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This study introduces the synthesis of a hybrid thermoelectric material with enhanced conductivity and a high Seebeck coefficient, leveraging the properties of Te nanowires (NWs) and the conductive polymer PEDOT:PSS. Te NWs were synthesized using the galvanic displacement reaction. To further enhance conductivity, Ag-Te NWs were synthesized under optimized conditions via the Ag topotactic reaction, achieving desired results within 7 min using ethylene glycol and AgNO3. This hybrid material exhibited an electrical conductivity of 463 S/cm, a Seebeck coefficient of 69.5 μV/K at 300 K, and a power factor of 260 μW/mK2. These metrics surpassed those of conventional Te/PEDOT:PSS hybrids by a factor of 3.6, highlighting the superior performance of our approach. This study represents a significant advancement in thermoelectric materials, improving both conductivity and efficiency. [ABSTRACT FROM AUTHOR]

This study introduces the synthesis of a hybrid thermoelectric material with enhanced conductivity and a high Seebeck coefficient, leveraging the properties of Te nanowires (NWs) and the conductive polymer PEDOT:PSS. Te NWs were synthesized using the galvanic displacement reaction. To further enhance conductivity, Ag-Te NWs were synthesized under optimized conditions via the Ag topotactic reaction, achieving desired results within 7 min using ethylene glycol and AgNO3. This hybrid material exhibited an electrical conductivity of 463 S/cm, a Seebeck coefficient of 69.5 µV/K at 300 K, and a power factor of 260 µW/Mk². These metrics surpassed those of conventional Te/PEDOT:PSS hybrids by a factor of 3.6, highlighting the superior performance of our approach. This study represents a significant advancement in thermoelectric materials, improving both conductivity and efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] Organic thermoelectrics (TEs) based on carbon nanotubes (CNTs) have attracted much attention with their inherent advantages, such as, earth-abundant elements, broad electronic tunability, and excellent mechanical compliance. However, the inferior TE performance and doping stability of n-type CNTs to those of p-type CNTs have been bottlenecks to establish CNT-based next-generation TEs. Herein, we report a hybrid n-doping method that improves the n-type TE performance and long-term air-stability of water-processable single-walled CNT (SWCNT) and carboxymethyl cellulose (CMC) composite. The hybrid n-doping process with polyethyleneimine (PEI) n-dopant contains primary addition and secondary immersion doping, which causes a simultaneous increase in electrical conductivity and Seebeck coefficient through efficient n-doping and surface energy filtering effect, respectively. Furthermore, the hybrid-doped films exhibit superior long-term stability by inhibiting the oxidation of SWCNT/CMC at nanoscale, which allows to ensure the initial power factor even after storing in ambient for a month. Finally, we successfully demonstrated hybrid-doped SWCNT/CMC-based TEGs with long-term stable output characteristics. This work can offer insights to develop efficient and air-stable n-type organic TE materials and devices. [ABSTRACT FROM AUTHOR]

The thermoelectric (TE) properties of Nb-doped (CuI)0.003Bi2− x Nb x Te2.7Se0.3 compounds (x = 0, 0.005, 0.01 and 0.03), were investigated at temperatures ranging from 300 to 600 K. Among the compounds studied, the lightly substituted (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 compound exhibited the best TE performance due to the improvement in its electrical conductivity and its relatively unchanged Seebeck coefficient due to Nb doping. Its figure of merit, ZT, was greater than the undoped (CuI)0.003Bi2Te2.7Se0.3 compound for the temperature range investigated. In particular, the ZT of (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 reached a value of 0.65 at 448 K in this study. [ABSTRACT FROM AUTHOR]

The thermoelectric (TE) properties of Nb-doped (CuI)0.003Bi2− x Nb x Te2.7Se0.3 compounds (x = 0, 0.005, 0.01 and 0.03), were investigated at temperatures ranging from 300 to 600 K. Among the compounds studied, the lightly substituted (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 compound exhibited the best TE performance due to the improvement in its electrical conductivity and its relatively unchanged Seebeck coefficient due to Nb doping. Its figure of merit, ZT, was greater than the undoped (CuI)0.003Bi2Te2.7Se0.3 compound for the temperature range investigated. In particular, the ZT of (CuI)0.003Bi1.995Nb0.005Te2.7Se0.3 reached a value of 0.65 at 448 K in this study. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid thermoelectric (TE) materials have attracted tremendous interest for harvesting waste heat energy. Due to their mechanical flexibility, inorganic‐organic hybrid TE materials are considered to be promising candidates for flexible energy harvesting devices. In this work, enhanced TE properties of Tellurium (Te) nanowires (NWs)‐ poly (3‐hexylthiophene‐2, 5‐diyl) (P3HT) hybrid materials are reported by improving the charge transport at interfacial layer mediated via controlled oxidation. A power factor of ≈9.8 µW (mK2)−1 is obtained at room temperature for oxidized P3HT‐TeNWs hybrid materials, which increases to ≈64.8 µW (mK2)−1 upon control of TeNWs oxidation. This value is sevenfold higher compared to P3HT‐TeNWs‐based hybrid materials reported in the literature. MD simulation reveals that oxidation‐free TeNWs demonstrate better templating for P3HT polymer compared to oxidized TeNWs. The Kang–Snyder model is used to study the charge transport in these hybrid materials. A large σE0 value is obtained which is related to better templating of P3HT on oxygen‐free TeNWs. This work provides evidence that oxidation control of TeNWs is critical for better interface‐driven charge transport, which enhances the thermoelectric properties of TeNWs‐P3HT hybrid materials. This work provides a new avenue to improve the thermoelectric properties of a new class of hybrid thermoelectric materials. [ABSTRACT FROM AUTHOR]

The thermal transport and thermoelectric properties of CsCdX3 (X = Cl, Br) were investigated using first-principles calculations and machine learning interatomic potentials. The lattice thermal conductivity was obtained including the effect of temperature on the phonon dispersion spectrum and the contribution of the diffuson-like phonons, based on the self-consistent phonon (SCP) and two-channel phonon transport theories. We found that diffuson-like phonons contribute significantly to the lattice thermal transport. The ultralow lattice thermal conductivities of CsCdCl3 and CsCdBr3 at 300 K are 0.95 W/mK and 0.57 W/mK, respectively. The large Seebeck coefficient of CsCdCl3 and CsCdBr3 is about 800 μV/K and 700 μV/K at 900 K, due to the multi-valley energy band structure. The calculated maximum ZT of p-type CsCdBr3 is 1.16 at 900 K, larger than most of the reported halide perovskite materials. We suggest that CsCdBr3 is a promising candidate for thermoelectric halide perovskite materials. [ABSTRACT FROM AUTHOR]

