First-principles insights into the structural, optoelectronic, and thermoelectric properties of lead-free halide double perovskites Rb2AlAgX6 (X = Cl, Br, I) for energy applications.

(Bi 2 Te 3 ) x (Sb 2 Te 3 ) 1- x thin films were synthesized using the pressure-gradient-sputtering (PGS) system, and the complex relationship between film thickness, composition, and multi-scale structure was systematically investigated. A hallmark of this study is the observation of a significant structural transition facilitated by the PGS process; while the system establishes a high-quality c -axis-oriented template at the early growth stage, Bi-rich films exhibit a dramatic degradation in orientation ( F -value from 0.97 to 0.17) as thickness increases. This orientation loss is attributed to the stress relaxation-induced grain tilting inherent to the Bi-rich lattice. Remarkably, despite this pronounced structural deterioration, the thermoelectric properties—Seebeck coefficient, electrical conductivity, and power factor—remain nearly invariant across a broad thickness range (0.5 to 4.2 μm). This suggests that the electronic transport is predominantly governed by the stable initial layer formed under the high-energy particle flux of the PGS process, effectively decoupling functional performance from bulk structural changes. Optimization of the composition yielded maximum power factors of 21 μW/(cm‧K 2 ) for p -type ( x = 0.24) and 6.7 μW/(cm‧K 2 ) for n -type ( x = 0.73). These findings demonstrate that the PGS system provides a unique growth kinetic that ensures thickness-tolerant performance even under significant structural instability, offering a robust platform for scalable micro-thermoelectric devices.

Micrometer-scale chemical sensors serve as pivotal functional components that bridge microscopic environments and macroscopic information systems, yet integrating multiple sensing modalities within a single microscale fiber without compromising performance remains a challenge in materials design. Herein, we report a continuous wet-spinning process to fabricate multifunctional microfibers that integrate chemically responsive polyaniline (PANI) with high-Seebeck-coefficient tellurium nanowires (TeNWs). The optimized PANI/TeNWs composite fiber (60 wt.% TeNWs) achieves a Seebeck coefficient of 59.9 µV K-1 and a power factor of 9.2 µW m-1 K-2, enabling passive temperature monitoring with a detection limit of 1 K, where thermal gradients directly generate the sensing signal. Simultaneously, the fiber demonstrates remarkable chemical sensing capabilities, exhibiting a Nernstian pH response (59.25mV pH-1) and rapid ammonia detection (0.96 s at 50ppm). By demonstrating both passive thermoelectric transduction and active chemical sensing in a single microfiber platform, this work establishes a versatile material system that combines energy-autonomous temperature sensing with high-performance chemical detection. This integrated approach offers substantial application prospects in precision medicine and environmental safety monitoring, where miniaturized sensors with diverse functionalities are urgently needed.

A multifunctional kapok cellulose nanofiber/MWCNT/Fe3O4 flexible multilayer film for electromagnetic interference shielding.

High-throughput screening workflows often rank materials with a sequence of filters, but a single sequence can hide how strongly the final ranking depends on the chosen physical approximations. Here a multiscale cascade means an ordered workflow in which outputs from electronic, lattice, microstructural, uncertainty, and device-level models are passed from one layer to the next; the layers are theory or surrogate-model steps, not layers of LLMs. We use a large language model (LLM) as a workflow-design assistant to assemble candidate model stacks from the literature, after which the equations, code, and physical handoffs are inspected and implemented by the author. The test case is thermoelectric screening, where the dimensionless figure of merit ZT = S2σT/(κe + κL) combines the Seebeck coefficient S, electrical conductivity σ, electronic thermal conductivity κe, and lattice thermal conductivity κL. Two independently assembled eight-layer cascades are applied to the same 314-compound vacancy-containing chalcogenide library. LLM1 uses Fan-Migdal band gap renormalization, a Kubo-DMFT transport surrogate, and a literature-trained Gaussian process for κL. LLM2 replaces those three early layers with Bose-Einstein band gap renormalization, acoustic-phonon Boltzmann transport, and a Debye-Callaway integral. The common four-stage screen sends 15 compounds to full evaluation in each cascade: LLM1 selects tellurides headed by CuAlTe2 (ZTpeak = 8.61), whereas LLM2 selects nonoverlapping sulfides headed by CuPb2S4 (ZTpeak = 0.325). The absolute LLM1 values are not claimed as validated performance forecasts: CuAlTe2 is literature-supported as a promising bulk thermoelectric, but reported and expected values are closer to ZT ≲ 2 than to 8.6. This study underscores the importance of transparently comparing multiple workflow designs to understand the sensitivity and reliability of high-throughput screening outcomes in materials discovery.

