Search Results (346)

Lead-free halide double perovskites have emerged as promising candidates for sustainable optoelectronic and thermoelectric applications due to their tunable band gaps, high stability, and non-toxic nature. In this work, we systematically investigate the structural, electronic, optical, and thermoelectric properties of novel double perovskite compounds Rb₂InCuX₆ (X = F, Cl, Br) using density functional theory (DFT) combined with spin–orbit coupling (SOC). The structural stability of these materials is confirmed by evaluating the tolerance factor, octahedral factor, and negative formation energy. Accurate band structures obtained via the modified Becke–Johnson (mBJ) potential and SOC reveal direct band gaps of 1.49 eV, 0.91 eV, and 0.56 eV for Rb₂InCuX₆ (X = F, Cl, Br), indicating their suitability for solar cell applications. Optical properties, derived from the dielectric functions calculated within the Kramers–Kronig framework over a photon energy range up to 14 eV, show strong absorption peaks in the ultraviolet region, making these materials attractive for high-frequency optical conversion devices. Furthermore, thermoelectric parameters, including the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and power factor, are computed using the BoltzTraP code. Notably, the figure of merit (ZT) approaches 0.80 for Rb₂InCuF₆, close to the ideal value of unity, demonstrating excellent thermoelectric performance over a wide temperature range (200–800 K). Our findings establish Rb₂InCuX₆ (X = F, Cl, Br) as promising lead-free double perovskites for integrated optoelectronic and thermoelectric applications. Full article

Thermoelectric generator (TEG)-based energy harvesting (EH) has emerged as a promising solution for powering ultra-low-power electronic systems. However, the inherently low output voltage of miniature TEGs is often below a range of 40–100 mV under small temperature gradients, presenting a fundamental cold-start challenge for DC-DC boost converters, preventing fully autonomous operation without dedicated start-up circuitry. Although numerous start-up techniques have been reported, the existing literature lacks a focused, design-oriented review of circuit architecture specifically optimized for ultra-low-voltage TEG applications. This paper addresses this gap by introducing a unified classification framework and providing a structured, topology-oriented analysis of state-of-the-art start-up strategies for TEG-based EH systems. Reported techniques are organized into five categories: external energy assistance, mechanical switch-assisted techniques, multi-source EH, transformer-based architectures, and oscillator-driven DC-AC-DC conversion. Each category is comparatively evaluated in terms of start-up voltage, integration level, efficiency, and system autonomy. Among these, oscillator-based approaches, particularly ring oscillator (RO) architectures, emerge as the most viable pathway toward fully integrated and scalable implementations, owing to their CMOS compatibility and architectural flexibility. The review further discusses key design trade-offs, handover stability challenges, and practical limitations, and provides architectural insights to guide the development of next-generation autonomous TEG-powered platforms. Full article

Harnessing low-grade thermal energy from industrial processes and the environment represents an attractive route toward sustainable chemical production. In this work, we report a thermoelectrocatalytic (TE-Catal) system capable of converting small temperature gradients into chemical energy for hydrogen peroxide (H₂O₂) generation. A hybrid catalyst composed of nickel-based metal–organic frameworks (Ni-MOFs) nanoparticles integrated with carbon nanotubes (CNTs), Ni-MOFs/CNTs, was synthesized through a facile one-pot strategy. Under a temperature gradient, the thermoelectric response of the Ni-MOFs induces charge carrier generation through the Seebeck effect, enabling interfacial redox reactions that produce H₂O₂. However, rapid recombination of thermally generated carriers typically limits catalytic efficiency. By coupling Ni-MOFs with conductive CNTs networks, charge separation and transport are significantly enhanced due to the strong interfacial interaction and the high electrical conductivity of CNTs. As a result, the Ni-MOFs/CNTs nanohybrids exhibit greatly improved H₂O₂ generation rate of ~111.7 µmol g⁻¹ h⁻¹ compared with pristine Ni-MOFs (31.8 µmol g⁻¹ h⁻¹). Thermoelectric electrochemical measurements confirm that the CNT incorporation effectively promotes carrier migration and suppresses recombination. This study demonstrates the potential of MOF-based thermoelectric nanostructures for transforming waste heat into valuable chemical products. Full article

