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Plasmonic coupling among nanocavities creates a significant collective response of near-field enhancement, leading to numerous applications such as extraordinary optical transmittance, enhanced spectroscopy, energy harvesting, photo-enhanced catalysis, meta-lens, etc. We report here a perturbation theory based on the two-body interaction potential to clarify the plasmonic coupling between/among nanocavities. With this theory, we demonstrated that one can calculate the near-field distribution of a cluster of nanocavities and that the results are in agreement with simulations by the finite element method and those measured by a scanning near-field optical microscope. The perturbation theory offers an effective way in dealing with the plasmonic coupling behavior of nanocavities. [ABSTRACT FROM AUTHOR]

The dynamic response and damage fracture of brittle materials under explosive cutting have always been important research issues in the fields of military, aerospace, and other engineering fields. In this paper, a linear shaped charge cutting model for explosive cutting of brittle materials is proposed. This model suggests that explosive cutting is caused by the combined effects of jet penetration, spallation, and impact fracture. Theoretical calculation models for jet penetration, spallation, and impact fracture were constructed, and the concept of impact strength was introduced to establish dynamic mechanical performance parameters for brittle materials. A calculation program for explosive cutting of brittle materials was developed using the Python language, which can calculate the jet penetration depth, spallation thickness, and impact fracture thickness by inputting parameters such as the size and mechanical properties of the linear shaped charge and target plate, and determine whether the target plate can be successfully cut. Subsequently, a series of explosion cutting experiments and numerical simulations for brittle target plates were conducted to verify the accuracy of the calculation program. The results indicate a high degree of consistency between simulation, experimentation, and program calculation results. This work can provide guidance and promotion for the design and application of explosive energy harvesting cutters. [ABSTRACT FROM AUTHOR]

Thermophotovoltaic (TPV) systems can be used to harvest thermal energy for thermoelectric conversion with much improved efficiency and power density compared with traditional photovoltaic systems. As the key component, selective emitters (SEs) can re-emit tailored thermal radiation for better matching with the absorption band of TPV cells. However, current designs of the SEs heavily rely on empirical design templates, particularly the metal-insulator-metal (MIM) structure, and lack of considering the overall performance of TPV systems and optimization efficiency. Here, we utilized a deep reinforcement learning (DRL) method to perform a comprehensive design of a 2D square-pattern metamaterial SE, with simultaneous optimization of material selections and structural parameters. In the DRL method, only the database of refractory materials with gradient refraction indexes needs to be prepared in advance, and the whole design roadmap will automatically output the SE with optimal Figure-of-Merit (FoM) efficiently. The optimal SE is composed of a novel material combination of TiO2, Si, and W substrate, with its thickness and structure precisely optimized. Its emissivity spectra match well with the external quantum efficiency curve of the GaSb cell. Consequently, the overall performance of TPV is significantly enhanced with an output power density of 5.78 W/cm2, an energy conversion efficiency of 38.26%, and a corresponding FoM of 2.21, surpassing most existing designs. The underlying physics of optimal SE is explained by the coupling effect of multiple resonance modes. This work advances the practical application potential of TPV systems and paves the way for addressing other multi-physics optimization problems and metamaterial designs. [ABSTRACT FROM AUTHOR]

In the current study, complementary metasurface units with toroidal geometry were fabricated, using the computer numerical control engraving method. The metasurfaces were engraved in copper-coated, FR-4 plates. The produced metasurfaces were electromagnetically characterized in the microwave regime. Furthermore, they were studied regarding their energy harvesting capability, in the microwave range, where they absorb electromagnetic energy. It was found that toroidal structures harvest energy from the incident microwaves and transform it to electric power, through a simple rectification circuit. Moreover, their energy harvesting efficiency was found to be comparable or even superior to those of others reported so far. Therefore, the hereby obtained experimental results evidently show that engraved toroidal metasurfaces could potentially be used as energy harvesters in the microwave regime. [ABSTRACT FROM AUTHOR]

Within the field of elastic metamaterials, topological metamaterials have recently received much attention due to their ability to host topologically robust edge states. Introducing local resonators to these metamaterials also opens the door for many applications such as energy harvesting and reconfigurable metamaterials. However, the interactions between phenomena from local resonance and modulation patterning are currently unknown. This work fills that gap by studying multiple cases of spatially modulated metamaterials with local resonators to reveal the mechanisms behind bandgap formation. Their dispersion relations are determined analytically for infinite chains and validated numerically using eigenvalue analysis. The inverse method is used to determine the imaginary wavenumber components from which each bandgap is characterized by its formation mechanism. The topological nature of the bandgaps is also explored through calculating the Chern number and integrated density of states. The band structures are obtained for various sources of modulation as well as multiple resonator parameters to illustrate how both local resonance and modulation patterning interact together to influence the band structure. Other unique features of these metamaterials are further demonstrated through the mode shapes obtained using the eigenvectors. The results reveal a complex band structure that is highly tunable, and the observations given here can be used to guide designers in choosing resonator parameters and patterning to fit a variety of applications. [ABSTRACT FROM AUTHOR]