The nontoxic β-FeSi2 semiconductor is gaining renewed interest as a thermoelectric material for waste heat recovery. Its earth-abundant elemental composition, consisting of iron (Fe) and silicon (Si), aligns well with the United Nations Sustainable Development Goals. However, the use of the β-FeSi2 semiconductor is limited by its high electrical resistivity. To improve the thermoelectric properties of the β-FeSi2 phase, specimens of FeSi2 were doped with Cu and Al and analyzed. X-ray diffraction and thermal analysis showed that small amounts (up to at least 2%) of Cu and Al dissolved into the FeSi2 phase. Cu doping reduced the electrical resistivity of FeSi2 but also lowered the Seebeck coefficient. In contrast, Al doping did not lower the Seebeck coefficient of FeSi2, while still reducing the electrical resistivity of FeSi2. Al doping thus improved the power factor of FeSi2 with 156 μW/mK2 and 314 μW/mK2 at room temperature for the 1% and 2% Al-doped specimens, respectively. Further thermal conductivity revealed that the Al-doped FeSi2 specimens showed lower thermal conductivity than the undoped FeSi2 specimen. Unlike in the case of the electrical resistivity, the 1% Al-doped specimen showed lower thermal conductivity than the 2% Al-doped specimen. The ZT of the 1% Al-doped specimen increased from 0.021 at room temperature to 0.052 at 600 K. This value was slightly higher than that of the Mn-doped β-FeSi2 but smaller than that of the Co-doped β-FeSi2.

Conductive polymer thermoelectric fibers, featuring inherent flexibility and weavability, hold great promise for wearable generation in smart clothing. However, balancing their thermoelectric and mechanical properties remains a critical challenge, restricting operational stability under mechanical deformation in wearable scenarios. Herein, we propose a novel wet-spinning strategy involving Ca2+-induced rapid gelation to fabricate high-performance PEDOT:PSS thermoelectric fibers. Ca2+-induced structural regulation optimized carrier transport, elevating the otherwise low Seebeck coefficient of PEDOT:PSS to 47.82 ± 1.04 μV·K-1 while retaining high electrical conductivity of 197.71 ± 7.83 S·cm-1. More importantly, Ca2+ can electrostatically anchor polymer chains, increasing cross-linking to form a tough network structure that improves both mechanical strength (140.37 ± 3.82 MPa) and fracture strain (29.14 ± 0.68%). The optimized fibers achieved synergistic thermoelectric-mechanical properties and a 0.05 K high temperature sensitivity. Integrated into smart gloves, these fibers enable temperature monitoring and heat-prevention warning, demonstrating significant potential for safeguarding the health and safety of disabled persons.

La3- xTe4 materials are ideal candidates for next-generation radioisotope thermoelectric generators due to their excellent thermoelectric performance and high-temperature stability. For decades, researchers have used substitutional doping or vacancy modulation to tune carrier concentration, but these methods can only tune it without optimizing the conduction band structure or suppressing lattice thermal conductivity. Interstitial doping strategy breaks this deadlock by enabling simultaneous electronic and thermal regulation without mutual interference. Herein, a series of Cu-doped La2.74CuxTe4 (x = 0, 0.01, 0.05, 0.1, 0.15) samples were synthesized. Cu incorporation elevates the Seebeck coefficient without degrading significantly the power factor, while simultaneously suppressing lattice thermal conductivity via anharmonic vibrational behavior that strengthens low-frequency acoustic phonon modes and intensifies phonon-phonon scattering. Among the synthesized compositions, La2.74Cu0.05Te4 achieves a peak thermoelectric figure of merit of 1.58 at 1073 K, representing a 34% improvement over the undoped La2.74Te4. Furthermore, the material exhibits a notable average zT value of 1.5 within the operational temperature range of 873-1073 K. When compared to the previously reported state-of-the-art lanthanum telluride-based thermoelectrics, this represents a significant improvement of 71.3% in the average zT value.