In this work, we examine the formation of iron-based magnetic domains on two-dimensional (2D) single-crystal bismuth telluride plates. Using solvothermal chemical methods, 2D bismuth telluride (Bi2Te3) single crystalline nanoplates were reacted with iron salts (FeCl2) to achieve electrical doping. The use of a reducing agent [L(+)-ascorbic acid] along with FeCl2 resulted in homogeneous dispersion of iron across the crystal, whereas non-reduced iron doping achieved edge growth of iron/iron oxide nanoparticles. High-resolution analytical electron microscopy was used to examine the iron nanoparticle accumulation and morphology at nanoplate edges for non-reduced materials and iron dispersions within the crystals in the case of reduction. Our analysis revealed little variation in the atomic uptake of iron in any form over a range of solution-dopant concentrations. However, structural analysis and transport measurements clearly indicate the tendency of the dopant nanoparticles to oxidize quickly. The Seebeck coefficient and power factor also express modifications with exposure to oxidation, providing an indirect probe of the dopant modification to the host Bi2Te3's electronic properties. Importantly, however, magnetic force microscopy images show a distinct difference in the formation of magnetic phases with and without the use of reducing agents during iron doping. This suggests that oxidation post-doping does not form magnetic phases, whereas oxidation during the doping process is suitable for obtaining magnetically doped Bi2Te3 nanocrystals. [ABSTRACT FROM AUTHOR]

Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics (PFmax=$PF_{\text{max}} =$ 21.5 µW cm−1 K−2 and zTmax=$zT_{\text{max}} =$ 0.5 at 1100 K in Zn0.96Al0.04O${\rm Zn}_{0.96} {\rm Al}_{0.04}{\rm O}$) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics. [ABSTRACT FROM AUTHOR]

Fiber‐based flexible thermoelectric (TE) generators are highly desirable due to their capability to convert thermal energy into electricity and their potential applications in wearable electronics. High‐performance poly(3,4‐ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Tellurium (Te) composite TE fibers have been successfully developed via a continuous wet‐spinning approach followed by sulphuric acid treatment. With a simple pre‐modification to Te nanowires, the inorganic Te fillers form uniform distribution in PEDOT:PSS. At the optimal condition, the composite fibers exhibit a power factor of 233.5 µW m−1 K−2 and mechanical strength of 205 MPa, which are among the highest values reported so far for the PEDOT:PSS‐based TE fibers. From the viewpoint of TE property enhancement mechanism, understanding the morphology and carrier transport behavior in the 1D organic/inorganic composite fibers remains still challenging. On basis of a series of PEDOT:PSS/Te composite fibers with varying Te fractions, orientations of both the inorganic and organic constituents are quantitatively evaluated. Their electrical conductivities and Seebeck coefficients are also analyzed with modified series‐parallel models and energy filtering theory. This work may not only provide a universal approach to produce high‐performance organic/inorganic composite TE fibers for various wearable applications, but also help to understand the morphology and charge transport between heterogeneous phases in a 1D composite. [ABSTRACT FROM AUTHOR]

Polymer‐based chalcogenide composites are gaining attention for thermal energy storage thermoelectric (TE) applications due to their high Seebeck coefficient (S) and electrical conductivity (σ), compared to low thermal conductivity of polymers without electrical optimization. This combination can enhance power factor and ZT while suppressing drawbacks. The energy‐filtering effect of polymer/chalcogenide interfaces may also improve TE performance, further enhancing the potential for improved TE applications. In this work, Poly(3,4‐ethylenedioxythiophene) (PEDOT) was functionalized with selenium (Se), and its structural and thermoelectric (TE) properties were studied. The variations of σ and S, with higher percent of Se content, displays a simultaneous rise in both σ and S values, which is noteworthy. The probable reason behind this increment of both σ and S values is due to the improvement in charge transport in the composites due to a percolating network formed between the Se nanoparticles and PEDOT along with the carrier energy filtering interaction between PEDOT and Se. The highest room temperature ZT value obtained is 0.027 for 82 % of Se content in PEDOT, which is comparable with bulk nanostructured organic‐inorganic hybrid composite materials. This work presents an efficient technique for enhancing the TE properties of polymers through inorganic functionalization. [ABSTRACT FROM AUTHOR]

The switching ratio of a thermal switch is a key design parameter, and electrically activated switches based on thermoelectric effects have been reported to produce large switching ratios over a wide range of temperatures. Previous switches based on the Seebeck effect have switching ratios that are limited by the thermoelectric figure-of-merit z T. Perhaps, more importantly, they are limited by their device construction of alternating p-type and n-type materials with soldered junctions. Alternatively, we show that semiconducting polymers with spatially graded doping can offer similar switching ratios due to a volumetric heat absorption effect. This occurs in heavily doped polymers, which exhibit a sharp decrease in the Seebeck coefficient as charge carriers become fully delocalized. Such heat absorption is analogous to the Thomson effect, where heat is locally absorbed due to temperature-dependent variation of the Seebeck coefficient. Here, a theoretical model is derived to solve the 1D heat equation with spatially graded doping, allowing for optimization of the doping profile for a given material system. Four different material systems are compared according to an analysis of reported measurements to determine the upper limit of the switching ratio. A hypothetical Thomson switch based on poly(3,4-ethylenedioxythiophene) doped with ferric tosylate can produce switching ratios up to 12 under a thermal bias of 10 K, a threefold increase compared to a Peltier switch of the same material. Like a Peltier switch, the switching ratio of a Thomson switch diverges under a small thermal bias. Under a large thermal bias, the switching ratio converges toward that of an equivalent Peltier switch. [ABSTRACT FROM AUTHOR]

Using first-principles density functional theory based approach, we investigate the tunability of the thermoelectric properties of perovskite MgSiO3. We find that the thermoelectric properties are strongly correlated with the electronic structure and can, therefore, be modulated with uni-axial tensile and compressive strains. Key thermoelectric parameters, such as the Seebeck coefficient (S), show non-monotonic behavior, displaying large shifts with the application of 1 % uni-axial tensile strain. The relevance of this small strain value also appears in structural distortion of the oxygen octahedra and band convergence in the electronic band structure. The band structure modifications also introduce a strong strain dependence of the relaxation time, as defined within the deformation potential approach. As a result, an improvement of up to 35 % is observed in zT with the application of 1 % tensile strain. Our results highlight a possible new route to improving thermoelectric performance in perovskite oxide thermoelectrics. [ABSTRACT FROM AUTHOR]

The development of new sulfide and selenide-based thermoelectric (TE) materials is critical for the mass production of TE devices due to the higher earth abundance of S/Se than Te. In this work, we have prepared single crystals of Ag-substituted BaCu2−xAgxSe2 (x = 0 – 0.8) by direct fusion of elements at high temperatures. As characterized by single crystal X-ray diffraction (SCXRD) studies, each of the structures (space group: Pnma) contains two transition metal sites (M1 and M2), and the Ag atoms are disordered with Cu atoms at both sites with a slight preference for the M2 site. Phase pure polycrystalline BaCu2−xAgxSe2 (x = 0 – 1.0) samples have also been synthesized, which are semiconductors as confirmed by optical absorption and resistivity studies. All these samples show positive values of the Seebeck coefficient, suggesting the p-type electrical conduction. Our thermal conductivity (ktot) studies demonstrate a remarkable drop in ktot values on increasing the Ag-substitution in the BaCu2−xAgxSe2 phases with the lowest ktot value of 0.33 W m−1 K−1 (673 K) for the x = 1.0 sample. Our studies show the potential of the BaCuAgSe2 for TE applications with higher zT values if the hole concentration of the phase can be fully optimized. [ABSTRACT FROM AUTHOR]

