High-performance flexible thermoelectric modules based on high crystal quality printed TiS2/hexylamine.

Printed electronics implies the use of low-cost, scalable, printing technologies to fabricate electronic devices and circuits on flexible substrates, such as paper or plastics. The development of this new electronic is currently expanding because of the emergence of the internet-of-everything. Although lot of attention has been paid to functional inks based on organic semiconductors, another class of inks is based on nanoparticles obtained from exfoliated 2D materials, such as graphene and metal sulfides. The ultimate scientific and technological challenge is to find a strategy where the exfoliated nanoparticle flakes in the inks can, after solvent evaporation, form a solid which displays performances equal to the single crystal of the 2D material. In this context, a printed layer, formed from an ink composed of nano-flakes of TiS2 intercalated with hexylamine, which displays thermoelectric properties superior to organic intercalated TiS2 single crystals, is demonstrated for the first time. The choice of the fraction of exfoliated nano-flakes appears to be a key to the forming of a new self-organized layered material by solvent evaporation. The printed layer is an efficient n-type thermoelectric material which complements the p-type printable organic semiconductors The thermoelectric power factor of the printed TiS2/hexylamine thin films reach record values of 1460 µW m-1 K-2 at 430 K, this is considerably higher than the high value of 900 µW m-1 K-2 at 300 K reported for a single crystal. A printed thermoelectric generator based on eight legs of TiS2 confirms the high-power factor values by generating a power density of 16.0 W m-2 at ΔT = 40 K.

Cognitive profile of school-age children and teenagers with hypohidrotic ectodermal dysplasia (HED).

Anhidrotic/hypohidrotic ectodermal dysplasia (HED) is the most common of the ectodermal dysplasias characterized by a triad of absent or reduced sweat, hypodontia and misshapen teeth, and missing or sparse hair. As the central nervous system is primarily ectodermal in origin, it has long been a concern that HED may be associated with developmental delay and/or intellectual disabilities. While published reviews report abnormalities in mental or motor development in 15-25% of HED-affected patients, there is no report in the literature including a systematic assessment of intellectual abilities in a cohort of patients with this rare disorder. During yearly health care updates, many of our clinic families report attention difficulties in young HED patients without evidence of a significant impact on school performance. In an exploratory study to identify and quantify intellectual abnormalities that may be associated with HED, we performed a psychological examination of 23 HED patients by means of the Wechsler Intelligence Scales, WPPSI-III, and WISC-IV. The interpretation of the tests shows no significant impairment in the achievements of the sample group compared with normative values (full scale scores, and index scale scores of the WISC-IV). At an individual level, the HED-affected patients were characterised by higher scores on the Verbal Comprehension Index, on Perceptual Reasoning and Working Memory Indices, and lower scores on the Processing Speed Index. As all of the Indices were within normal limits for the study population, in the absence of major mental/motor disabilities these findings support the mainstream education of HED-affected children.

Integrated computational materials discovery of silver doped tin sulfide as a thermoelectric material.

Accelerating the discovery of new materials is crucial for realizing the vision of need-driven materials development. In the present study we employ an integrated computational and experimental approach to search for new thermoelectric materials. High-throughput first principles calculations of thermoelectric transport coefficients are used to screen sulfide compounds conforming to the boundary conditions of abundant and innocuous components. A further computational screening step of substitutional defects is introduced, whereby SnS doped with monovalent cations is identified as having favorable transport properties. By silver doping of SnS under S-rich conditions an electric conductivity more than an order of magnitude higher than reported previously is realized. The obtained thermoelectric power-factor at room temperature is comparable to the state of the art for thermoelectric materials based on earth abundant, non-toxic elements. The high-throughput screening of extrinsic defects solves a long standing bottleneck in search of new thermoelectric materials. We show how the intrinsic carrier concentration in the low-temperature phase of SnSe is two orders of magnitude higher than in SnS. We furthermore find that the carrier concentration in SnSe can still be further optimized by silver doping.

Strong Reduction of Thermal Conductivity and Enhanced Thermoelectric Properties in CoSbS1-xSex Paracostibite.

In order to reduce the thermal conductivity of CoSbS, a newly developed thermoelectric semiconductor, we have aimed at intentionally induce atomic disorder in its structure. This endeavor was guided by Density Functional Theory(DFT) calculations which indicated that substituting sulfur with selenium might be easily achievable experimentally because of the low formation energy of this point defect. Thereby, CoSbS1-xSex compounds having 0 ≤ x ≤ 1 have been synthesized by solid state reaction. Besides the expected semiconducting paracostibite phase, we have observed the appearance of a semimetallic costibite phase, never reported experimentally before. This cross-fertilized theoretical and experimental approach allowed us to reduce by 50% the thermal conductivity of paracostibite and therefore reach a maximum zT of 0.62 at 730 K. This makes this entirely new CoSbS1-xSex alloy very attractive for further optimizations and potential usage in thermoelectric applications.