Search

Thermoelectric (TE) technologies offer promising means to enhance fossil energy efficiencies by generating electricity from waste heat from industrial or automobile exhaust gases. For these applications, thermoelectric modules should be designed from the perspective of system integration for efficient heat transfer, system simplification, and low processing cost. However, typical thermoelectric modules manufactured by traditional processes do not fulfil such requirements, especially for exhaust pipes. Hence, a 3D‐printing method for PbTe thermoelectric materials is reported to design high‐performance power‐generating TE tubes. The electronic doping‐induced surface charges in PbTe particles are shown to significantly improve the viscoelasticities of inks without additives, thereby enabling precise shape and dimension engineering of 3D bulk PbTe with figures of merit of 1.4 for p‐type and 1.2 for n‐type materials. The performance of the power‐generating TE tube fabricated from 3D‐printed PbTe tubes is demonstrated experimentally and computationally as an effective strategy to design system‐adaptive high‐performance thermoelectric generators. [ABSTRACT FROM AUTHOR]

3D printing, doping, PbTe, power generators, thermoelectric materials Thermoelectric Generators: Doping-Induced Viscoelasticity in PbTe Thermoelectric Inks for 3D Printing of Power-Generating Tubes (Adv. Keywords: 3D printing; doping; PbTe; power generators; thermoelectric materials EN 3D printing doping PbTe power generators thermoelectric materials 1 1 1 06/05/21 20210527 NES 210527 In article number 2100190, Sung Youb Kim, Han Gi Chae, Jae Sung Son and co-workers design additive-free viscoelastic inks tailored by electronic doping-induced surface charges of particles, which enable the extrusion-based 3D printing of high-performance PbTe thermoelectric materials. [Extracted from the article]

Molecular and nanoscale amphiphiles have been extensively studied as building blocks for organizing macroscopic matter through specific and local interactions. Among various amphiphiles, inorganic Janus nanoparticles have attracted a lot of attention owing to their ability to impart multifunctionalities, although the programmability to achieve complicated self-assembly remains a challenge. Here, we synthesized matchstick-shaped Janus nano-surfactants that mimic organic surfactant molecules and studied their programmable self-assembly. High amphiphilicity was achieved through the hard-soft acid-base-based ligand-exchange reaction with strong selectivity on the surface of nano-matchsticks consisting of Ag 2 S heads and CdS stems. The obtained nano-surfactants spontaneously assembled into diverse ordered structures such as lamellar, curved, wrinkled, cylindrical, and micellar structures depending on the vertical asymmetry and the interfacial tension controlled by their geometry and surface ligands. The correlation between the phase selectivity of suprastructures and the characteristics of nano-surfactants is discussed. This study realized the molecular amphiphile-like programmability of inorganic Janus nanostructures in self-assembly with the precise control on the surface chemistry., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Electronically doped nanoparticles formed by incorporation of impurities have been of great interest because of their controllable electrical properties. However, the development of a strategy for n-type or p-type doping on sub-10 nm-sized nanoparticles under the quantum confinement regime is very challenging using conventional processes, owing to the difficulty in synthesis. Herein, we report the colloidal chemical synthesis of sub-10 nm-sized tellurium (Te)-doped Bismuth (Bi) nanoparticles with precisely controlled Te content from 0 to 5% and systematically investigate their low-temperature charge transport and thermoelectric properties. Microstructural characterization of nanoparticles demonstrates that Te ions are successfully incorporated into Bi nanoparticles rather than remaining on the nanoparticle surfaces. Low-temperature Hall measurement results of the hot-pressed Te-doped Bi-nanostructured materials, with grain sizes ranging from 30 to 60 nm, show that the charge transport properties are governed by the doping content and the related impurity and nanoscale grain boundary scatterings. Furthermore, the low-temperature thermoelectric properties reveal that the electrical conductivity and Seebeck coefficient expectedly change with the Te content, whereas the thermal conductivity is significantly reduced by Te doping because of phonon scattering at the sites arising from impurities and nanoscale grain boundaries. Accordingly, the 1% Te-doped Bi sample exhibits a higher figure-of-merit ZT by ∼10% than that of the undoped sample. The synthetic strategy demonstrated in this study offers the possibility of electronic doping of various quantum-confined nanoparticles for diverse applications.

We report a strategy toward the synthesis of colloidal nanocrystals capped with inorganic molybdenum and tungsten sulfide ligands. MoS4(2-) and WS4(2-) thiometalates were utilized to replace organic ligands capping a wide range of nanocrystals such as metals, semiconductors, and well-conserved primary properties of nanocrystals in polar media. Especially, MoS4(2-)- and WS4(2-)-capped CdSe nanocryatals showed the dramatic enhancement of photoluminescence properties by the photo-oxidation treatment, which originated from the preferential formation of MoSxOy layers on the CdSe surface. The highest quantum yield reached up to 51%. Furthermore, we studied the charge-transport properties of MoS4(2-)-capped PbS nanocryatals by the fabrication of a field-effect transistor and photodetectors. Finally, MoS4(2-)- and WS4(2-)-capped nanocrystals were used for the production of two-dimensional MoS2 and WS2 thin layers on nanostructures by heat treatment. Such versatility of these thiometalate ligands offers an additional degree of control over the functionality of nanocrystals for optoelectronic and catalytic applications.