Thermoelectric materials have been widely recognized as a simple approach to harness green energy by converting thermal gradients into electrical energy. However, the intricate interplay between electrical conductivity, Seebeck coefficient, and thermal conductivity in thermoelectric materials presents a challenge to improving their efficiency. Traditional experimental methods and calculation methods have troublesome steps and long cycles for predicting new thermoelectric materials. In this work we present materials informatics-based approach, where statistical and machine learning models like correlation matrix, multiple linear regression, principal component analysis and artificial neural network were employed to find the relationship between features and thermoelectric performance. Furthermore, artificial neural network was used to analyze the roles of several compositional and microstructural features along with temperature on electrical conductivity, thermal conductivity, Seebeck coefficient and thermoelectric figure of merit (ZT) for PANI and quasi 0D carbon-based composites. [ABSTRACT FROM AUTHOR]

Thermoelectrics are critical for sustainable energy development because they allow for the direct conversion of waste heat into electricity, improve energy efficiency in a variety of applications, and provide a clean, dependable, and maintenance- free alternative for power generation. In recent days, metal chalcogenides have gained more attention in the field of thermoelectrics. Among the chalcogenide materials, Tin Selenide is a promising material for mid-temperature thermoelectric applications, whereas Bismuth Telluride is mainly known for its room-temperature thermoelectric applications. The combination of these two materials would probably enhance the performance of the thermoelectric generator. The present work deals with bilayer and multilayer thin film deposition of Tin Selenide and Bismuth Telluride on the glass substrates by physical vapor deposition. Then the deposited thin films were given a post-annealing treatment for 30 minutes at 323 K, 423 K, and 523 K. The structure and morphology of the thin films have been studied using X-Ray Diffraction (XRD), Scanning Electron Microscopy(SEM), Field Emission Scanning Electron Microscopy(FESEM) and Atomic Force Microscopy (AFM). The Seebeck Coefficient and Electrical conductivity of the bilayer and multilayer thin films were studied using the Seebeck Coefficient measurement system as temperature as function in a range of 300K to 573 K. The maximum Seebeck Coefficent of -350μV/K was obtained for both bilayer and multilayer thin film at 573 K. The highest electrical conductivity of 220S/m and 170S/m were obtained for bilayer and multilayer thin film respectively. The power factor that gives the thermoelectric generator's performance was calculated from the Seebeck Coefficient and Electrical conductivity. The overall power factor for 573 K annealed films of bilayer and multilayer thin films increases with rise in temperature. The maximum obtained power factor for bilayer and multilayer thin films were 25W/K2m and 18 W/K2m respectively. An increase in the annealing temperature leads to improved thermoelectric performance for both bilayer and multilayer thin films. [ABSTRACT FROM AUTHOR]

Earth-adequate quaternary chalcogenides like Cu2NiSnS4 with more complex crystal structures can become non-toxic and cost-effective thermoelectric (TE) materials. TE materials, by employing the energy filtering effect through appropriate energy bandgap, have enhanced their TE efficiency. The composition of CuO in Cu2NiSnS4 matrix has enhanced the Seebeck coefficient (S) and declined the thermal conductivity (κ) simultaneously, due to the decrement of carrier concentration (n), by increasing the wt% of CuO in the composites. The highest power factor of 270.88 μW m−1 K−2 at 573 K is recorded for 30 wt% composites. The 30 wt% composite material thermal conductivity exhibited a low value of 0.442 W m−1 K−1 through stronger phonon scattering at the interface boundaries formed between the Cu2NiSnS4 matrix and CuO compositions. A maximum zT of 0.35 for the Cu2NiSnS4/30 wt% CuO composite was obtained, 75% larger than that of the Cu2NiSnS4 matrix at 573 K. This strategy of introducing metal oxides into the metal sulphide matrix for obtaining efficient TE performance could be extended to other eco-friendly quaternary chalcogenides. [ABSTRACT FROM AUTHOR]

This work focuses on the synthesis and properties of quaternary ZnSnP2-yAsy chalcopyrite solid solutions. Full miscibility of the solid solution is achieved using ball milling followed by hot press sintering. The measured electrical conductivity increases substantially with As substitution from 0.03 S cm−1 for ZnSnP2 to 10.3 S cm−1 for ZnSnAs2 at 715 K. Band gaps calculated from the activation energies show a steady decrease with increasing As concentration from 1.4 eV for ZnSnP2 to 0.7 eV for ZnSnAs2. The Seebeck coefficient decreases significantly with As substitution from nearly 1000 μV K−1 for ZnSnP2 to −100 μV K−1 for ZnSnAs2 at 650 K. Thermal conductivity is decreased for the solid solutions due to alloy phonon scattering, compared to the end members with y = 0 and y = 2, with the y = 0.5 and y = 1.0 samples exhibiting the lowest values of 1.4 W m−1 K−1 at 825 K. Figure of merit values are increased for the undoped solid solutions at lower temperatures when compared to the end members due to the decreased thermal conductivity, with the y = 0.5 sample reaching zT = 1.6 × 10−3 and y = 1 reaching 2.1 × 10−3 at 700 K. The largest values of the figure of merit zT for the undoped series was found for y = 2 with zT = 2.8 × 10−3 at 700 K due to the increasing n-type Seebeck coefficient. Boltztrap calculations reveal that p-doping could yield zT values above unity at 800 K in case of ZnSnAs2, comparable with ZnSnP2. [ABSTRACT FROM AUTHOR]

Recently, thermoelectric (TE) materials have seized great attention for their role in clean energy conversion applications. Cu2S are p-type super-ionic conductors featuring a narrow band gap of 1.7 eV while exhibiting outstanding thermoelectric characteristics. The Cu2S matrix and the CuO nanoinclusions were successfully synthesized via solvothermal and hydrothermal routes, respectively. The morphological observations made through scanning and transmission electron microscope ensured the homogeneous distribution of CuO nanoinclusions in the Cu2S matrix, hence, the formation of standard Cu2S/CuO composites. In this work, we have introduced a "combined strategy" to boost the figure of merit (zT). The Seebeck coefficient reached the maximum of 271.86 μVK−1 at 573 K for the 20 wt% CuO sample (a 71.45% gain when compared to the pure Cu2S) owing to the filtration of low-energy carriers at the CuO potential barriers (2.5 eV). The Cu2S/20 wt% CuO sample achieved the minimum thermal conductivity values. At 573 K, We recorded a vast power factor value of 952.66 μWm−1 K−2 (32.23% gain) for the Cu2S/15 wt% CuO sample. These values are vastly higher than previously reported for the copper sulfides-based TE materials. Consequently, an optimised zT value of 0.44 (214.29% gain) was accomplished for the Cu2S/15 wt% CuO sample at 573 K. The strategy presented in our study can also be extended to other TE materials, especially for the promising copper chalcogenides to improve their zT values. [ABSTRACT FROM AUTHOR]

