and Nan, Bingfei and Yang, Dongwen and Li, Lei and Yuan, Zicheng and Song, Hongzhang and Liu, Yu and Ibáñez, Maria and Wang, Ziyu and Shan, Chongxin and Cabot, Andreu}, issn = {1616-3028}, journal = {Advanced Functional Materials}, number = {24}, publisher = {Wiley}, title = {{Low-dimensional structure modulation in Ag8SnSe6 for enhanced thermoelectric performance}}, doi = {10.1002/adfm.202421449}, volume = {35}, year = {2025}, } @article{20426, abstract = {SnTe has attracted significant research interest as a lead-free alternative to PbTe; however, its intrinsically high hole concentration results in an undesirably low Seebeck coefficient and elevated electronic thermal conductivity, thus significantly limiting its thermoelectric (TE) performance. Herein, we present a cost-effective, binary thiol-amine-mediated colloidal synthesis method to synthesize Bi-doped SnTe nanoparticles, eliminating the use of tri-n-octylphosphine-based precursors. The introduction of an electron-rich Bi dopant reduces the hole concentration and increases the Seebeck coefficient. Furthermore, post-synthetic surface treatment with chalcogenidocadmate complexes promotes atomic interdiffusion during annealing and consolidation, leading to compositional redistribution and modulation of the electronic band structure. Density functional theory (DFT) calculations reveal that co-modification via Bi doping and CdSe-derived chalcogen incorporation reduces the energy offset at the valence band maxima from 0.30 eV to 0.10 eV, thereby enhancing valence band degeneracy. The synergistic structural and electronic band structure modulations produce an SnTe-based material with a record high power factor of 2.1 mW m–1 K–2 at 900 K, a maximum TE figure of merit (zT) of 1.2, and a promising theoretical conversion efficiency of 8.3%. This study reports a versatile and scalable colloidal synthesis strategy that integrates hierarchical structural modulation with electronic band engineering, offering a synergistic route to significantly enhance the TE performance.}, author = {Meng, Weite and Xu, Lixiang and Lu, Shaoqing and Li, Mingquan and Li, Mengyao and Zhang, Yu and Wang, Qingyue and Wang, Wen Jun and Huo, Siqi and Bañares, Miguel A. and Martin-Gonzalez, Marisol and Ibáñez, Maria and Cabot, Andreu and Hong, Min and Liu, Yu and Lim, Khak Ho}, issn = {1936-086X}, journal = {ACS Nano}, number = {38}, pages = {34395--34407}, publisher = {American Chemical Society}, title = {{Thiol-Amine complexes for the synthesis and surface engineering of SnTe nanomaterials toward high thermoelectric performance}}, doi = {10.1021/acsnano.5c12627}, volume = {19}, year = {2025}, } @article{20326, abstract = {Ag2Se is a promising n-type thermoelectric material, but its performance is limited by excessive carrier concentration, compositional inhomogeneity, and phase instability, challenges rooted in a narrow homogeneity range and uncontrolled Ag+ diffusion in the superionic phase. Here, we address these issues by exploiting liquid–solid interface reactions using CdSe complexes that remove surface excess Ag to yield stoichiometric Ag2Se and generate CdSe nanodomains that inhibit Ag+ diffusion and constrain grain growth. The resulting Ag2Se-CdSe nanocomposites exhibit a reproducible, stable figure of merit (zT) of 1.04 between 300 and 390 K. Beyond demonstrating high performance, we elucidate the interfacial chemical reactions that give rise to the observed microstructure and transport properties, providing a foundation for rationally engineering interfacial chemistry to tailor transport properties across diverse thermoelectric material systems.}, author = {Liu, Yu and Kleinhanns, Tobias and Horta, Sharona and Dutkiewicz, Ewelina and Lu, Shaoqing and Spadaro, Maria Chiara and Genç, Aziz and Chen, Lei and Lim, Khak Ho and Hong, Min and Arbiol, Jordi and Ibáñez, Maria}, issn = {1520-5126}, journal = {Journal of the American Chemical Society}, number = {35}, pages = {32199--32208}, publisher = {American Chemical Society}, title = {{Liquid-solid interface reactions drive enhanced thermoelectric performance in Ag2Se}}, doi = {10.1021/jacs.5c11435}, volume = {147}, year = {2025}, } @article{18707, abstract = {Lead Sulfide (PbS) has garnered attention as a promising thermoelectric (TE) material due to its natural abundance and cost-effectiveness. However, its practical application is hindered by inherently high lattice thermal conductivity and low electrical conductivity. In this study, we address these challenges by surface