Nanotechnology has emerged as a key driver in radioisotope batteries, which offer unique advantages for long-term, maintenance-free energy supply in deep space exploration, medical implants, and nuclear waste utilization. This review summarizes recent progress in applying nanomaterials and nanostructures to overcome the limitations of nuclear batteries, including low energy conversion efficiency and poor stability. The main content focuses on the three primary conversion mechanisms of thermoelectric, radio-voltaic, and radio-photovoltaic batteries, discussing high-performance thermoelectric nanomaterials such as SiGe alloys, wide-bandgap semiconductors including diamond and SiC for enhanced carrier collection, and nanoscale radionuclide ources to mitigate self-absorption losses. This review further elaborates on how nanostructure regulation and interface engineering have significantly improved carrier collection efficiency and device stability. These advances have enabled notable civilian applications, such as the BV100 and “Zhulong No.1” nuclear batteries. Despite this progress, challenges remain in ensuring long-term material stability under extreme environments, maintaining performance consistency during macroscopic device integration, and addressing the high fabrication costs. The review concludes by outlining future research directions, including the development of novel nanomaterial systems, innovative nanostructure designs, scalable manufacturing processes, and enhanced device stability and safety, to further advance next-generation radioisotope batteries. Full article

A dedicated experimental setup was designed and constructed to investigate the performance of thermoelectric generators (TEGs) operating under cryogenic temperature conditions, representative of the heat recovery process during liquefied natural gas (LNG) regasification. The test bench enables precise control of both hot- and cold-side temperatures, simulating real operating conditions of mobile LNG systems. Six types of commercial TEG modules were tested at two hot-side temperatures (283 K and 340 K) and variable cold-side temperatures (150–260 K). The results showed that higher temperature differences significantly improved electrical power generation and conversion efficiency. For one of the TEGs, the electrical power and efficiency nearly doubled compared to the case with a hot-side temperature of 283 K. As the cold-side temperature increased, both performance indicators decreased almost linearly, as expected, with the lowest gradients observed for one of the TEGs, indicating the highest potential for total exergy recovery. These findings indicate that TEGs can effectively recover cryogenic heat during LNG vaporization. Scaling the system to practical applications shows that electric power exceeding 1 kW can be achieved in railway transport and up to 10 kW in marine applications, making this approach technically and economically viable for large-scale mobile LNG systems. Full article

Gallium-based liquid metals have garnered significant attention due to their distinct combination of metallic and liquid behavior at room temperature. This review systematically examines the fundamental properties and advanced multifunctional applications of this class of materials. Key characteristics such as low melting point, excellent fluidity, high electrical and thermal conductivity, and biocompatibility are first highlighted. Subsequently, progress in four major application areas is discussed. In sensing, these materials enable the fabrication of highly compliant and responsive devices capable of monitoring strain, temperature, and electromagnetic fields. Within biomedical engineering, their inherent low toxicity and biocompatibility underpin advances in biosensing platforms, precision drug delivery, and engineered tissue scaffolds. For energy-related applications, they are utilized in batteries and high-efficiency thermoelectric systems for converting heat into electricity. In catalysis, their dynamic and tunable interfaces facilitate efficient carbon dioxide conversion and selective thermocatalytic reactions. This review summarizes current advances in the application of gallium-based liquid metals and provides critical perspectives on future developments and opportunities in this technology. Full article

One of the main causes of failure in Insulated Gate Bipolar Transistor (IGBT) modules used in high-power conversion applications is thermal-stress-induced degradation. In this paper, an experimental testing setup for thermal stress and real-time degradation monitoring, as well as a deep neural network (DNN)-based lifetime prediction of IGBT modules under thermo-electrically stressed inverter operation, is proposed. A two-level SVPWM inverter is implemented to create a hybrid power cycling test platform that imposes well-defined junction-temperature swings representative of real-world operation by combining controlled electrical loading and active induction heating with water cooling. Throughout the aging process, on-state voltage and module temperature are constantly monitored to identify degradation precursors associated with thermo-mechanical fatigue. A physics-based Coffin–Manson lifetime model is fitted using failure datasets to characterize temperature-dependent lifetime behavior. An offline deep neural network (DNN) is trained on degradation trajectories derived from on-state collector–emitter voltage (V_ce,on) to predict remaining useful lifetime. This approach uses partial degradation histories for accurate early-life prediction. The proposed DNN model for competitive and computationally efficient lifetime prediction is validated experimentally on several IGBT modules under different thermal stresses, and its accuracy is compared with other prediction methods. Full article