This study describes a method by which to synthesize SiO2-based graphene nanoballs (SGB) using atmospheric pressure chemical vapor deposition (APCVD) with copper vapor assistance. This method should solve the contamination, damage, and high costs associated with silica-based indirect graphene synthesis. The SGB was synthesized using APCVD, which was optimized using the Taguchi method. Multiple synthesis factors were optimized and investigated to find the ideal synthesis condition to grow SGB for thermoelectric (TE) applications. Raman spectra and FESEM-EDX reveal that the graphene formed on the silicon nanoparticles (SNP) is free from copper. The prepared SGB has excellent electrical conductivity (75.0 S/cm), which shows better results than the previous report. Furthermore, the SGB nanofillers in bismuth telluride (Bi2Te3) nanocomposites as TE materials exhibit a significant increment in Seebeck coefficients (S) compared to the pure Bi2Te3 sample from 109 to 170 μV/K at 400 K, as well as electrical resistivity decrement. This approach would offer a simple strategy to improve the TE performance of commercially available TE materials, which is critical for large-scale industrial applications. [ABSTRACT FROM AUTHOR]

This study examined the potential consequences of doping on Sr2YGaX2O7(X = Fe, Rh) photovoltaic properties. Density functional theory (DFT) was used to calculate pyrochlore oxides' energy band structure and optical characteristics using the full potential linearized augmented plane wave (FP-LAPW) method. The generalized gradient approximation (GGA + U) was utilized to treat the exchange and correlation potential. We studied the metallic atoms Fe, Rh, Y, and Ga orbital electronic states. The utilization of the complex dielectric function facilitated the computation of various optical properties such as the energy band dispersion statistics, absorption coefficient, reflectivity, energy loss function, refractive index, extinction coefficient, and real optical conductivity parameters. We employed Boltzmann transport theory to delve deeper into the electrical transport characteristics (specifically thermoelectric properties) of Fe and Rh-doped pyrochlore oxides in the temperature range of 0–800 K. It is observed that the Sr2YGaRh2O7 compound indicated higher values of ZT 0.9, 1.25 for 50 K and 800 K, respectively. Further, both the compounds exhibit p-type nature as their seebeck coefficient shows a positive region between 50 and 800 K. The materials with strong thermoelectric properties are assumed in high reflectivity zone and potentially effective in solar heating. [ABSTRACT FROM AUTHOR]

Calcium titanium oxide has emerged as a highly promising material for optoelectronic devices, with recent studies suggesting its potential for favorable thermoelectric properties. However, current experimental observations indicate a low thermoelectric performance, with a significant gap between these observations and theoretical predictions. Therefore, this study employs a combined approach of experiments and simulations to thoroughly investigate the impact of structural and directional differences on the thermoelectric properties of two-dimensional (2D) and three-dimensional (3D) metal halide perovskites. Two-dimensional (2D) and three-dimensional (3D) metal halide perovskites constitute the focus of examination in this study, where an in-depth exploration of their thermoelectric properties is conducted via a comprehensive methodology incorporating simulations and experimental analyses. The non-equilibrium molecular dynamics simulation (NEMD) was utilized to calculate the thermal conductivity of the perovskite material. Thermal conductivities along both in-plane and out-plane directions of 2D perovskite were computed. The NEMD simulation results show that the thermal conductivity of the 3D perovskite is approximately 0.443 W/mK, while the thermal conductivities of the parallel and vertical oriented 2D perovskites increase with n and range from 0.158 W/mK to 0.215 W/mK and 0.289 W/mK to 0.309 W/mK, respectively. Hence, the thermal conductivity of the 2D perovskites is noticeably lower than the 3D ones. Furthermore, the parallel oriented 2D perovskites exhibit more effective blocking of heat transfer behavior than the perpendicular oriented ones. The experimental results reveal that the Seebeck coefficient of the 2D perovskites reaches 3.79 × 102 µV/K. However, the electrical conductivity of the 2D perovskites is only 4.55 × 10−5 S/cm, which is one order of magnitude lower than that of the 3D perovskites. Consequently, the calculated thermoelectric figure of merit for the 2D perovskites is approximately 1.41 × 10−7, slightly lower than that of the 3D perovskites. [ABSTRACT FROM AUTHOR]

Organic thermoelectric (TE) materials are regarded as the next‐generation TE materials because of their merits including low cost, high mechanical flexibility, and low intrinsic thermal conductivity. However, their Seebeck coefficient is usually quite low. Herein, a new strategy is demonstrated to greatly enhance the Seebeck coefficient of poly(3,4‐ethylenedioxy‐thiophene):poly(styrenesulfonate) (PEDOT:PSS), which is the most popular TE polymer, through polaron level splitting via π–π overlapping with nonpolar small aromatic molecules including anthracene, naphthalene, and pyrene. Although these aromatic molecules are neither oxidizing nor reducing agent, they can greatly enhance the Seebeck coefficient of PEDOT:PSS films pre‐treated with dimethyl sulfoxide, acid, or acid then base, while they do not lower the electrical conductivity too much. Through such a treatment with anthracene, the Seebeck coefficient can be up to 45.5 µV K−1, and the ZT value can be up to 0.27. The enhancement is ascribed to the splitting of the lower polaron energy level of PEDOT, which is induced by the π–π overlapping between the aromatic compounds and conjugated PEDOT. This can shift up the Fermi level, thereby enhancing the Seebeck coefficient. [ABSTRACT FROM AUTHOR]

The field of electronic textiles currently lacks n‐type polymer fibers that can complement the more established p‐type polymer fibers. Here, a highly conductive n‐type polymer fiber is obtained via wet‐spinning of n‐doped poly(3,7‐dihydrobenzo[1,2‐b:4,5‐b']difuran‐2,6‐dione) (n‐PBDF). The electrical conductivity of the fibers increases from 1000 to 1600 S cm−1 with increased draw during processing and correlates well with Young's modulus. Wide‐angle X‐ray scattering reveals the existence of a bimodal orientation of the polymer chains, favoring parallel alignment to the fiber axis with increased draw. After 14 d in 80% humid air, fiber conductivity stabilizes maintaining 81% of the initial conductivity. Although the electrical conductivity drops slightly over time, the Seebeck coefficient increases, resulting in the highest thermoelectric power factor being measured at 91 µW m−1 K−2 for the most drawn fiber 14 d after its fabrication. A proof‐of‐concept two‐couple thermoelectric textile is crafted by embroidering bundles of n‐type PBDF fibers and p‐type PEDOT:PSS fibers. The device generates 2.40 nW at a 22 °C temperature gradient. This work represents the initial steps and a crucial advancement toward fabricating high‐performance n‐type polymer fibers that can complement their p‐type counterparts to close the existing performance gap. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials have attracted attention for offering a green option for power generation, due to their ability to convert thermal energy into electricity. In recent years, a promising way to achieve efficiency in TE properties has been proposed based on composites of conjugated polymers, such as polyaniline (PANI), and carbon nanomaterials such as graphene (GR). Since polyaniline and GR composites are promising fillers for organic thermoelectric materials (OTE), we expanded their investigations for a ternary system (TS), providing materials with multiple functionalities, and high performance. In this research work, a TS based on an acrylic matrix (ACR), GR, and PANI was successfully prepared through the combination of in situ polymerization of aniline in contact with GR and mechanical mixture of the resulting hybrid with an ACR. Structural and morphological characterization confirmed that GR affected PANI morphology and crystallinity. The band gap determination by Tauc's relation indicated the occurrence of π‐π interaction between the chains and an increase of the electrical conductivity of the composites allowed to infer a synergistic effect. The measured Seebeck coefficient reached a maximum value of −17.02 μVK−1 and the highest power factor obtained was 4.94 μWm−1 K−2 for the ACR/PANI sample, indicating a material with promising thermoelectric properties. [ABSTRACT FROM AUTHOR]