functionalization of PbS nanocrystals using Cu2S molecular complexes-based ligand displacement. The molecular complexes facilitate the incorporation of Cu into the PbS matrix and leads to the formation of nanoscale defects, dislocations, and strain fields while optimizing the charge carrier transport. The structural modulations enhance the phonon scattering and lead to a significant reduction in lattice thermal conductivity of 0.60 W m−1K−1 at 867 K in the PbS-Cu2S system. Simultaneously, the Cu incorporation improves electrical conductivity by increasing both carrier concentration and mobility with carefully optimized the content of Cu2S molecular complexes. These synergistic modifications yield a peak figure-of-merit (zT) of 1.05 at 867 K for the PbS-1.0 %Cu2S sample, representing an almost twofold enhancement in TE performance compared to pristine PbS. This work highlights the effectiveness of surface treatment in overcoming the intrinsic limitations of PbS-based materials and presents a promising strategy for the development of high-efficiency TE systems.}, author = {Shu, Haibo and Zhao, Mingjun and Lu, Shaoqing and Wan, Shanhong and Genç, Aziz and Huang, Lulu and Ibáñez, Maria and Lim, Khak Ho and Hong, Min and Liu, Yu}, issn = {1095-7103}, journal = {Journal of Colloid and Interface Science}, pages = {703--712}, publisher = {Elsevier}, title = {{Influence of surface engineering on the transport properties of lead sulfide nanomaterials}}, doi = {10.1016/j.jcis.2024.12.067}, volume = {683}, year = {2025}, } @article{17124, abstract = {In recent years, solution processes have gained considerable traction as a cost-effective and scalable method to produce high-performance thermoelectric materials. The process entails a series of critical steps: synthesis, purification, thermal treatments, and consolidation, each playing a pivotal role in determining performance, stability, and reproducibility. We have noticed a need for more comprehensive details for each of the described steps in most published works. Recognizing the significance of detailed synthetic protocols, we describe here the approach used to synthesize and characterize one of the highest-performing polycrystalline p-type SnSe. In particular, we report the synthesis of SnSe particles in water and the subsequent surface treatment with CdSe molecular complexes that yields CdSe-SnSe nanocomposites upon consolidation. Moreover, the surface treatment inhibits grain growth through Zenner pinning of secondary phase CdSe nanoparticles and enhances defect formation at different length scales. The enhanced complexity in the CdSe-SnSe nanocomposite microstructure with respect to SnSe promotes phonon scattering and thereby significantly reduces the thermal conductivity. Such surface engineering provides opportunities in solution processing for introducing and controlling defects, making it possible to optimize the transport properties and attain a high thermoelectric figure of merit.}, author = {Fiedler, Christine and Liu, Yu and Ibáñez, Maria}, issn = {1940-087X}, journal = {Journal of Visualized Experiments}, number = {207}, publisher = {MyJove Corporation}, title = {{Solution-processed, surface-engineered, polycrystalline CdSe-SnSe exhibiting low thermal conductivity}}, doi = {10.3791/66278}, volume = {2024}, year = {2024}, } @article{17052, abstract = {Production of thermoelectric materials from solution-processed particles involves the synthesis of particles, their purification and densification into pelletized material. Chemical changes that occur during each one of these steps render them performance determining. Particularly the purification steps, bypassed in conventional solid-state synthesis, are the cause for large discrepancies among similar solution-processed materials. In present work, the investigation focuses on a water-based surfactant free solution synthesis of SnSe, a highly relevant thermoelectric material. We show and rationalize that the number of leaching steps, purification solvent, annealing, and annealing atmosphere have significant influence on the Sn : Se ratio and impurity content in the powder. Such compositional changes that are undetectable by conventional characterization techniques lead to distinct consolidated materials with different types and concentration of defects. Additionally, the profound effect on their transport properties is demonstrated. We emphasize that understanding the chemistry and identifying key chemical species and their role throughout the process is paramount for optimizing material performance. Furthermore, we aim to demonstrate the necessity of comprehensive reporting of these steps as a standard practice to ensure material reproducibility.