In this work, we have proposed a data-driven screening framework combining the interpretable machine learning with high-throughput calculations to identify a series of metal oxides that exhibit both high-temperature tolerance and high power factors. Aiming at the problem of weak generalization ability of small data with power factors at high temperatures, we employ symbolic regression for feature creation which enhances the robustness of the model while preserving the physical meaning of features. 33 candidate metal oxides are finally targeted for high-temperature thermoelectric applications from a pool of 48,694 compounds in the Materials Project database. The Boltzmann transport theory is utilized to perform electrical transport properties calculations at 1,000 K. The relaxation time is approximated by employing constant electron-phonon coupling based on the deformation potential theory. Considering band degeneracy, the electron group velocity is obtained using the momentum matrix element method, yielding 28 materials with power factors greater than 50 μWcm−1K−2. The high-throughput framework we proposed is instrumental in the selection of metal oxides for high-temperature thermoelectric applications. Furthermore, our data-driven analysis and transport calculation suggest that metal oxides rich in elements such as cerium (Ce), tin (Sn), and lead (Pb) tend to exhibit high power factors at high temperatures.

Due to its wide band gap and low photogenerated carrier separation efficiency, TiO2 has an undesirable photocatalytic activity. In the present work, BiOCl was hydrothermally deposited on TiO2 and BiOCl/TiO2 composites with different ratios were obtained. The results show that 30 % BiOCl/TiO2 has the best performance of 1354.94 μmolg−1h−1, which is 18.4 times than pure TiO2 and 73.1 times than pure BiOCl. The significant increase in the photocatalytic efficiency of BiOCl/TiO2 composites is attributed to the reduction of their bandgap width and the fast separation of photogenerated electron-hole pairs. This work brings a new idea to increase the photocatalytic hydrogen production capability of TiO2.

Colloidal quantum dots (QDs), which consist of inorganic cores surrounded by soft organic ligands, can self-assemble into superlattices exhibiting long-range order. Their tunability, in terms of size, shape, and ligand properties, makes them promising for applications in solar cells, photodetectors, and light-emitting diodes. However, the complex interplay between ligand stiffness, QDs cores-ligands coupling strength, and its impact on QDs' morphology and thermal properties is not well understood. This work employs molecular dynamics simulations to investigate the possibility of modulating the thermal conductivity of QDs superlattices via ligand engineering. It is found that the structural stability of QDs superlattices depends significantly on the interaction strength between the QDs cores and ligands. At lower interaction strengths, the instability manifests itself in a random fusion of the QDs cores, while at intermediate strengths a stable simple cubic lattice structure is maintained. Conversely, higher interaction strengths lead to amorphization in the surface regions of QDs core. We observed a nonlinear trend in the thermal conductivity with varying QD-ligand interaction strengths due to competing factors: fusion of QDs cores at lower interaction strengths and increased crosslinking interaction among ligands at higher interaction strengths. The influence of ligand stiffness on thermal conductivity was found to be minimal. This study provides a deep insight into the role of ligand stiffness and interaction strength on structural dynamics and thermal transport in QDs superlattice and demonstrates the feasibility of engineering thermal transport in QDs superlattice via ligand engineering.

α-MgAgSb is a promising near-room temperature thermoelectric material, characterized by its intrinsically low lattice thermal conductivity, a feature attributed to the significant atomic mass contrast and complex crystal structure. In this work, we achieved respective zTavg values of 0.58 in the temperature range of 150-300 K and 1.22 in the range of 300-550 K for α-MgAgSb, indicating exceptional potential for both cooling and power generation applications. Additionally, through the reduction of cross-sectional size, the stability of MgAgSb/Ag interface was enhanced under high temperature, which is crucial for the practical application of thermoelectric module. To verify the property of α-MgAgSb material, a 7-pair MgAgSb/Bi2Te3 module was fabricated, demonstrating a maximum cooling temperature difference ΔTmax of 60 K at hot-side temperature of 300 K and a power generation efficiency ηmax of 7.2% with ΔT of 275 K. This work paves the way for the application of Mg-based thermoelectric materials.