Electronegative S-filled skutterudite compounds have attracted considerable attention due to scattering of low-frequency phonons (35–50 cm − 1 ), but there are few reports on S-filled double-substituted skutterudite. In this work, a series of S-filled Te-Sn double-substituted skutterudite compounds were synthesized using high pressure and high temperature (HPHT) method. The phase composition, microstructure, and thermoelectric properties of SxCo4Sb 1 1 Te 0. 7 Sn 0. 3 (x = 0 , 0.05, 0.10, 0.20) samples were systematically determined. The results show that the introduction of S increases the substitution limit of Te in the Sb site. Under the combined effect of the sample synthesis pressure and S filling, the nucleation density of the sample grains increases and the grain size decreases. At the same time, there are numerous special microstructures in the samples synthesized in a high-pressure environment. Thermoelectric performance studies show that a small amount of S filling optimizes the Seebeck coefficient of the sample and increases the power factor (PF). With an increase of the amount of S introduced, the thermal conductivity of the samples decreases significantly. Therefore, the maximum zT value of an S 0. 0 5 Co4Sb 1 1 Te 0. 7 Sn 0. 3 sample synthesized at 2.5 GPa pressure is 0.17 at room temperature. The maximum zT value of the sample is 1.26 at 773 K. [ABSTRACT FROM AUTHOR]

Uniform dispersion of nanosized secondary phases in bulk thermoelectric materials has proven to be an effective strategy to reduce the lattice part of thermal conductivity and improve the thermoelectric efficiency. In this work, reduced graphene oxide (rGO) was uniformly dispersed in the In0.5Co4Sb12 bulk material by ultrasonication. The formation of impurity phases of InSb and CoSb2 in the In-filled Co4Sb12 is inevitable, as observed from XRD and EPMA analyses. The Raman spectra of the nanocomposites showed broad peaks suggesting phonon softening and additional peaks corresponding to rGO. Electron transport was not affected by rGO addition, resulting in little change in the electrical resistivity and Seebeck coefficient. The lattice thermal conductivity of the bulk material was significantly reduced by the addition of a small amount of rGO, primarily attributed to the interface scattering of phonons. Hence, the highest zT of ∼1.53 at 773 K was achieved for the In0.5Co4Sb12/0.25 vol% rGO composite in the temperature range from 723 K to 773 K. [ABSTRACT FROM AUTHOR]

ZnO is a promising high‐temperature thermoelectric (TE) material due to its superior stability and earth abundance. However, the coupling relation between Seebeck coefficient and electrical conductivity on carrier concentration limits the optimum TE performance for most TE materials, especially ZnO. Herein, enhancement of TE performance is achieved via a stepwise optimization strategy composed of carrier concentration optimization and carrier filtering effect for fabricating robust ZnO‐based composite ceramics through a self‐developed specific high‐pressure synthesis followed by spark plasma sintering. Specifically, doping SnO2 provide substantial electrons to surge the carrier concentration. The subsequent compositing Si3N4 nanoparticles results in the unique reaction‐generated Zn2SiO4 nanoprecipitates with a larger bandgap and intrinsically low thermal conductivity, which introduce an excellent carrier filtering effect to increase the Seebeck coefficient by 57.7% at 300 K without compromising electrical conductivity much and enhance phonon scattering to cause an ultralow lattice thermal conductivity of 1.39 W m−1 K−1 achieving amorphous limits of ZnO (1.4±0.1 W m−1 K−1). Consequently, a high peak ZT (figure of merit) of 0.691 at 873 K is obtained, which is higher than that of previously reported ZnO‐based TE materials. This work demonstrates a feasible and effective strategy to fabricate high‐performance TE materials, especially those with inferior electrical conductivity. [ABSTRACT FROM AUTHOR]

In this study, we compare the thermoelectric properties of coarse-grained n-type Bi2Te2.55Se0.45 alloy prepared by induction melting with the bulk-nanostructured prepared by ball milling and hot-pressing techniques. The corresponding thermoelectric properties showed different behavior for each material processed using different routes. The most striking result of the study is observing a p-type behavior and charge carrier transition from p-to n-type for the coarse-grained alloy. These observed phenomena are related mainly to the unique needle-like microstructure accompanied by high lattice strain. Lastly, the obtained figure-of-merit values for the coarse needle-like structure and bulk nanostructured Bi2Te2.55Se0.45 alloys are 0.20 and 0.80 at their optimum temperatures of 60 and 120 °C, respectively.

A small organic molecule (SOM), 2,2′-(3,3′′-dihexyl-[2,2′:5′,2′′-terthiophene]-5,5′′-diyl)bis(1-octyl-1H-phenanthro[9,10-d]imidazole) (1), was utilised as an additive to intercalate with reduced graphene oxides (rGOs–1) in a single walled-carbon nanotube (SWCNT) composite. The ternary composite formed by incorporating rGOs–1 into the SWCNTs exhibited improvements in thermoelectric (TE) and carrier transport properties through the strong interfacial π–π interaction between the rGOs–1 and SWCNTs. The SOM 1 hybridised with the SWCNT composite induced significant interfacial phonon scattering, resulting in a reduction in the thermal conductivity (κ) of the SWCNT composite with rGOs–1. As a result, the SWCNT composite incorporating rGOs–1 demonstrated a simultaneous improvement of the Seebeck coefficient by 15% and a reduction in κ by 32%, resulting in an enhancement in the TE figure of merit (6.8 ± 0.7 × 10−3 at 297 K), which was 2.3 times higher than that of the SWCNTs alone (2.9 ± 0.5 × 10−3). [ABSTRACT FROM AUTHOR]

This work is devoted to the development of epoxy-encapsulated zinc oxide-multiwalled carbon nanotubes (ZnO–MWCNT) hybrid nanostructured composites and the investigation of their thermoelectric performance in relation to the content of MWCNTs in the composite. For the preparation of nanocomposites, self-assembling Zn nanostructured networks were coated with a layer of dispersed MWCNTs and subjected to thermal oxidation. The resulting ZnO–MWCNT hybrid nanostructured networks were encapsulated in commercially available epoxy adhesive. It was found that encapsulation of ZnO–MWCNT hybrid networks in epoxy adhesive resulted in a simultaneous decrease in their electrical resistance by a factor of 20–60 and an increase in the Seebeck coefficient by a factor of 3–15, depending on the MWCNT content. As a result, the thermoelectric power factor of the epoxy-encapsulated ZnO–MWCNTs hybrid networks exceeded that of non-encapsulated networks by more than 3–4 orders of magnitude. This effect was attributed to the ZnO–epoxy interface's unique properties and to the MWCNTs' contribution. The processes underlying such a significant improvement of the properties of ZnO–MWCNT hybrid nanostructured networks after encapsulation in epoxy adhesive are discussed. In addition, a two-leg thermoelectric generator composed of epoxy-encapsulated ZnO–MWCNT hybrid nanocomposite as n-type leg and polydimethylsiloxane-encapsulated CuO–MWCNT hybrid nanocomposite as p-type leg characterized at room temperatures showed better performance at temperature difference 30 °C compared with the similar devices, thus proving the potential of the developed nanocomposites for applications in domestic waste heat conversion devices. [ABSTRACT FROM AUTHOR]

