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In this work, flexible Cu2−xS films on nylon membranes are prepared by combining a simple hydrothermal synthesis and vacuum filtration followed by hot pressing. The films consist of Cu2S and Cu1.96S two phases with grain sizes from nano to submicron. Doping Se on the S site not only increases the Cu1.96S content in the Cu2−xS to increase carrier concentration but also modifies electronic structure, thereby greatly improves the electrical properties of the Cu2−xS. Specifically, an optimal composite film with a nominal composition of Cu2−xS0.98Se0.02 exhibits a high power factor of ~150.1 μW m−1 K−2 at 300 K, which increases by ~138% compared to that of the pristine Cu2−xS film. Meanwhile, the composite film shows outstanding flexibility (~97.2% of the original electrical conductivity is maintained after 1500 bending cycles with a bending radius of 4 mm). A four-leg flexible thermoelectric (TE) generator assembled with the optimal film generates a maximum power of 329.6 nW (corresponding power density of 1.70 W m−2) at a temperature difference of 31.1 K. This work provides a simple route to the preparation of high TE performance Cu2−xS-based films. [ABSTRACT FROM AUTHOR]

Copper-sulfide-based materials have attracted noteworthy attention as thermoelectric materials due to rich elemental reserves, non-toxicity, low thermal conductivity, and adjustable electrical properties. However, research on the flexible thermoelectrics of copper sulfide has not yet been reported. In this work, we developed a facile method to prepare flexible Mn-doped Cu2−xS films on nylon membranes. First, nano to submicron powders with nominal compositions of Cu2−xMnyS (y = 0, 0.01, 0.03, 0.05, 0.07) were synthesized by a hydrothermal method. Then, the powders were vacuum-filtrated on nylon membranes and finally hot-pressed. Phase composition and microstructure analysis revealed that the films contained both Cu2S and Cu1.96S, and the size of the grains was ~20–300 nm. By Mn doping, there was an increase in carrier concentration and mobility, and ultimately, the electrical properties of Cu2−xS were improved. Eventually, the Cu2−xMn0.05S film showed a maximum power factor of 113.3 μW m−1 K−2 and good flexibility at room temperature. Moreover, an assembled four-leg flexible thermoelectric generator produced a maximum power of 249.48 nW (corresponding power density ~1.23 W m−2) at a temperature difference of 30.1 K, and had good potential for powering low-power-consumption wearable electronics. [ABSTRACT FROM AUTHOR]

Cu 0.05 Bi 2 Se x Te 3−x (x=0.2, 0.3, 0.4) bulk samples were prepared by hot pressing corresponding nanopowders synthesized by a gas-induced reduction method. Se doping significantly increases the carrier concentrations and hence the electrical conductivities of the samples. Based on this, a Cu 0.05 Bi 2 Se 0.3 Te 2.7 sample with a higher power factor was chosen as a pristine sample; some of the Cu 0.05 Bi 2 Se 0.3 Te 2.7 nanopowders were mixed with various amounts of Bi nanoparticles (NPs) and then hot pressed into bulk samples. The addition of Bi NPs promotes the sintering of samples. When the content of Bi NPs added is low (≤1 wt%), the electrical conductivity is higher than the pristine sample, and all the Bi NPs added samples have higher Seebeck coefficient than the pristine sample, hence, the power factor has been improved. A maximum power factor, 30.6 µWcm −1 K −2 , has been obtained for the 2 wt% Bi NPs added sample. [ABSTRACT FROM AUTHOR]

Highlights: [•] The electronic structure and some transport properties of Mn3Cu4Bi4 was studied used by DFT. [•] The result shows that the Seebeck coefficient of Mn3Cu4Bi4 is isotropic and reaches 30.9μV/K. [•] It is the first time to report the Seebeck coefficient of Mn3Cu4Bi4. [ABSTRACT FROM AUTHOR]

Abstract: SnSe1−x Te x (x=0, 0.0625) bulk materials were fabricated by melting Sn, Se and Te powders and then hot pressing them at various temperatures. The phase compositions of the materials were determined by X-ray diffraction (XRD) and the crystal lattice parameters were refined by the Rietveld method performed with DBWS. XRD analysis revealed that the grains in the materials preferentially grew along the (l00) directions. The structural behavior of SnSe1−x Te x (x=0, 0.0625) was calculated using CASTEP package provided by Materials Studio. We found that the band gap of SnSe reduced from 0.643 to 0.608eV after Te doping. The calculated results were in good agreement with experimental results. The electrical conductivity and the Seebeck coefficient of the as-prepared materials were measured from room temperature to 673K. The maximum power factor of SnSe is ∼0.7μWcm−1K−2 at 673K. [Copyright &y& Elsevier]

Conductive poly( p -phenylenediamine) (PpPD) nanopowders doped with different-concentration hydrochloric acid (HCl) were synthesized by a typical chemical oxidative polymerization method. The PpPD powders were characterized by the Fourier transform infrared spectroscopy, UV–vis spectroscopy, 1 H nuclear magnetic resonance spectroscopy and transmission electron microscope. The results showed that the morphology of the products changed from mainly spherical nanoparticles of the pure PpPD to rod-like nanoparticles of HCl doped PpPD. The pure PpPD showed n-type conduction whereas the HCl doped PpPD exhibited p-type conduction. The PpPD doped by 1 M HCl showed a maximum power factor of about 0.56 μW m −1 K −2 at room temperature. The mechanism of the change of the conduction type has also been discussed. [ABSTRACT FROM AUTHOR]