}, author = {Fiedler, Christine and Calcabrini, Mariano and Liu, Yu and Ibáñez, Maria}, issn = {1521-3773}, journal = {Angewandte Chemie International Edition}, number = {25}, publisher = {Wiley}, title = {{Unveiling crucial chemical processing parameters influencing the performance of solution-processed inorganic thermoelectric materials}}, doi = {10.1002/anie.202402628}, volume = {63}, year = {2024}, } @article{14734, abstract = {Developing cost-effective and high-performance thermoelectric (TE) materials to assemble efficient TE devices presents a multitude of challenges and opportunities. Cu3SbSe4 is a promising p-type TE material based on relatively earth abundant elements. However, the challenge lies in its poor electrical conductivity. Herein, an efficient and scalable solution-based approach is developed to synthesize high-quality Cu3SbSe4 nanocrystals doped with Pb at the Sb site. After ligand displacement and annealing treatments, the dried powders are consolidated into dense pellets, and their TE properties are investigated. Pb doping effectively increases the charge carrier concentration, resulting in a significant increase in electrical conductivity, while the Seebeck coefficients remain consistently high. The calculated band structure shows that Pb doping induces band convergence, thereby increasing the effective mass. Furthermore, the large ionic radius of Pb2+ results in the generation of additional point and plane defects and interphases, dramatically enhancing phonon scattering, which significantly decreases the lattice thermal conductivity at high temperatures. Overall, a maximum figure of merit (zTmax) ≈ 0.85 at 653 K is obtained in Cu3Sb0.97Pb0.03Se4. This represents a 1.6-fold increase compared to the undoped sample and exceeds most doped Cu3SbSe4-based materials produced by solid-state, demonstrating advantages of versatility and cost-effectiveness using a solution-based technology.}, author = {Wan, Shanhong and Xiao, Shanshan and Li, Mingquan and Wang, Xin and Lim, Khak Ho and Hong, Min and Ibáñez, Maria and Cabot, Andreu and Liu, Yu}, issn = {2366-9608}, journal = {Small Methods}, number = {8}, publisher = {Wiley}, title = {{Band engineering through Pb-doping of nanocrystal building blocks to enhance thermoelectric performance in Cu3SbSe4}}, doi = {10.1002/smtd.202301377}, volume = {8}, year = {2024}, } @article{15357, abstract = {There is a growing interest in cost-effective polycrystalline SnSe-based thermoelectric (TE) materials, which are able to replace the high performance but mechanically fragile and costly single-crystalline SnSe. In this study, we present a low-temperature solution-based approach to produce SnSe-PbSe nanocomposites with outstanding TE performance. Our method involves combining surfactant-free SnSe particles with oleate-capped PbSe nanocrystals in specific ratios, followed by thermal annealing and consolidation using spark plasma sintering. These nanocomposites are characterized by distinct compositional and structural properties that significantly impact their transport properties. In particular, the addition of oleate-capped PbSe nanocrystals results in: i) a reduction in the electrostatically adsorbed Na at the surface of the SnSe particles; ii) a reduction of Sn vacancies due to alloying with Pb; iii) an increase in grain boundary density; and iv) the formation of PbSnSe secondary phases. Notably, the SnSe-2.5 %PbSe nanocomposites demonstrate a 30 % decrease in thermal conductivity compared to that of the SnSe matrix. This reduction contributes to a maximum figure of merit (zT) of 1.75 at 788 K with a high average zT value of ca. 1.2 in the medium temperature range of 573–773 K. These values represent one of the highest reported in polycrystalline SnSe materials, showcasing the potential of our fabricated SnSe-PbSe nanocomposites for cost-effective TE applications.