The thermoelectric (TE) characteristics of polyvinyl alcohol/poly (3,4-ethylenedioxy thiophene)/titanium carbide (PVA/PEDOT/TiC) composites were explored in this work. The composite films with varying TiC weight ratios were made using the solvent casting process. The homogeneous distribution of TiC particles in the composite structure was revealed by SEM micrographs. The presence of TiC particles in the crystallinity of PVA/PEDOT was revealed by XRD patterns. The electrostatic interactions in the composite structure were revealed by FTIR-ATR studies. The electrical conductivity of PVA/PEDOT rose from 0.06 S/cm to 1.15 S/cm with the contribution of 5% TiC, while the Seebeck coefficient increased from 3.9 µV/K to 98.8 µV/K with the contribution of 1% TiC, according to TE studies. The composite samples exhibited a maximum power factor of 0.72 µW/mK2, which is 104 times greater compared to PVA/PEDOT. [ABSTRACT FROM AUTHOR]

This work aims to study the optoelectronic and thermoelectric properties of the new perovskites LiSnX3 (X = Br or I). This study is carried out by using the density functional theory (DFT) combined with the Boltzmann transport theory. First, the investigation of the structural, electronic and optical properties of such materials, using the Generalized Gradient Approximation (GGA), has been performed. This latter method has been performed under the Perdew–Burke–Ernzerhof (GGA–PBE) approximation applying the exchange correlation potential. It is found that the two compounds exhibit a p-type semiconductor characteristic and interesting optical properties. Moreover, the thermoelectric properties of the studied materials, such as the Seebeck coefficient, electrical conductivity, thermal conductivity, figure of merit and power factor, have been examined. It is found that the Seebeck coefficient takes positive values. This finding reveals and confirms the p-type semiconductor characteristic for two studied compounds. On the other hand, such materials display large values of the figure of merit (ZT) in comparison with the existing thermoelectric materials. Such large values of ZT are found for both small or large temperature values. The obtained results of the optoelectronic and thermoelectric properties show that these materials could be useful both for photovoltaic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

In this study, the electrical and optical properties of the piperic acid (PA)-filled polyaniline-HCl (PANI-HCl) composites (PANI-HCl/PA) were investigated. For this purpose, the composites containing different weight ratios of PA were prepared by the oxidative chemical polymerization of PANI-HCl. The studies on the optical properties of the pristine PANI-HCl and the composites showed that the bandgap of the PANI-HCl reduced from 2.510 to 2.490 eV with the addition of 3% PA. Additionally, significant alterations such as redshift, improved polarizability, and tuned refractive were observed. From the thermoelectric analyses, it was obtained that the electrical conductivity of the pristine PANI-HCl increased from 0.042 up to 37.5 Scm−1 while the Seebeck coefficient increased from 10.1 up to 49.1 µVK−1. The thermoelectric power factor of the composites reached the maximum at 3.91 µWm−1K−2, which is approximately 104 times higher compared to the pristine PANI-HCl. Given the significant changes such as redshift, band gap narrowing, improved polarizability, tuned refractive index, and enhanced thermoelectric performance, this study suggests that the composites prepared in this study could be used as efficient materials for the design and development of UV shielding and thermoelectric materials. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 has been extensively used because of its excellent thermoelectric properties at room temperature. Here, 230–420 nm of Bi 2 Te 3 hexagonal nanosheets has been successfully synthesized via a "green" method by using ethylene glycol solution and applying polyvinyl pyrrolidone (PVP) as a surfactant. In addition, factors influencing morphological evolution are discussed in detail in this study. Among these parameters, the reaction temperature, molar mass of NaOH, different surfactants, and reaction duration are considered as the most essential. The results show that the existence of PVP is vital to the formation of a plate-like morphology. The reaction temperature and alkaline surroundings played essential roles in the formation of Bi 2 Te 3 single crystals. By spark plasma sintering, the Bi 2 Te 3 hexagonal nanosheets were hot pressed into solid-state samples. We also studied the transport properties of solid-state samples. The electrical conductivity σ was 18.5 × 10 3 Sm − 1 to 28.69 × 10 3 Sm − 1 , and the Seebeck coefficient S was −90.4 to −113.3 µVK − 1 over a temperature range of 300–550 K. In conclusion, the observation above could serve as a catalyst for future exploration into photocatalysis, solar cells, nonlinear optics, thermoelectric generators, and ultraviolet selective photodetectors of Bi 2 Te 3 nanosheet-based photodetectors. [ABSTRACT FROM AUTHOR]

Context: We comparatively investigate the properties of pure ZnO and 2 at. % Al doping concentration of ZnO, AZO, as potential candidates for specific applications. Methods: Calculations were carried out, using Wien2k package, to deduce structural, electronic, optical thermoelectric, and properties of both ZnO and AZO materials via the combination of GGA and mBJ approximations. Results: It is shown that Al doping of ZnO (AZO) improves its optical properties; the deduced direct fundamental gap is enhanced due to the Burstein–Moss effect. Moreover, the dielectric function, at lower energies, confirms the existence of an extra strong fluctuation in the dispersive real part ɛ1(ω) and a high peak for absorptive imaginary parts ɛ2(ω) which are due to a variation in specific molecular bonding and the transition between the occupied and the non-occupied states. The critical point, observed at 2.81 eV for pure ZnO, is shifted to 3.3 eV in 2 at. % AZO, confirming a larger optical band gap. The reflectivity values slightly decreased for 2% AZO. The investigation of thermoelectric parameters as a function of chemical potential at different temperatures ranging from 300 to 900°C showed that these structures can be considered for good thermoelectric devices with (i) high absolute values of Seebeck coefficient: ׀SZnO׀ = 1.16 mV/K and ׀SAZO׀ = 0.746 mV/K, (ii) no effect of temperature on electrical conductivity but a strong effect on thermal conductivity, (iii) a high value approaching unity for the figure of merit. Hence, these properties and their improvements, introduced by Al doping of ZnO, lead specific and more uses in optoelectronics, energy, and piezoelectric applications. [ABSTRACT FROM AUTHOR]

Harvesting low‐grade waste heat from the natural environment with thermoelectric materials is considered as a promising solution for the sustainable energy supply for wearable electronic devices. For practical applications, it is desirable to endow the thermoelectric materials with excellent mechanical and self‐healing properties, which remains a great challenge. Herein, the design and characterization of a series of high‐performance ionic hydrogels for soft thermoelectric generator applications are reported. Composed of a physically cross‐linked network of polyacrylic acid (PAA) and polyethylene glycol (PEO) doped with sodium chloride, the resulting PAA‐PEO‐NaCl ionic hydrogels demonstrates impressive mechanical strength (breaking stress >1.3 MPa), stretchability (>1100%), and toughness (up to 7.34 MJ m−3). Moreover, the reversible hydrogen bonding interaction and chain entanglement render the ionic hydrogels with excellent mechanical resilience, adhesion properties, and self‐healing properties. At ambient conditions, the electrochemical and thermoelectric performance of the ionic hydrogels can be restored immediately from physical damage such as cutting, and the mechanical healing can be completely restored within 24 h. At the optimized composition, the Seebeck coefficient of the ionic hydrogels can reach 3.26 mV K−1 with a low thermal conductivity of 0.321 W m−1 K−1. Considering the excellent mechanical properties and thermoelectric performance, it is believed that the ionic hydrogels are widely applicable in ionic thermoelectric capacitors to convert low‐grade heat into electricity for soft electronic devices. [ABSTRACT FROM AUTHOR]