Two-dimensional Janus monolayers hold great promise for energy-related applications but are limited by inefficient charge separation, restricted optical absorption bandwidth and relatively high lattice thermal conductivity. One effective strategy to overcome these shortcomings is to construct van der Waals (vdW) heterostructures from distinct Janus monolayers. This study systematically performs first-principles calculations to investigate the dual-Janus HfSSe/SnSSe vdW heterostructure. The heterostructure is thermodynamically and dynamically stable, featuring a type-II band alignment with an indirect bandgap of 0.90 eV (HSE06) and 0.91 eV (HSE06 + SOC). Benefiting from intrinsic dipole synergy and efficient interlayer charge transfer with a tunneling probability (TB) of 27.05%, photogenerated carriers are spatially separated effectively. The heterostructure exhibits strong and broad-spectrum optical absorption, with a coefficient on the order of 105 cm-1 in the visible region and exceeding 3.0 × 105 cm-1 in the ultraviolet region. Thermoelectrically, it delivers a high Seebeck coefficient of 490 µV K-1 at 300 K and an ultralow lattice thermal conductivity of 0.31 W m-1 K-1 at 700 K, yielding a maximum thermoelectric figure of merit of 1.05 at 700 K, which outperforms the standalone Janus monolayers. The excellent optoelectronic and thermoelectric properties render the HfSSe/SnSSe heterostructure a promising multifunctional candidate for next-generation optoelectronic and thermoelectric devices, and establish a feasible design paradigm for Janus-based vdW heterostructures.

Developing scalable methods to mass produce macroscopic assemblies of 2D materials/nanosheets while retaining their nanofeatures is essential to translating their performance-enhancing 2D properties into macroscopic functionality. Here, we report a novel nanosheet processing technique to produce self-standing foils of NaxCoO2 nanosheets in a manner compatible with large-scale industrial manufacturing, such as roll-to-roll processing. In this approach, the nanosheets are chemically modified and coated onto a polymeric substrate using bidirectional shear force. Through a postheat treatment, the coated film is crystallized into the thermoelectric NaxCoO2 phase (0.63 < x < 0.71) while simultaneously burning away the polymer substrate, resulting in self-standing textured thin foils of thermoelectric NaxCoO2 nanosheets. Nanosheet foils up to 10 cm in lateral dimension and as thin as ∼10 μm are demonstrated. Seebeck coefficient and electrical conductivity values of the novel, shear-force-assisted coating-made foils are 64.6 μV. K-1 and 115.2 S.cm-1 at room temperature, respectively, resulting in significantly higher thermoelectric power factor compared to spin coating and blade coating fabricated foils, mainly owing to much higher electrical conductivity due to better nanosheet alignment and reduced porosity.

Signal cross-coupling in advanced electronic skin (E-skin) has severely limited its precision in simultaneous temperature, strain, and pressure sensing. Here, we report a flexible, self-powered multimodal sensor based on a heterostructure of redox ion-doped thermoelectric hydrogel and BaTiO3 (BTO) nanoparticle-modified polydimethylsiloxane (PDMS) films. This design achieves independent signal perception with exceptional cross-interference suppression (<4%). Systematic characterization reveals: Thermoelectric response: Seebeck coefficient of 1.05 mV·K-1 (R2 = 0.999) and negligible temperature-induced current deviation (3.32%). Mechanical sensing: Strain sensitivity of 0.91%-1 and pressure sensitivity of 9.76 mV·kPa-1 with an ultrafast response time (22 ms). Robustness: Performance decay of only 3.03% after 150 cyclic tests. Integrated into a finger-joint array, the sensor enables dynamic object surface temperature monitoring, piezoelectric information transmission, real-time sign-language gesture recognition, and intelligent discrimination of interpersonal interaction states. These advancements pave the way for high-precision human-machine interfaces, intelligent wearables, and health-monitoring applications.