Over 2300 years ago, the discovery of tourmaline led to the understanding of pyroelectric properties, which opened new doors to various applications of pyroelectric crystal, such as neutron and x-ray generation, energy harvesting, mass spectrometry, high-voltage sources, and more. In the last two decades, researchers have carried out extensive research and development to select components and materials and innovate the design and construction of the pyroelectric neutron generator (PNG). This manuscript investigates the process and history of the PNG's development. It explains the physics governing pyroelectric crystals and the method of producing neutrons in a comprehensive and straightforward manner. Although PNGs have a lower yield and shorter lifetime compared to other neutron generators, they are still significant for research purposes due to their lack of need for an external high-voltage power supply, lower cost, smaller size, and safety. The main objective of this manuscript is to bring more attention to the research and development of PNGs. In recent years, new methods have been introduced that reduce the amount of neutron flux required for various applications. This has raised hope for the progress of commercial and industrial use of PNGs in the near future. The manuscript mentions some research cases that represent the future perspective of PNG development. Furthermore, the challenges faced by PNGs can be handled more efficiently with the utilization of generative learning algorithms and improvements in the components/mechanisms used for PNG design. [ABSTRACT FROM AUTHOR]

Environmental effects in excitation energy transfer have mostly been modeled by baths of harmonic oscillators, but to what extent such modeling provides a reliable description of actual interactions between molecular systems and environments remains an open issue. We address this issue by investigating fluctuations in the excitation energies of the light harvesting 2 complex using a realistic all-atomistic simulation of the potential energy surface. Our analyses reveal that molecular motions exhibit significant anharmonic features, even for underdamped intramolecular vibrations. In particular, we find that the anharmonicity contributes to the broadening of spectral densities and substantial overlaps between neighboring peaks, which complicates the meaning of mode frequencies constituting a bath model. Thus, we develop a strategy to construct a minimally underdamped harmonic bath that has a clear connection to all-atomistic dynamics by utilizing actual normal modes of molecules but optimizing their frequencies such that the resulting bath model can best reproduce the all-atomistic simulation results. By subtracting the underdamped contribution from the entire fluctuations, we also show that identifying a residual spectral density representing all other contributions with overdamped behavior is possible. We find that this can be fitted well with a well-established analytic form of a spectral density function or, alternatively, modeled as explicit time dependent fluctuations with muti-exponential or power law type correlation functions. We provide an assessment and the implications of these possibilities. The approach presented here can also serve as a general strategy to construct a simplified bath model that can effectively represent the underlying all-atomistic bath dynamics. [ABSTRACT FROM AUTHOR]

This paper explores the emergence of topological interface states in one-dimensional locally resonant lattices incorporating inerters in both nearest neighbor (NN) and beyond-nearest neighbor (BNN) coupling. The investigation focuses on the unique wave propagation characteristics of these lattices, particularly the presence and behavior of interface states. The non-trivial topological behavior due to broken inversion symmetry within the unit cell of the locally resonant lattice is comprehensively investigated in the presence of inerters in NN and BNN coupling. The emerging interface states in the supercell analysis exhibit specific spatial and frequency localization properties due to inerter-based BNN interactions. Additionally, the study demonstrates the ability of inerter elements with weak inertance to control the frequency of interface states while maintaining the fundamental topological properties of the lattice. The identified topological interface states in lattices with BNN coupling present an opportunity for designing diverse devices, such as waveguides, filters, sensors, and energy harvesting systems. Overall, this research enhances our comprehension of topological phenomena in inerter-based locally resonant lattices with BNN interactions and introduces possibilities for creating robust and versatile devices based on topologically protected edge/interface states. [ABSTRACT FROM AUTHOR]