This paper explores the photovoltaic and thermoelectric properties of composites consisting of NaSnX3 (X = Br or I). The study uses density functional theory in conjunction with the Boltzmann Transport Theory. Initially, the structural, electronic, and optical properties of the materials are inspected using the generalized gradient approximation (GGA) based on the Perdew–Burke–Ernzerhof approximation (GGA-PBE) with consideration of the cross-correlation potential. The findings reveal that the studied compounds exhibit a p-type semiconductor character along with intriguing optical properties. Afterward, the thermoelectric properties of the materials are examined and discussed in the second part of the study. This analysis includes the Seebeck coefficient, electrical and thermal conductivities, the figure of merit, and the power factor. It is observed that the Seebeck coefficient demonstrates positive values, confirming the p-type semiconducting properties of the two materials under study. Additionally, these compounds exhibit significant values of the figure of merit (ZT) values when compared to existing thermoelectric materials. Especially, the large ZT values are achieved at both low and high-temperature ranges. Generally, these materials hold potential for applications in photovoltaic and/or thermoelectric fields. [ABSTRACT FROM AUTHOR]

The electrodeposition of bismuth--tellurium thermoelectric material was investigated by galvanostatic and potentiostatic electrolysis in ethylene glycol (EG)-BiCl3--TeCl4 non-aqueous solutions at 393 K. Controlling the molar ratio of BiCl3 to TeCl4 in the bath and the electrolysis conditions, the Bi--Te alloys with various compositions were electrodeposited. The composition of the electrodeposit obtained in the 97.50 mol%EG-2.45 mol%BiCl3--0.05 mol%TeCl4 bath with the BiCl3 to TeCl4 molar ratio of 50:1 at the current density of 20 A⋅m-2 was 40.14 mol%Bi--59.86 mol%Te and close to that of Bi2Te3. This electrodeposit exhibited a n-type thermoelectric conversion for the given temperature difference and its Seebeck coefficient was -145µVK-1. [ABSTRACT FROM AUTHOR]

High thermoelectric (TE) power factors were obtained for bismuth telluride by deploying confinement and multi-scale engineering in synergy. The thickness of the film was kept in the ultra-thin range (41 nm) following which a high magnitude of 1.9 × 104 S m−1 was obtained at room temperature (RT). Films were deposited at an elevated substrate temperature to enhance the grain quality and high mobility bearing (00l) grain growth. Thus, relatively large crystallite sizes (∼26 nm) with less grain boundaries and directional growth with a low defect profile were the prime reasons for highly enhanced electrical conductivity. Apart from the multiple effects that were deployed, ultra-thin dimensions of the films proved to be effective in further enhancing Seebeck coefficient values. The co-alloyed In minimized the hole concentration through reducing antisite defects and also preserved the reduced bipolar effect at elevated temperatures. The inclusion of excess tellurium induced Te segregates in the film that helped in energy dependent scattering of carriers in addition to its donor-like effect. Hot carrier filtering, induced by excess Te along with ultra-thin dimensions resulted in a Seebeck coefficient (S) of −223.6 μV K−1 at RT. A soaring value of −338.1 μV K−1 was obtained at 90 °C. Following the synergetic employment of multiple enhancement strategies, a high power factor of 959.9 μW m−1 K−2 was obtained at room temperature with a towering magnitude of 2537.7 μW m−1 K−2 at 90 °C. [ABSTRACT FROM AUTHOR]

A model of the thermoelectric transport properties of hot extruded bulk polycrystalline (HEBP) n-type Bi2Te3 has been developed based on the marked anisotropy of its properties induced by extrusion. HEBP Bi2Te3 is a highly textured material that allows treating electrical and thermal transport in the plane perpendicular to the extrusion axis as approximately isotropic. The model of this transport is based on the simplified electronic density of states suggested by ab initio calculations of the band structure of crystalline Bi2Te3 near the band edges. The proposed model can also be applied to transport along the extrusion axis in a temperature range when there is only one limiting charge carrier scattering mechanism. It provides excellent accord to the Hall effect (perpendicular) and the Harman (along extrusion) measurement of mobility, and the Seebeck coefficient of HEBP n-type Bi2Te3 in the temperature range from ∼200 to 460 K. It can be concluded that acoustic phonon scattering provides the limiting scattering mechanism for this temperature range. The model is also applied to elucidate the important role of thermodiffusion, suggesting that the usual approach to experimentally obtain this contribution to the thermal conductivity can only give approximate rough estimates. [ABSTRACT FROM AUTHOR]

In the present work, we have obtained high magnitudes of the Seebeck coefficient in Sb and In coalloyed bismuth telluride thin film that has been deposited by a simple and cost-efficient thermal evaporation procedure. The films display an exceptional peak Seebeck coefficient of −310 μV/K at the working temperature of 90 °C. In addition to this, a high value of −191.6 μV/K is obtained at room temperature along with appreciable conductivity (6.2 × 103 S/m). The x-ray diffraction (XRD) pattern of the film has been analyzed for probing the crystal profile that depicts a polycrystalline and nanoscale structure. Films' surface and cross-sectional morphologies are investigated using Field Emission Scanning Electron Microscope (FESEM), where a nanocrystalline morphology of thickness 150 nm is observed. Raman analysis supports the results obtained from XRD and FESEM for nanomorphology and indicates the presence of Te segregates. Atomic composition of the film produced is probed using Energy Dispersive x-ray spectroscopy, which also indicates the presence of excess Te. The Seebeck coefficient of the films shows an enormous enhancement as compared to previously reported work for undoped samples (BST-100S). The magnitudes of the Seebeck coefficient obtained in the present work are among the highest values reported for a bismuth antimony telluride material. These enhancements are attributed to the combined effect of coalloying, the presence of highly mobile (00l) orientations, and confinement effects of a nanocrystalline profile. [ABSTRACT FROM AUTHOR]

Incorporating inorganic nanomaterials into a polymer matrix is one of the most effective ways to create thermoelectric performance for applications where physical flexibility is essential. In this study, flexible thermoelectric nanocomposite films were synthesized by incorporating inorganic copper iodide (CuI) nanosheets as the filler into poly (3,4-ethylene dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS). The process involved the preparation of bulk CuI from precursors and, subsequently, the nanosheet synthesis by dissolving the bulk CuI in dimethyl sulfoxide (DMSO). The morphology of the nanosheets and the nanocomposite films was thoroughly examined, and the film's thermoelectric performance was evaluated using a standard thermoelectric measurement system, ZEM-3. The morphological observation revealed a triangular nanosheet geometry for CuI, with an average lateral dimension of ~33 nm. The PEDOT/CuI nanocomposite films were prepared by mixing CuI nanosheets with PEDOT: PSS through ultrasonication and filtration on a PVDF membrane. The film with 6.9 vol% of CuI nanosheets exhibited an electrical conductivity and Seebeck coefficient of 852.07 S·cm-1 and 14.95 µV·K-1, respectively. This resulted in an enhanced power factor of 19.04 µW·m-1·K-2, much higher than the individual composite components. It demonstrated a trend of increasing power factor with the nanosheets up to 6.9 vol% due to improved electrical conductivity. The increase in electrical conductivity can be attributed to the screening effect induced by DMSO, which leads to a conformational change in the PEDOT chains. Furthermore, an optimal fraction of CuI nanosheets also contributes to this conformational change, further enhancing the electrical conductivity. [ABSTRACT FROM AUTHOR]