}, author = {Liu, Yu and Lee, Seungho and Fiedler, Christine and Spadaro, Maria Chiara and Chang, Cheng and Li, Mingquan and Hong, Min and Arbiol, Jordi and Ibáñez, Maria}, issn = {1385-8947}, journal = {Chemical Engineering Journal}, publisher = {Elsevier}, title = {{Enhancing thermoelectric performance of solutionpProcessed polycrystalline SnSe with PbSe nanocrystals}}, doi = {10.1016/j.cej.2024.151405}, volume = {490}, year = {2024}, } @article{12915, abstract = {Cu2–xS and Cu2–xSe have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, Cu2–xTe, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, zT, particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of Cu1.5–xTe–Cu2Se nanocomposites by consolidating surface-engineered Cu1.5Te nanocrystals. This surface engineering strategy allows for precise adjustment of Cu/Te ratios and results in a reversible phase transition at around 600 K in Cu1.5–xTe–Cu2Se nanocomposites, as systematically confirmed by in situ high-temperature X-ray diffraction combined with differential scanning calorimetry analysis. The phase transition leads to a conversion from metallic-like to semiconducting-like TE properties. Additionally, a layer of Cu2Se generated around Cu1.5–xTe nanoparticles effectively inhibits Cu1.5–xTe grain growth, minimizing thermal conductivity and decreasing hole concentration. These properties indicate that copper telluride based compounds have a promising thermoelectric potential, translated into a high dimensionless zT of 1.3 at 560 K.}, author = {Xing, Congcong and Zhang, Yu and Xiao, Ke and Han, Xu and Liu, Yu and Nan, Bingfei and Ramon, Maria Garcia and Lim, Khak Ho and Li, Junshan and Arbiol, Jordi and Poudel, Bed and Nozariasbmarz, Amin and Li, Wenjie and Ibáñez, Maria and Cabot, Andreu}, issn = {1936-086X}, journal = {ACS Nano}, number = {9}, pages = {8442--8452}, publisher = {American Chemical Society}, title = {{Thermoelectric performance of surface-engineered Cu1.5–xTe–Cu2Se nanocomposites}}, doi = {10.1021/acsnano.3c00495}, volume = {17}, year = {2023}, } @article{13235, abstract = {AgSbSe2 is a promising thermoelectric (TE) p-type material for applications in the middle-temperature range. AgSbSe2 is characterized by relatively low thermal conductivities and high Seebeck coefficients, but its main limitation is moderate electrical conductivity. Herein, we detail an efficient and scalable hot-injection synthesis route to produce AgSbSe2 nanocrystals (NCs). To increase the carrier concentration and improve the electrical conductivity, these NCs are doped with Sn2+ on Sb3+ sites. Upon processing, the Sn2+ chemical state is conserved using a reducing NaBH4 solution to displace the organic ligand and anneal the material under a forming gas flow. The TE properties of the dense materials obtained from the consolidation of the NCs using a hot pressing are then characterized. The presence of Sn2+ ions replacing Sb3+ significantly increases the charge carrier concentration and, consequently, the electrical conductivity. Opportunely, the measured Seebeck coefficient varied within a small range upon Sn doping. The excellent performance obtained when Sn2+ ions are prevented from oxidation is rationalized by modeling the system. Calculated band structures disclosed that Sn doping induces convergence of the AgSbSe2 valence bands, accounting for an enhanced electronic effective mass. The dramatically enhanced carrier transport leads to a maximized power factor for AgSb0.98Sn0.02Se2 of 0.63 mW m–1 K–2 at 640 K. Thermally, phonon scattering is significantly enhanced in the NC-based materials, yielding an ultralow thermal conductivity of 0.3 W mK–1 at 666 K. Overall, a record-high figure of merit (zT) is obtained at 666 K for AgSb0.98Sn0.02Se2 at zT = 1.37, well above the values obtained for undoped AgSbSe2, at zT = 0.58 and state-of-art Pb- and Te-free materials, which makes AgSb0.98Sn0.02Se2 an excellent p-type candidate for medium-temperature TE applications.}, author = {Liu, Yu and Li, Mingquan and Wan, Shanhong and Lim, Khak Ho and Zhang, Yu and Li, Mengyao and Li, Junshan and Ibáñez, Maria and Hong, Min and Cabot, Andreu}, issn = {1936-086X}, journal = {ACS Nano}, number = {12}, pages = {11923–11934}, publisher = {American Chemical Society}, title = {{Surface chemistry and band engineering in AgSbSe₂: Toward high thermoelectric performance}}, doi = {10.1021/acsnano.3c03541}, volume = {17}, year = {2023}, } @article{10566, abstract = {A versatile, scalable, room temperature and surfactant-free route for the synthesis of metal chalcogenide nanoparticles in aqueous solution is detailed here for the production of PbS and Cu-doped PbS nanoparticles. Subsequently, nanoparticles are annealed in a reducing atmosphere to remove surface oxide, and consolidated into dense polycrystalline materials by means of spark plasma sintering. By characterizing the transport properties of the sintered material, we observe the annealing step and the incorporation of Cu to play a key role in promoting the thermoelectric performance of PbS. The presence of Cu allows improving the electrical conductivity by increasing the charge carrier concentration and simultaneously maintaining a large charge carrier mobility, which overall translates into record power factors at ambient temperature, 2.3 mWm-1K−2. Simultaneously, the lattice thermal conductivity decreases with the introduction of Cu, leading to a record high ZT = 0.37 at room temperature and ZT = 1.22 at 773 K. Besides, a record average ZTave = 0.76 is demonstrated in the temperature range 320–773 K for n-type Pb0.955Cu0.045S.