The growing demand for environmentally safe and stable alternatives to lead-based halide perovskites has stimulated extensive research into lead-free double perovskites for energy applications. In this work, we present a comprehensive density functional theory (DFT) investigation of the structural, electronic, optical and thermoelectric properties of (Cs2/Rb2)LiGaCl6. Both compounds crystallize in a stable cubic phase with direct band gaps of 1.647 eV and 1.846 eV, respectively. These values lie close to the Shockley-Queisser limit, making them promising absorbers for solar energy conversion. Density of states and charge density analyses reveal a mixed ionic-covalent bonding character dominated by Ga-Cl interactions. Thermoelectric results show high Seebeck coefficients, favourable power factors and dimensionless figure of merit (ZT) values approaching unity. These findings confirm that these materials are good candidates for thermoelectric applications and indicate their potential for waste heat recovery. Optical properties demonstrate strong absorption across the UV spectrum, a pronounced dielectric response and significant optical conductivity arising from interband transitions. Overall, the findings highlight (Cs2/Rb2)LiGaCl6 as structurally robust, environmentally safe and multifunctional materials suitable for optoelectronic and thermoelectric energy technologies.

Side-chain engineering in metal coordination polymers (MCPs) remains largely underexplored. Our BTT-based strategy synergistically enhances Seebeck coefficient and photothermal efficiency while addressing the prevalent insolubility bottleneck.

Copper and zinc oxides (CuO, Cu2O, ZnO) are semiconductors with p-type and n-type conductivity, respectively, which have attracted attention as perspective materials for the research and development of p-n junction-based devices. Their low cost and abundance are ideal for applications in electronics and solar radiation sensing and harvesting. Most research involving these materials has been focused on UV-VIS photodetectors and solar cells, as well as p-n junction-based diodes. However, less attention has been paid to thermoelectric applications or the detection/energy harvesting of infrared radiation, which constitutes a significant part of the solar spectrum. In this work, electrical properties and the unbiased response to infrared radiation of CuO-Cu2O-ZnO heterojunction nanowires are studied. The vertically arranged CuO-Cu2O-ZnO nanowire arrays were synthesized directly on copper substrates using a combined thermal oxidation/thermal evaporation method and studied in-situ inside a scanning electron microscope using nanomanipulation techniques. The nanowires were found to exhibit diode-like behavior, indicating the presence of a p-n junction. Furthermore, a pronounced unbiased response to infrared radiation was observed and attributed to the photo-thermoelectrical effect. The estimated Seebeck coefficient, power factor, and responsivity of the CuO-Cu2O-ZnO heterojunction nanowires were 120 µV/K, 18 nW/mK2, and 150mA/W respectively. The absorbance capabilities of the material widen the potential for applications in effective harvesting of the full spectrum of solar energy. Additionally, the material furthers the development of nano-power generators operating at low-temperature differences of a few degrees Celsius, which may be favorable for a wide range of applications, like wearable electronics, Internet-of-Things, environmental and health sensors.