With the intensification of the energy crisis and environmental issues, thermoelectric conversion technology has become a research focus due to its ability to directly convert thermal and electrical energy. β-Cu₂Se thermoelectric materials have garnered considerable attention owing to their distinctive physical and chemical characteristics. However, their practical implementation is hindered by the inherent imbalance between electrical and thermal transport properties. In this work, β-Cu₂Se/SnSe composite thermoelectric materials were successfully synthesized via a facile and scalable in situ compositing strategy by introducing SnSe micro-flakes as the secondary phase. The results demonstrate that the introduced SnSe secondary phase effectively modulates the carrier concentration and enhances the density-of-states effective mass through the energy filtering effect and resonant energy level regulation, thereby significantly optimizing the electrical transport properties. Meanwhile, the abundant heterointerfaces formed between the β-Cu₂Se matrix and introduced SnSe secondary phase induce intense phonon scattering, which efficiently suppresses the lattice thermal conductivity of the β-Cu₂Se/SnSe composites. Benefiting from the synergistic optimization of electrical and thermal transport behaviors, the β-Cu₂Se/5 mol% SnSe composite sample achieves a maximum figure of merit (ZT) value of ~0.51 at 750 K, which represents a 70% enhancement compared with the pristine β-Cu₂Se and a 60% improvement compared with the direct composite sample. This study provides a simple and effective in situ composite strategy for designing and synthesizing high-performance thermoelectric materials. Full article

Thermoelectric (TE) materials offer a promising route for direct thermal-to-electrical energy conversion via the Seebeck effect. Among them, GeTe exhibits superior performance in the mid-temperature range (500–800 K), whereas (Bi,Sb)₂Te₃ is widely regarded as the benchmark material for near low-temperature applications (< 450 K). To improve TE efficiency over a wider temperature range, segmented GeTe/(Bi,Sb)₂Te₃-based single-leg TE devices were developed. Specifically, based on nanocomposite technology, B₄C and SiC nanoparticles were, respectively, introduced into GeTe and (Bi,Sb)₂Te₃, achieving optimization of electrical conductivity alongside reduction in thermal conductivity, thereby enhancing the thermoelectric figure of merit (ZT). Finite element simulations were used to optimize the geometric structure of the segmented device, determining the ideal ratio of GeTe to (Bi,Sb)₂Te₃. The simulations predicted a maximum conversion efficiency (η_max) of 16.9% when the ratio of GeTe to (Bi,Sb)₂Te₃ was 0.24, with a power density of 18.5 mW/mm². Experimentally, the fabricated segmented device attained a peak conversion efficiency of 7.14% and a power density of 12.5 mW/mm² under a hot-side temperature of 773 K. These findings confirm that strategic segmentation, combined with nanoscale phonon scattering engineering, substantially improves overall TE device performance across broad temperature range, underscoring its potential for high-efficiency thermoelectric energy conversion systems. Full article

Conventional thermoelectric generators (TEGs) suffer from thermal resistance introduced by ceramic substrates and thermal interface materials, which limits the achievable temperature gradient across the junctions and reduces conversion efficiency. To overcome this limitation, a pin-fin integrated thermoelectric device (iTED) is proposed, in which the hot-side heat exchanger is incorporated directly into the hot-side interconnector, eliminating the ceramic and associated greases. An explicitly coupled thermal-fluid-electric finite-volume model is developed in ANSYS Fluent’s user-defined scalar (UDS) environment to quantify the simultaneous thermal-fluid-electric behavior of the iTED for inlet temperatures of 350 $\le T_{\mathrm{in}}\mathrm{K}\le$ 650, Reynolds numbers of 3000 $\le \mathrm{Re}\le$ 15,000, and load resistances ranging from 0.01 to ${10}^6$% of the internal device resistance ($R_{\mathrm{int}}$), for a fixed cold-side temperature of 300 K. The model is validated against established tube-bank correlations (2.2% agreement in pumping power) and a one-dimensional Explicit Thomson Model (1.2–6.9% agreement across all electrical system response quantities). Compared with an equivalently sized conventional TEG, the iTED achieves a 4.6-fold higher maximum power output (23.9 [W] vs. 5.2 [W] at Re = 15,000), a 2.8-fold higher thermal conversion efficiency (8.1% vs. 2.9%), and a 4.8-fold higher performance index (7.8 [-] vs. 1.6 [-] at Re = 3000), all at $T_{\mathrm{in}}$ = 650 K. A performance index analysis reveals that lower Reynolds numbers and higher inlet temperatures maximize the net power benefit, delineating the operational envelope in which the iTED produces more electrical power than is needed for fluid pumping. These findings demonstrate that device-level restructuring—specifically, the elimination of interfacial thermal resistance via integrated pin-fin heat exchangers—can yield performance improvements comparable to or exceeding those achievable through material advances alone. Full article