}, author = {Li, Mengyao and Liu, Yu and Zhang, Yu and Chang, Cheng and Zhang, Ting and Yang, Dawei and Xiao, Ke and Arbiol, Jordi and Ibáñez, Maria and Cabot, Andreu}, issn = {1385-8947}, journal = {Chemical Engineering Journal}, publisher = {Elsevier}, title = {{Room temperature aqueous-based synthesis of copper-doped lead sulfide nanoparticles for thermoelectric application}}, doi = {10.1016/j.cej.2021.133837}, volume = {433}, year = {2022}, } @article{10042, abstract = {SnSe has emerged as one of the most promising materials for thermoelectric energy conversion due to its extraordinary performance in its single-crystal form and its low-cost constituent elements. However, to achieve an economic impact, the polycrystalline counterpart needs to replicate the performance of the single crystal. Herein, we optimize the thermoelectric performance of polycrystalline SnSe produced by consolidating solution-processed and surface-engineered SnSe particles. In particular, the SnSe particles are coated with CdSe molecular complexes that crystallize during the sintering process, forming CdSe nanoparticles. The presence of CdSe nanoparticles inhibits SnSe grain growth during the consolidation step due to Zener pinning, yielding a material with a high density of grain boundaries. Moreover, the resulting SnSe–CdSe nanocomposites present a large number of defects at different length scales, which significantly reduce the thermal conductivity. The produced SnSe–CdSe nanocomposites exhibit thermoelectric figures of merit up to 2.2 at 786 K, which is among the highest reported for solution-processed SnSe.}, author = {Liu, Yu and Calcabrini, Mariano and Yu, Yuan and Lee, Seungho and Chang, Cheng and David, Jérémy and Ghosh, Tanmoy and Spadaro, Maria Chiara and Xie, Chenyang and Cojocaru-Mirédin, Oana and Arbiol, Jordi and Ibáñez, Maria}, issn = {1936-086X}, journal = {ACS Nano}, keywords = {tin selenide, nanocomposite, grain growth, Zener pinning, thermoelectricity, annealing, solution processing}, number = {1}, pages = {78--88}, publisher = {American Chemical Society}, title = {{Defect engineering in solution-processed polycrystalline SnSe leads to high thermoelectric performance}}, doi = {10.1021/acsnano.1c06720}, volume = {16}, year = {2022}, } @inproceedings{17062, author = {Ibáñez, Maria and Liu, Yu and Calcabrini, Mariano}, booktitle = {Proceedings of the nanoGe Spring Meeting 2022}, location = {Spain/Virtual}, publisher = {Fundació de la comunitat valenciana SCITO}, title = {{The importance of surface adsorbates in solution-processed thermoelectric materials}}, doi = {10.29363/nanoge.nsm.2022.159}, year = {2022}, } @article{11705, abstract = {The broad implementation of thermoelectricity requires high-performance and low-cost materials. One possibility is employing surfactant-free solution synthesis to produce nanopowders. We propose the strategy of functionalizing “naked” particles’ surface by inorganic molecules to control the nanostructure and, consequently, thermoelectric performance. In particular, we use bismuth thiolates to functionalize surfactant-free SnTe particles’ surfaces. Upon thermal processing, bismuth thiolates decomposition renders SnTe-Bi2S3 nanocomposites with synergistic functions: 1) carrier concentration optimization by Bi doping; 2) Seebeck coefficient enhancement and bipolar effect suppression by energy filtering; and 3) lattice thermal conductivity reduction by small grain domains, grain boundaries and nanostructuration. Overall, the SnTe-Bi2S3 nanocomposites exhibit peak z T up to 1.3 at 873 K and an average z T of ≈0.6 at 300–873 K, which is among the highest reported for solution-processed SnTe.