Two-dimensional (2D) materials have emerged as versatile platforms for exploring novel physical phenomena, particularly in electronic and thermoelectric transport, where reduced dimensionality enables confinement effects that provide enhanced control over fundamental properties. In this context, van der Waals heterostructures offer a strategic route to engineering these properties via proximity effects. In this work, we investigate Graphene (G)/Bi2Se3 heterostructures, experimentally accessible monolayers, by means of density functional theory (DFT) calculations, including spin-orbit coupling (SOC) and van der Waals corrections. Two stacking configurations, eclipsed and staggered arrangements, are considered, both with favorable interlayer binding energies that confirm the stability of the interface. Our results, globally similar for both configurations, show that the physical response is dominated by interfacial coupling, which induces significant charge transfer resulting from the competition between the work functions of the individual components and the formation of an interface dipole. This charge transfer results in a metallic character in the heterostructures with an upward Dirac cone shift. Furthermore, SOC and band hybridization increase the complexity of the electronic structure, leading to features such as band splittings and avoided crossings due to proximity interactions. These combined effects give rise to an enhancement of both electrical and electronic thermal conductivities; however, they reduce the Seebeck coefficient and the electronic figure of merit ZT(e), revealing a thermoelectric trade-off. Overall, we find that these heterostructures are better suited for efficient charge transport and heat dissipation than for thermoelectric energy conversion, underscoring how proximity effects can be exploited to tailor the functional limits of 2D systems.

The thermoelectric performance of GeTe is critically governed not only by the choice of dopant but also by the pathway through which it is introduced. Herein, we systematically compare three distinct Cu introduction routes in a Ge0.95Bi0.05Te matrix: direct Cu doping, BaCu2Te2 alloying, and BaCu2Te2 compositing. All three approaches effectively reduce the excessively high hole concentration, thereby decreasing electrical conductivity and increasing the Seebeck coefficient. However, they exhibit markedly different regulation mechanisms. Direct Cu doping achieves the most pronounced reduction in carrier concentration and optimizes carrier mobility but yields only a moderate improvement in the dimensionless thermoelectric figure of merit zT (∼1.86) due to limited phonon scattering. In contrast, the compositing strategy allows limited Cu diffusion into the matrix, while Ba induces additional Ge vacancies that partially compensate for the carrier reduction. The secondary phase introduces strong carrier scattering, suppressing carrier mobility, and also significantly enhances the density-of-states effective mass and reduces lattice thermal conductivity. Consequently, the Ge0.95Bi0.05Te + 2.0 wt % BaCu2Te2 composite attains a peak zT exceeding 2.0 at 623 K. BaCu2Te2 alloying exhibits intermediate behavior, with more Cu incorporation and stronger vacancy compensation, also achieving a zT near 2.0. This work demonstrates that the Cu introduction pathway dictates the balance between carrier concentration modulation, mobility preservation, effective mass enhancement, and phonon scattering, providing a paradigm for synergistically integrating doping and secondary-phase engineering in GeTe-based thermoelectrics.

Hydrogen is widely acknowledged as a highly effective potential solution to meet the steadily increasing demand for clean and environmentally friendly energy, where hydridosilicates emerge as an efficient hydrogen storage (HS) material. Therefore, BaSiH6 (BSH) is examined through first-principles calculations to assess its HS potential under strain. The calculated formation enthalpy (ΔHf) of -40.86 kJ per mol H2 for the unstrained (unstr.) system aligns excellently with the ideal value of -40 kJ per mol H2, while varying between -42 and -35 kJ per mol H2 under ±5% biaxial/hydrostatic strain. The calculated hydrogen desorption temperature (Tdes.) of 292 K (unstr. value) and strained values fall within the excellent range of 233-333 K. Besides, a gravimetric HS capacity of 3.53 wt% is achieved, and the volumetric HS capacity of 57.91 g H2 per L (unstr.) increases to 64.17 and 67.54 g H2 per L under -5% biaxial and hydrostatic strains, respectively. Moreover, ab initio molecular dynamics simulations confirm the thermal stability of the system at 300 K, as no spontaneous decomposition was observed. Additionally, all the structures are mechanically stable and exhibit ductile behavior. The ionic bonding in the structure is supported by electron density analysis, which reveals predominantly ionic Ba-H and covalent Si-H character. Interestingly, systems exhibit suitable energy gaps and substantial visible-light absorption, which enhances their potential for efficient solar energy conversion. Significant optical absorption is evident in the visible region, while the ultraviolet region shows high absorption coefficients of 154/149/142 × 104 cm-1 and 169/149/133 × 104 cm-1 across -5%/0%/+5% biaxial and hydrostatic strains, respectively. Interestingly, the system displays a high Seebeck coefficient and figure of merit of 0.68/0.69/0.76 and 0.69/0.69/0.74 at 800 K under the -5%/0%/+5% biax. and hydro. strain levels. Hence, the present study suggests the strong potential of BSH for HS, optoelectronic, and energy harvesting applications.