This study aims to develop high-performance hybrid nanocomposites for solid-state energy conversion. We achieved this by improving charge transport and thermoelectric efficiency through the interaction of polymers, nanoparticles, and ionic liquids. Nickel oxide nanoparticles (NiO NPs) were synthesized via a sonochemical route using a novel ionic liquid, 1,2-(propan). In our recent work, this approach enabled the formation of a hybrid [NiO NPs + IL] system, which was subsequently incorporated at different loadings (8, 15, and 30 wt.%) and coated with polyethylene glycol (PEG). The resulting nanocomposites were investigated to elucidate charge-transport mechanisms and assess the influence of the polymer coating on their optical, electrical, and thermal transport properties. Optical measurements showed a shift in the band gap due to π–π* electronic transitions. This effect indicates strong interface interactions. The PEG-coated [NiO NPs + IL] nanocomposites exhibited significantly enhanced charge-carrier mobility, resulting in improved electrical conductivity. Remarkably, a high Seebeck coefficient of 720 μV/K and an electrical conductivity of 0.35 S/cm were achieved, resulting in a maximum power factor of 24.74 μW/m·K², surpassing many recently reported polymer-based nanocomposites. PEG-coated [NiO NPs + IL] systems offer tunable optical properties and superior thermoelectric performance. Consequently, they are a promising alternative to conventional nanocomposites for sustainable energy conversion. Full article

Thermoelectric generators (TEGs) enable compact waste-heat energy harvesting but require high-gain DC–DC conversion due to their low-output voltage for DC microgrid interfacing. This work proposes a novel TEG-supplied two-stage architecture consisting of a perturb-and-observe (P&O)-based MPPT boost converter followed by a modified Z-source converter regulated through an advanced model predictive control (MPC) framework. The modified Z-source topology enables high-voltage gain without extreme duty ratios and mitigates switching losses by eliminating diode reverse-recovery effects via synchronous operation. To enhance dynamic performance, the advanced MPC strategy incorporating an adaptive ripple-based weighting mechanism is applied to the modified Z-source converter and benchmarked against MPC and sliding mode control (SMC). Simulation results under multiple disturbance scenarios, including hot-side and cold-side temperature variations, multi-condition disturbances, coupling-factor variation, and measurement noise, demonstrate that the proposed system maintains stable 400 V regulation at a 100 W output level. In contrast, MPC exhibits switching frequency deviations that increase switching losses during transient operation, while SMC suffers from significant voltage deviations under source variations. The proposed strategy maintains tight voltage regulation with nearly fixed-frequency operation around 50 kHz, providing a new perspective for TEG researchers while supporting sustainable waste-heat energy utilization. Full article

This study presents the design, implementation, and validation of a thermoelectric energy harvesting system that exploits waste heat from an industrial electric motor to power an autonomous wireless sensor device. The proposed prototype integrates a single thermoelectric generator directly onto the motor housing and leverages the built-in cooling fan to maintain a stable thermal gradient of approximately 4–5 °C. Under real factory conditions, the system harvested 6.17 J of energy over 9612 s, sustaining continuous operation and 41 successful Long Range (LoRa) data transmissions with a positive energy balance. Compared with related works, the prototype achieved competitive or superior performance while operating at a lower motor rating of 0.25 kW, highlighting its efficiency relative to system scale. Key innovations include a hybrid DC/DC conversion chain bridging ultra-low input voltages to modern microcontrollers, and an adaptive transmission strategy that ensures predictable energy management and reliable wireless communication. These results demonstrate the feasibility of battery-free sensing in industrial environments and underline the potential of thermoelectric harvesting as a cost-effective, maintenance-free, and environmentally responsible solution for predictive maintenance and Industry 4.0 applications. Full article

To boost the power and conversion efficiency of a polygonal automobile exhaust thermoelectric generator (AETEG), an innovative protrusion-type disturbance is introduced to the original sickle-shaped fins in this work. A coupled multiphysics field model integrating fluid, thermal, and electrical fields was constructed, a net power framework was formulated, and the protrusion structure parameters of protrusion radius and spacing were optimized. At a flow velocity of 40 m/s and an inlet temperature of 600 K, simulation results reveal that increasing the protrusion radius and protrusion spacing effectively improves the heat capture capability and the overall performance of the AETEG system. Simultaneously, the backpressure inside the heat exchanger increases, accompanied by a decline in temperature uniformity at the hot side of the thermoelectric modules (TEMs). Based on the designed multiple performance metrics, the optimal protrusion configuration is finally set as R = 8 mm, D_tg = 8 mm, and D_hf = 5.5 mm. Compared with the original AETEG system with sickle-shaped fins, the optimized protrusion design enhances the TEMs’ average hot-side temperatures by 5.11%, increases the output power by 42.22%, and improves the net power by 76.48%. Additionally, this optimization results in a 13.44% improvement in conversion efficiency and a 40.65% enhancement in net efficiency. Full article