In this paper, a wideband metasurface-loaded (MTS-L) rectenna system is proposed to capture electromagnetic (EM) energy at arbitrary azimuth angles. The radiation patterns of different modes in the original MTS configuration are analyzed using the characteristic mode theory, and potential modes with omnidirectional radiation are screened out. By the arrangement of patches, the roundness performance of the radiation pattern can be ameliorated, and the omnidirectional characteristic is obtained over a wide frequency band. Subsequently, the surface current density of the selected mode is carefully and artificially designed to facilitate probe excitation as well as refrain from introducing complex power-combining networks. A wideband rectifier circuit is designed as the load of the proposed antenna. Eventually, measured results show that it operates from 4.6 to 9.6 GHz with a fractional bandwidth of 70.4%, and the peak system efficiency is 52.2%. The proposed system demonstrates excellent potential for wireless power transmission and EM energy harvesting in indoor environments. [ABSTRACT FROM AUTHOR]

The rapid development of wearable electronics highlights the urgence to develop the portable energy harvester with excellent output performance, comfortability, and sustainability. This work designs an electromagnetic walking energy harvester based on water turbine that can be embedded in shoes with good comfortability. Its working principle is that the walking generated pressure energy drives a miniature hydraulic turbine to output electricity. Experimental results show that an average power of 300 and 180 mW can be produced at heel and toe, respectively, when a man of 80 kg walks at a speed of 1.8 m s−1. This power output exceeds the piezoelectric, triboelectric, and electromagnetic walking energy harvesters reported in the past. Additionally, the simpler structure endows it better comfortability as compared with the electrostatic capacitances. Computational fluid dynamics simulations provide a further insight that the efficiency of turbine can reach 13.5% by optimizing parameters of blade number and outlet flow ratio. Finally, user real-time positioning and trajectory recording are successfully demonstrated via a wearable GPS means Global Positioning System module powered by the harvester. Due to the combination of high output performance, simple structure and low discomfort, the water turbine based walking energy harvester will provide a wide application potential in wearable devices. [ABSTRACT FROM AUTHOR]

Electric-field energy harvesters (EFEHs) have emerged as a promising technology for harnessing the electric field surrounding energized environments. Current research indicates that EFEHs are closely associated with Tribo-Electric Nano-Generators (TENGs). However, the performance of TENGs in energized environments remains unclear. This work aims to evaluate the performance of TENGs in electric-field energy harvesting applications. For this purpose, TENGs of different sizes, operating in single-electrode mode were conceptualized, assembled, and experimentally tested. Each TENG was mounted on a 1.5 HP single-phase induction motor, operating at nominal parameters of 8 A, 230 V, and 50 Hz. In addition, the contact layer was mounted on a linear motor to control kinematic stimuli. The TENGs successfully induced electric fields and provided satisfactory performance to collect electrostatic charges in fairly variable electric fields. Experimental findings disclosed an approximate increase in energy collection ranging from 1.51% to 10.49% when utilizing TENGs compared to simple EFEHs. The observed correlation between power density and electric field highlights TENGs as a more efficient energy source in electrified environments compared to EFEHs, thereby contributing to the ongoing research objectives of the authors.

Energy harvesting textiles have emerged as a promising solution to sustainably power wearable electronics. Textile-based solar cells (SCs) interconnected with on-body electronics have emerged to meet such needs. These technologies are lightweight, flexible, and easy to transport while leveraging the abundant natural sunlight in an eco-friendly way. In this Review, we comprehensively explore the working mechanisms, diverse types, and advanced fabrication strategies of photovoltaic textiles. Furthermore, we provide a detailed analysis of the recent progress made in various types of photovoltaic textiles, emphasizing their electrochemical performance. The focal point of this review centers on smart photovoltaic textiles for wearable electronic applications. Finally, we offer insights and perspectives on potential solutions to overcome the existing limitations of textile-based photovoltaics to promote their industrial commercialization.

Summary: Relay selection plays a crucial role in enhancing the performance of wireless networks particularly in the context of cognitive radio (CR) systems with energy harvesters. In this paper, we propose a novel approach, namely, CGAPSO Shapley, for the best relay selection while simultaneously optimizing the parameters of signal‐to‐interference‐plus‐noise ratio (SINR), throughput, and outage probability. The CGAPSO Shapley algorithm combines the Shapley value, a cooperative game theory concept, with cellular genetic algorithm particle swarm optimization (CGAPSO) to achieve effective and efficient optimization of relay selection. The CGAPSO framework provides a hybrid structure that integrates cellular genetic algorithm (CGA) and particle swarm optimization (PSO), enabling simultaneous evolution of the population and particles within cells. The incorporation of the Shapley value and the hybrid CGAPSO framework enables effective exploration of the solution space and provides decision‐makers with comprehensive insights for relay selection. By utilizing the Shapley value, we assign weights to the relay nodes based on their contributions to the overall optimization objectives, considering their CR capabilities and energy harvesting capabilities. Some benchmark test functions are used to compare the hybrid algorithm with both the standard CGAPSO, Particle swarm optimization gravitational search algorithm (PSOGSA) and PSO algorithms in evolving best solution. The results show the hybrid algorithm possesses a better capability to escape from local optimums with faster convergence than the standard algorithms. The novel CGAPSO Shapley approach achieves an outage probability of 0.323324, marking a significant improvement of 60% over the outage probability achieved with conventional approach. [ABSTRACT FROM AUTHOR]