Human skin decouples concurrent thermal and mechanical stimuli, yet multimodal electronic textiles commonly suffer from signal crosstalk when temperature and pressure are read through a single channel. Here, we report a skin-inspired electronic textile built from a laminated nanoarchitecture assembled on knitted polyester by integrating silver nanowires (AgNWs) with MXene nanosheets and a protective polydimethylsiloxane (PDMS) overlayer. The resulting e-textile forms a mechanically compliant, percolated AgNWs/MXene nanonetwork that combines high breathability (469 mm·s-1), durability (>4000 cycles), and biocompatibility, while enabling strain, pressure, and temperature sensing in one platform. To resolve temperature-pressure crosstalk, a universal decoupling framework is established with two complementary routes: (i) neural-network-assisted qualitative discrimination of resistance signatures (accuracy >98.7%) and (ii) quantitative decoupling by leveraging a pressure-independent thermoelectric descriptor (Seebeck coefficient) together with the temperature coefficient of resistance to separate temperature-induced and pressure-induced resistance components. The decoupling approach could be applied to a variety of different sensors and is validated through gesture recognition and information transmission, making it a promising candidate for applications in healthcare monitoring, human-machine interfaces, and wearable electronics.

Bi2Te3 remains a benchmark n-type thermoelectric (TE) material for low-temperature energy conversion, but its small band gap can reduce efficiency because of thermally generated parasitic carriers. Elemental doping has been explored to improve TE performance, although systematic studies on manganese (Mn)-doped Bi2Te3 thin films remain limited. In this study, a radiofrequency magnetron co-sputtering workflow was used to fabricate Mn-doped Bi2Te3 thin films by varying Mn target power while maintaining constant Bi2Te3 deposition conditions. Structural, microstructural, compositional, and TE transport properties were evaluated using X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and temperature-dependent transport measurements. X-ray diffraction confirmed retention of the rhombohedral Bi2Te3 phase with a preferred (015) orientation, while peak shifts toward higher 2θ values were consistent with Mn-related lattice contraction. All films exhibited negative Seebeck coefficients, confirming n-type conduction. Increasing Mn doping enhanced the magnitude of the Seebeck coefficient but also increased electrical resistivity, demonstrating a transport tradeoff. The film deposited at 5 W Mn power achieved the highest power factor of 529.33 µW m-1 K-2 at 523 K because of its low resistivity combined with adequate thermopower. These results demonstrate that moderate Mn incorporation can improve the power-factor-related performance of Bi2Te3 thin films within the measured temperature range.

High-performance thermoelectric (TE) materials are crucial for efficient waste-heat recovery and solid-state cooling technologies. A persistent challenge in TE materials design arises from the strong interdependence among the electrical conductivity (σ), Seebeck coefficient (S), and lattice thermal conductivity (κL). Layered compounds can effectively suppress κL along the cross-plane direction owing to weak interlayer interactions; however, they often suffer from low carrier mobility (μ) caused by limited band dispersion and strong polar optical phonon (POP) scattering. Here, we perform high-throughput density functional theory calculations to screen 236 layered semiconductors and identify candidates with low effective mass (m*) and weak POP scattering. We identify 23 compounds with high cross-plane μ, among which 14 exhibit large power factors (S2σ). Notably, GaGe2Te stands out with exceptionally high cross-plane σ and power factor, enabled by a favorable combination of small m* and a small ionic dielectric constant. Simultaneously, GaGe2Te exhibits an ultralow cross-plane κL of 0.57 W m-1 K-1 at 300 K, originating from weak interlayer bonding and pronounced phonon anharmonicity. These results demonstrate an effective strategy to decouple electron and phonon transport in layered materials by mitigating POP scattering, thereby providing a promising pathway toward high-performance thermoelectric materials.