}, author = {Chang, Cheng and Liu, Yu and Lee, Seungho and Spadaro, Maria and Koskela, Kristopher M. and Kleinhanns, Tobias and Costanzo, Tommaso and Arbiol, Jordi and Brutchey, Richard L. and Ibáñez, Maria}, issn = {1521-3773}, journal = {Angewandte Chemie International Edition}, number = {35}, publisher = {Wiley}, title = {{Surface functionalization of surfactant-free particles: A strategy to tailor the properties of nanocomposites for enhanced thermoelectric performance}}, doi = {10.1002/anie.202207002}, volume = {61}, year = {2022}, } @article{10858, abstract = {The cost-effective conversion of low-grade heat into electricity using thermoelectric devices requires developing alternative materials and material processing technologies able to reduce the currently high device manufacturing costs. In this direction, thermoelectric materials that do not rely on rare or toxic elements such as tellurium or lead need to be produced using high-throughput technologies not involving high temperatures and long processes. Bi2Se3 is an obvious possible Te-free alternative to Bi2Te3 for ambient temperature thermoelectric applications, but its performance is still low for practical applications, and additional efforts toward finding proper dopants are required. Here, we report a scalable method to produce Bi2Se3 nanosheets at low synthesis temperatures. We studied the influence of different dopants on the thermoelectric properties of this material. Among the elements tested, we demonstrated that Sn doping resulted in the best performance. Sn incorporation resulted in a significant improvement to the Bi2Se3 Seebeck coefficient and a reduction in the thermal conductivity in the direction of the hot-press axis, resulting in an overall 60% improvement in the thermoelectric figure of merit of Bi2Se3.}, author = {Li, Mengyao and Zhang, Yu and Zhang, Ting and Zuo, Yong and Xiao, Ke and Arbiol, Jordi and Llorca, Jordi and Liu, Yu and Cabot, Andreu}, issn = {2079-4991}, journal = {Nanomaterials}, keywords = {General Materials Science, General Chemical Engineering}, number = {7}, publisher = {MDPI}, title = {{Enhanced thermoelectric performance of n-type Bi2Se3 nanosheets through Sn doping}}, doi = {10.3390/nano11071827}, volume = {11}, year = {2021}, } @article{9118, abstract = {Cesium lead halides have intrinsically unstable crystal lattices and easily transform within perovskite and nonperovskite structures. In this work, we explore the conversion of the perovskite CsPbBr3 into Cs4PbBr6 in the presence of PbS at 450 °C to produce doped nanocrystal-based composites with embedded Cs4PbBr6 nanoprecipitates. We show that PbBr2 is extracted from CsPbBr3 and diffuses into the PbS lattice with a consequent increase in the concentration of free charge carriers. This new doping strategy enables the adjustment of the density of charge carriers between 1019 and 1020 cm–3, and it may serve as a general strategy for doping other nanocrystal-based semiconductors.}, author = {Calcabrini, Mariano and Genc, Aziz and Liu, Yu and Kleinhanns, Tobias and Lee, Seungho and Dirin, Dmitry N. and Akkerman, Quinten A. and Kovalenko, Maksym V. and Arbiol, Jordi and Ibáñez, Maria}, issn = {2380-8195}, journal = {ACS Energy Letters}, number = {2}, pages = {581--587}, publisher = {American Chemical Society}, title = {{Exploiting the lability of metal halide perovskites for doping semiconductor nanocomposites}}, doi = {10.1021/acsenergylett.0c02448}, volume = {6}, year = {2021}, } @article{9206, abstract = {The precise engineering of thermoelectric materials using nanocrystals as their building blocks has proven to be an excellent strategy to increase energy conversion efficiency. Here we present a synthetic route to produce Sb-doped PbS colloidal nanoparticles. These nanoparticles are then consolidated into nanocrystalline PbS:Sb using spark plasma sintering. We demonstrate that the introduction of Sb significantly influences the size, geometry, crystal lattice and especially the carrier concentration of PbS. The increase of charge carrier concentration achieved with the introduction of Sb translates into an increase of the electrical and thermal conductivities and a decrease of the Seebeck coefficient. Overall, PbS:Sb nanomaterial were characterized by two-fold higher thermoelectric figures of merit than undoped PbS. }, author = {Cadavid, Doris and Wei, Kaya and Liu, Yu and Zhang, Yu and Li, Mengyao and Genç, Aziz and Berestok, Taisiia and Ibáñez, Maria and Shavel, Alexey and Nolas, George S. and Cabot, Andreu}, issn = {1996-1944}, journal = {Materials}, number = {4}, publisher = {MDPI}, title = {{Synthesis, bottom up assembly and thermoelectric properties of Sb-doped PbS nanocrystal building blocks}}, doi = {10.3390/ma14040853}, volume = {14}, year = {2021}, }