A fully automated experimental system was designed for simultaneous measurement of the Seebeck coefficient and electrical resistivity of thermoelectric materials in bulk form. The system incorporates a straightforward and easily fabricated sample holder along with commercially available electronic instrument components. The sample holder showcases a compact design that utilizes two Peltier module heaters to induce sample heating and generate the required temperature gradient. System automation and control are achieved through the implementation of a LabView program. The Seebeck voltage and resistance of the sample (under specified temperature conditions) are determined using I–V measurements. The Seebeck voltage and resistance of the sample correspond to the intercept and slope of the I–V characteristic diagram in the four-point probe method, respectively. To verify the accuracy and reliability of the developed apparatus, a variety of experiments were performed on N-type and P-type bismuth telluride samples. The measurement results closely matched those obtained from commercial systems, with an overall data difference of less than 10% for both the Seebeck coefficient and resistivity measurements. [ABSTRACT FROM AUTHOR]

Copper (I) sulfide (Cu2S) is a low-cost, earth-abundant, and non-toxic thermoelectric material for applications in the middle–high temperature range (>650 K). Although 3D printing these materials can simplify their manufacturing, elevated temperatures observed during sintering impair their crystal structure and energy conversion efficiency. In this study, we demonstrated a novel post-processing methodology to revert the thermoelectric properties of the 3D printed Cu2-xS materials back to the unimpaired state via sulfur infusion. After printing and sintering, sulfur was infused into the specimens under vacuum to optimize their crystal structure and achieve high thermoelectric efficiency. Chemical analysis and X-ray Diffraction (XRD) tests showed that after the sulfur infusion process, the Cu/S ratio was reverted close to the stoichiometric level. The 3D printed Cu2-xS showed p-type thermoelectric behavior with electrical conductivity peaking at 143 S-cm−1 at 750 K and Seebeck coefficient of 175 µV-K−1 at 627 K. The figure of merit (ZT) value of 1.0 at 780 K was achieved, which is the highest value ever reported for a 3D printed Cu2-xS thermoelectrics at this temperature. The fabrication of environmentally friendly thermoelectric materials with extended dimensional freedom and conversion efficiency has the potential to impact the thermoelectric industry with new energy conversion applications and lowered manufacturing costs. [ABSTRACT FROM AUTHOR]

The study of molecular nanoelectronic devices has recently gained significant interest, especially their potential use as functional junctions of molecular wires. Aromatic systems with π -conjugated bonds within their chemical backbones, such as catechol, have attracted particular attention in this area. In this work, we focused on calculating and determining catechol's electrical and thermal transport properties using the theoretical method of Green's functions renormalized in a real space domain within a framework of tight-binding approximation to the first neighbors. Thus, we studied two theoretical models of catechol as a function of its geometry, obtaining striking variations in the profiles of electrical and thermal conductance, the Seebeck coefficient, and the figure of merit. The analyses of the results suggest the potential application of catechol as a likely conductive and thermoelectric molecule serving as a novel material to use in molecular electronic devices. [ABSTRACT FROM AUTHOR]

Taking into consideration the research that has been conducted on the optical and electrical properties of molecular systems, especially the good thermoelectric energy conversion at a nanometric scale that such systems have presented, here we present a new alternative by using a particular diphenyl-ether molecule as a functional device. Such a molecular system is modeled as a planar segment coupled to two electrodes in the first-neighbor approximation within a tight-binding Hamiltonian. We study the electrical and thermal properties of diphenyl-ether molecules such as the electric current, electrical and thermal conductance, Seebeck coefficient, and figure of merit, in the strong and weak coupling regimes, considering different structural configurations and variations with temperature. Our results could be valuable for laboratory applications and/or verification since we characterize the diphenyl-ether molecule as a semiconductor device for different structural models. [ABSTRACT FROM AUTHOR]

As a remarkable multifunctional material, ferroferric oxide (Fe3O4) exhibits considerable potential for applications in many fields, such as energy storage and conversion technologies. However, the poor electronic and ionic conductivities of classical Fe3O4 restricts its application. To address this challenge, Fe3O4 nanoparticles are combined with graphene oxide (GO) via a typical hydrothermal method, followed by a conductive wrapping using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic sulfonate) (PEDOT:PSS) for the fabrication of composite films. Upon acid treatment, a highly conductive porous Fe3O4@RGO/PEDOT:PSS hybrid is successfully constructed, and each component exerts its action that effectively facilitates the electron transfer and subsequent performance improvement. Specifically, the Fe3O4@RGO/PEDOT:PSS porous film achieves a high specific capacitance of 244.7 F g−1 at a current of 1 A g−1. Furthermore, due to the facial fabrication of the highly conductive networks, the free-standing film exhibits potential advantages in flexible thermoelectric (TE) materials. Notably, such a hybrid film shows a high electric conductivity (σ) of 507.56 S cm−1, a three times greater value than the Fe3O4@RGO component, and achieves an optimized Seebeck coefficient (S) of 13.29 μV K−1 at room temperature. This work provides a novel route for the synthesis of Fe3O4@RGO/PEDOT:PSS multifunctional films that possess promising applications in energy storage and conversion. [ABSTRACT FROM AUTHOR]

In recent years, the application of ionic thermoelectric (TE) materials to convert low‐grade waste heat into electricity has become a subject of intense scientific research. However, most of the efforts are focused on organic polyelectrolytes or ionic‐liquids embedded in polymeric gels. Here, for the first time, it is demonstrated that nanofluidic membranes of reconstructed layered materials like vanadium pentoxide (V2O5) exhibit excellent ionic‐TE characteristics. The high Seebeck coefficient (S = 14.5 ± 0.5 mV K‐1) of the V2O5 membrane (VO‐M) is attributed to temperature gradient‐induced unidirectional transport of protons through the percolated network of 2D nanofluidic channels. The TE characteristics of VO‐M show nearly 80% improvement (S = 26.3 ± 0.7 mV K‐1) upon functionalizing its percolated network with ionic polymers like poly(4‐styrenesulfonic acid) (PSS). Further, unlike organic polymer‐based TE systems, VO‐M not only sustains exposure to high temperatures (≈200 °C, 5 min) but also protects the PSS molecules intercalated into its interlayer space. Moreover, V2O5‐based TE materials can self‐repair any damage to their physical structure with the help of a tiny water droplet. Thus, nanofluidic membranes of reconstructed layered materials like VO‐Ms demonstrate vast robustness and great ionic‐TE performance, which can provide a novel platform for scientific studies and futuristic applications. [ABSTRACT FROM AUTHOR]