[en] The wet-chemical approach is of great significance for the synthesis of two-dimensional (2D) bismuth telluride nanoplatelets as a potential thermoelectric (TE) material. Herein, we proposed a simple and effective solution method with the assistance of aniline for the fabrication of bismuth telluride nanoplatelets at a low temperature of 100 °C. The choice of aniline with its dual function avoided the simultaneous use of a capping regent and a toxic reductant. The as-synthesized nanoplatelets have a large size of more than 900 × 500 nm² and a small thickness of 15.4 nm. The growth of bismuth telluride nanoplatelets are related to the Bi/Te ratio of precursors indicating that a larger content of the Bi precursor is more conducive to the formation of 2D nanoplatelets. The bismuth telluride nanoplatelets pressed into a pellet show a smaller electrical resistivity (∼6.5 × 10⁻³ Ω · m) and a larger Seebeck coefficient (−135 μ V K⁻¹), as well as a lower thermal conductivity (0.27 W m⁻¹ K⁻¹) than those of nanoparticles. The next goal is to further reduce the electrical resistivity and optimize the TE performance by disposing of the residual reactant of aniline adsorbed on the surface of the nanoplatelets. (paper)

[en] MoS₂ has been predicted to be an excellent thermoelectric material due to its large intrinsic band gap and high carrier mobility. In this work, we exfoliated bulk MoS₂ by the assistance of lithium intercalation and fabricated the restacked MoS₂ thin-film using a simple filtration technique. These MoS₂ thin-films with different thickness showed different thermoelectric performance. It was found that with the increase of thickness, carrier concentration, electrical conductivity and Seebeck coefficient all showed an increasing trend. In particular, the maximum Seebeck coefficient was able to reach 93.5 μ V K⁻¹. This high thermopower indicates that MoS₂ will have ideal thermoelectric performance in the future through optimizing its structure. The highest figure of merit ( ZT = 0.01) is calculated in this experiment. (paper)

[en] Flexible wearable power-conversion devices have attracted more and more attentions for the researches, with the development of science and technology. As an alternative, we show a simple solution processable method for enhancing the thermoelectric (TE) properties of flexible single-wall carbon nanotubes based (SWCNTs-based) composites. Tellurium (Te) nanoparticles distributed on SWCNTs affecting the intrinsic carrier concentration and energy barrier of the composites, which resulting in the enhanced Seebeck coefficient and power factor. The optimized flexible TE composite films show a high power factor of 36.4 μW m⁻¹ K⁻², which is more than one order of magnitude higher than the previous optimized SWCNTs-Te composites with SWCNTs and Te nanowires. The optimized composite film also displayed high flexibility, the electrical conductivity only decreases by about 17% at 1000 bends. This work proposes a simple approach to improve Seebeck coefficient and power factor for flexible SWCNTs-based composite films. - Highlights: • SWCNT-Te composite was fabricated with simple solution processable method. • The introduction of Te atom affected the intrinsic carrier concentration and energy barrier. • SWCNT-Te films displayed an enhanced power factor and great flexibility.

[en] Highlights: • Seebeck coefficient of the as-synthesized Te NWs was as high as 551 μV K⁻¹. • The freestanding Te NWs nanofilms show good flexibility with PVDF. • The ultra-fine Te NWs have a narrow diameter range from 10 to 35 nm. - Abstract: Low-dimensional tellurium-based nanowires (NWs) have gained much attention as ideal thermoelectric materials. The preparation of high quality NWs remains a challenge in the field of nanotechnology. Owing to the superior performance, tellurium (Te) NWs are attractive materials for many applications. In this work, the Te NWs were synthesized by a hydrothermal route. We acquired the ultra-fine Te NWs through optimization, and the diameter is 10–35 nm. The optimized Te nanofilm was freestanding and the Te/polyvinylidene fluoride film can be rolled up by a pencil which showed the flexibility of the membrane. The as-prepared Te NWs films have been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Although the ultra-fine Te NWs film shows the acceptable electrical conductivity, its Seebeck coefficient is as high as 551 μV K⁻¹ and the thermal conductivity is as low as 0.16 W m⁻¹ K⁻¹. To achieve a higher thermoelectric performance, the effort will be devoted into the improvement of electrical conductivity in next work.

[en] Understanding the interplay between magnetic and optoelectronic properties and developing spin-optoelectronic devices are promising research strategies to further study 2D materials and advance their applications. Here, the broadband photoresponse in the newly synthesized magnetic Fe${}_{0.75}$Ta${}_{0.5}$S${}_2$ single crystals is reported. Because the uncompensated magnetic moment of the spin glass state is pinned by the moment of the antiferromagnetic state, a large exchange bias field of ≈1.98 T is found at 2 K when cooled down at a field of 7 T. The as-prepared samples show a large negative magnetoresistance (nMR). The field dependence of nMRs displays a similar trend up to 50 K, which is likely to originate from the significant dependence of the localization length on magnetic field. In addition, a photodetector prepared using Fe${}_{0.75}$Ta${}_{0.5}$S${}_2$ flakes exhibits a fast response time (121.7 ms), good stability, high responsivity of 26.1 A W${}^{-<!--\; ???\; -->1}$, and broadband photodetection, showing application potentials in spin-optoelectronics. (© 2022 Wiley‐VCH GmbH)

[en] Highlights: • A flexible PEDOT:PSS/SiC-NWs hybrid thermoelectric generator have been fabricated. • The introduction of SiC-NWs improves the thermoelectric performance of PEDOT:PSS. • H₂SO₄ post-treatment shows positive effect on thermoelectric performance of hybrid thin film. • A large open-circuit voltage of 21.9 mV has been achieved for the flexible generator. A nanoscale organic/inorganic hybrid thin film has been fabricated with the conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and SiC nanowires (SiC-NWs) defined as PEDOT:PSS/SiC-NWs by a facile dilution-filtration method and the thermoelectric (TE) performance has been investigated systematically. It has been demonstrated that a low content of SiC-NWs (< 10 wt%) can effectively enhance the Seebeck coefficient of PEDOT:PSS films by 36.6% (20.9 μV K⁻¹) with maintaining a high electrical conductivity of 1550 S cm⁻¹. A high power factor of 67.7 μW m⁻¹ K⁻² for the PEDOT:PSS/SiC-NWs with 3.0 wt% high purity SiC-NWs (p-SiC-NWs) was obtained and further enhanced to 128.3 μW m⁻¹ K⁻² after H₂SO₄ post-treatment, which is two times higher than that of pre-treatment and four times higher than that of pure PEDOT:PSS (31.8 μW m⁻¹ K⁻²). Based on the thermal conductivity measured to be 0.23 W m⁻¹ K⁻¹, the maximum ZT value was achieved as high as 0.17. Finally, a flexible TE generator has been designed and fabricated by parallel connected ten legs of the as-prepared H₂SO₄ post-treated PEDOT:PSS/p-SiC-NWs₃ hybrid thin films. The maximum open-circuit voltage of 21.9 mV and output power of 180 nW at ΔT = 100 K were obtained, which show great potential for the flexible TE generator development.