There is always considerable inconsistency between the input energy and the amount of the energy required for the load in piezoelectric transducers (PZTs) energy harvesting interface circuits that often degrades the harvesting performance of most of them. Multiple piezoelectric transducers (multi‐PZTs) vibration scavenging may address this issue by enhancing input power and, consequently, environmental adaptability and reliability. The proposed interface circuit may extract energy from a PZT array regardless of each PZT amplitude, frequency, or phase, even under dynamic or heavy load circumstances. The circuit is thoroughly simulated by LTSpice software and evaluated by post‐simulation calculations and discussions. The simulation findings demonstrate that the proposed self‐powered (SP) SECE‐based multi‐PZT EH interface circuit, named MI‐SP‐SECE, can extract a peak power of 12.8 µW from three PZTs in the provided actual scenario at a dynamic load regime with a simulated excitation of 1.5 g and 50 Hz. The proposed circuit's energy integration and harvesting efficiencies are 75% and 85%, respectively. It can achieve a power enhancement of 2.8× relative to a multi‐input full‐bridge rectifier. In addition, the proposed circuit is scalable effectively because it requires just one inductor component. [ABSTRACT FROM AUTHOR]

Studies of metal-free carbon nanostructures prove effective in energy and environmental applications due to their molecular tunability and vast chemical space. Herein, we synthesize nitrogen-containing multi-walled carbon nanotubes (N-MWCNTs) via. acid-catalysed incorporation of 3, 4-diaminopyridine into multi-walled carbon nanotubes (MWCNTs), and demonstrating their efficacy in electrocatalytic hydrogen evolution reaction (HER) and semicarbazide (SCB) oxidation for energy and environmental waste management, respectively. Successful synthesis is further confirmed by analysis techniques, i.e. Fourier transform infrared (FTIR) spectral analysis shows the diminishing OH frequency around 3250 cm−1 in MWCNTs after functionalization and the formation of an O C–NH bond in N-MWCNTs at 1710 cm−1. X-ray diffraction (XRD) confirms the incorporation of N-species, while Raman spectroscopic analysis indicates an increase in the I D /I G ratio MWCNTs (∼1) to N-MWCNTs (∼1.25), suggesting more defective sites in the N-MWCNTs nanocomposite. X-ray photoelectron spectroscopy (XPS) reveals peaks at 399.38, 400.49, and 402.05 eV, attributed to pyridinic-N, aromatic amide-N, and protonated amine groups, respectively. N₂ adsorption-desorption studies shows a high Brunauer-Emmett-Teller (BET) surface area for N-MWCNTs (119.22 m2/g) compared to MWCNTs (74.94 m2/g). Linear sweep voltammetry (LSV) profiles demonstrate enhanced activity of N-MWCNTs for both HER and SCB oxidation at an ultralow potential of E = −0.55 V vs RHE at 10 mA/cm2, with a lower Tafel slope of 108 mV.dec−1. Moreover, the electrochemical sensing studies indicates on N-MWCNTs were demonstrating an efficient electron transfer to SCB with the lower detection limit of 0.004 μmol. This work provides carbon-based metal-free electrocatalysts for energy harvesting and environmental management. [Display omitted] • An easy way to synthesize N-MWCNTs nanocomposites was developed. • N-MWCNTs shows superior electrochemical activity and stability in semicarbazide and hydrogen evolution reactions than MWCNTs. • The presence of N in N-MWCNTs develops new sites for enhancing conductivity and electrochemical reactivity. [ABSTRACT FROM AUTHOR]

In the present work, flexible Potassium Sodium Niobate - Polyvinyledene Fluoride (KNN-PVDF) composite sheets have been developed and utilized for the realization of a highly efficient pyroelectric energy harvester. KNN-PVDF composite sheets with varying the weight % of KNN (10–50 %) have been synthesized using solution casting method. The influence of KNN (Potassium Sodium Niobate) on the structural, morphological, and dielectric properties of PVDF has been investigated. The highest value of pyroelectric coefficient of 14.7 x 10 −4 Cm −2K−1 has been obtained for the flexible sheets of 30 % KNN-PVDF composite with change in temperature. It has been also observed from the ferroelectric studies that a high value of saturation polarization of 1.44 μC/cm2 is obtained at the applied bias of 5 V and 50 Hz frequency due to the presence of 30 % KNN in the KNN-PVDF composite sheets. The obtained results show the potential application of non-toxic, lead free KNN-PVDF composite sheets for thermal energy harvesting applications utilizing pyroelectric effect. [ABSTRACT FROM AUTHOR]