The controlling of heat flow direction stands as a prominent methodological approach within the domain of thermal management, and this can be accomplished through the utilization of thermal diodes. However, if the thermal diode lacks mechanical compliance, hindering its intimate contact with heat source/sink surfaces, the thermal rectification performance is limited. In this work, we propose a method to solve the mechanical compliance problem that is introducing phase change material (PCM) consisting of dual alkanes (hexadecane and paraffine wax) and polyurethane to fabricate the heterojunction thermal diode. The fabricated thermal diode exhibits an ultra-soft mechanical feature, with a low elastic modulus of 0.4 KPa and >300 % elongation until failure – the best values reported to date for thermal diodes. The measured thermal rectification factor is as high as 1.42 – in line with the theoretical model prediction. Molecular dynamic simulations reveal that the thermal rectification mechanism of the PCM-based thermal diode originates from the crystal-amorphous phase transition of the hexadecane terminal as the temperature bias flips. Therefore, the heat flow in the forward direction is greater than the flux in the reverse direction. A series of experiments and finite element analyses are employed to verify the feasibility of thermal diodes for applications in real contexts like the civil engineering.

Nowadays, perovskite solar cells (PSCs) have gained significant attention as one of the most promising new energy technologies. However, the application of spiro-OMeTAD, a highly efficient organic hole transport material (HTM) in PSCs, is limited due to its inherent weaknesses in conductivity and hole mobility. Here, a free radical initiator, tert-butyl peroxy-2-ethylhexanoate (TBPEH) is introduced to induce the rapid and controllable oxidation of Spiro. TBPEH-modified hole transport layer (HTL) produces more free radical cations, increasing carrier mobility and electrical conductivity. A smoother surface of the modified HTL improves the charge transport efficiency. Additionally, trap-state density and defect-induced nonradiative recombination of TBPEH-modified device are decreased. In addition, better energy level matching between the HTL and perovskite layer enables more efficient hole transport. Consequently, the PSC doped with TBPEH achieves a champion power conversion efficiency (PCE) of 24.33%, surpassing the PCE of 21.72% obtained from the pristine device. Furthermore, the TBPEH-modified devices show better stability. Storing in the atmosphere at 30% relative humidity for 42 days, the TBPEH-modified device maintains 90.8% of its highest efficiency, compared to the 73.8% of the pristine one.

Energy harvesting is essential for the internet-of-things networks where a tremendous number of sensors require power. Thermoelectric generators (TEGs), especially those based on silicon (Si), are a promising source of clean and sustainable energy for these sensors. Although large thermoelectric figure of merit has been reported for nanostructured Si material, however, nanostructuring has not been effectively used in device applications, and the reported performance of hybrid planar-type Si TEGs never exceeded normalized powers of due to the poor thermoelectric performance of Si and the suboptimal design of the devices. Here, we report a hybrid planar-type Si TEG with a normalized power of around room temperature. The increase in thermoelectric performance of Si by nanostructuring based on the phonon-glass electron-crystal concept and optimized three-dimensional heat-guiding structures resulted in a record-high power density. The improvement of power generation by a factor of 10 makes the once-a-day sensing applications realistic in a practical environment for the first time. In-field testing demonstrated that our Si TEG functions as a sufficient energy harvester. This demonstration paves the way for energy harvesting with a low-environmental load and cost-effective material with high throughput, a necessary condition for energy-autonomous sensor nodes for the trillion sensors universe.

Realizing glass-like ultralow lattice thermal conductivity κL in an ordered crystalline material is overwhelmingly appealing for various applications in thermoelectrics and thermal barrier coatings. Here, based on first-principles calculations, we take CuPbBiS3 as an example and systematically study the underlying physical mechanism of the ultralow and glass-like κL in aikinite. It is found that the strong anharmonic renormalization induces temperature-driven stiffening of the acoustic modes and low-lying optical modes from Pb, Cu, and Bi atoms, while leading to the softening of high-frequency optical phonon modes from S atoms. Further analyses highlight that CuPbBiS3 hosts metavalent bonding, stereochemical lone pair activity, and loosely bonded rattling atoms. These characteristics arouse partially liquid-like state, synergistically contribute to strong anharmonicity, and result in unexpectedly low thermal conductivity. Finally, our calculated κL at 300 K is 0.68 Wm−1K−1 with a non-standard dependency of κL ∝ T−0.7, which reasonably agrees well with experimental values in both magnitude (0.52 ± 0.05 Wm−1K−1 at 300 K) and temperature-dependence trend (∝ T−0.2). We demonstrate that the anomalous thermal transport originates from the dual particle-wave behavior of the heat-carrying phonons, in which wavelike tunneling contribute over 18% to the total κL when T exceeds 300 K. Our work underpins the microscopic origins of ultralow κL in CuPbBiS3, providing crucial insights into designing highly efficient aikinite materials for thermoelectric conversion.