The global focus on electromagnetic interference and pollution is undeniable. To counter these challenges, high-performance microwave-absorbing materials (MAMs), typically composed of dielectric and magnetic components, offer effective solutions by ensuring favorable impedance matching. Leveraging these MAMs has proven beneficial across various sectors, including 5G technology, information security, energy harvesting, diminished radar cross-section, and advancements in military applications. We successfully synthesized composites of La 1.5 Sr 0.5 NiO 4 (LSNO) and SrFe 12 O 19 (SrM) composites through ball milling and heat treatment. With the escalation of SrM weight percentage in the composites, noticeable alteration in structural, morphological, and static magnetic characteristics was ensured. Moreover, the amalgamation of these components bolstered the EM properties, consequently yielding exceptional microwave absorption capabilities in the composites. The composites with 40, 60, and 80 wt% of SrM (named S4, S6, and S8) exhibited excellent microwave absorption performance with an absorption rate of over 99.9 % for a thin thickness. The S4 and S8 composites attained reflection loss (RL) values of −34.75 dB and −36.93 dB, with 2.0 and 1.6 mm thicknesses, respectively. Meanwhile, the S6 composite achieved an RL value of −44.24 dB with a thickness of 1.9 mm. These composites' outstanding microwave absorption performance can be attributed to their significant magnetic loss, remarkable dielectric loss, and synergistic effects. [ABSTRACT FROM AUTHOR]

This paper introduces a broadband electromagnetic wave absorber with characteristics of polarization-independence and wide-angle stability based on resistive films with a three-dimensional (3D) configuration. The absorber consists of a 3D dielectric substrate array covered by a resistive film, which not only broadens the operation frequency band but also improves the absorption with large incidence angles. Simulated results indicate that the absorber achieves wideband absorption with over 90% absorptivity in the frequency range of 5.7–41.8 GHz, corresponding to a relative absorption bandwidth of 152%. Due to the high symmetry of the structure, the absorber is insensitive to polarization angles. Moreover, the presented design maintains wave absorption greater than 90% when incidence angle reaches 70∘ due to its 3D structure that ensures high absorption for wide incidence angles. The mechanism of this structure is investigated through surface current and power consumption distribution, while optimization parameters are analyzed for achieving the desired bandwidth. This absorber has the advantages of wide-band absorption and excellent stability under oblique incidence angles, making it potentially useful in applications such as electromagnetic shielding and energy harvesting. [ABSTRACT FROM AUTHOR]

In response to the low operating speed and poor stability of energy harvesting systems in smart grids, an energy harvesting optimization method based on improved convolutional neural networks and digital twin technology is proposed in the experiment. Firstly, a smart grid data transmission framework integrating digital twin technology is proposed. A digital twin mapping method based on time, data, and topology structure is used to realize the digital twin mapping at the device level of power grid. Through data synchronization and interaction between the physical power grid and the digital twin model, the operational efficiency and reliability of the power grid are improved. Then, the classical convolutional neural network and attention mechanism are used to comprehensively analyze the physical topology data in the smart grid energy acquisition system. The improved lightweight target detection model is combined to monitor the equipment status of the smart grid and extract key features. Simultaneously utilizing convolutional attention mechanism to dynamically adjust the feature weights of channels or spaces, completing the preprocessing of energy harvesting data. Finally, combined with energy harvesting and power grid switching system, the process of energy harvesting and power grid operation are optimized together. On the training and validation sets, when the channels exceeded 60, the proposed method achieved a system energy efficiency of 55% during operation. The system energy efficiency of the other three comparative algorithms was all less than 40%. In practical applications, as the energy transfer loss increased to 1.0, the system throughput increased to 50 bits. The electricity needs of different users were met, and the difference between power allocation and optimal power allocation was small, which was very reasonable. This proves that the research has effectively optimized the energy harvesting system in the smart grid, improving the efficiency and reliability of the system in practical applications of the smart grid. At the same time, in the increasingly severe energy problem, this system can further provide technical references for the utilization of renewable energy and help achieve the goal of sustainable energy. [ABSTRACT FROM AUTHOR]

In this study, a piezoelectric nanogenerator (PENG) based on multilayer composite fiber had good and stable piezoelectric output performance, which could realize biomechanical energy collection and human movement monitoring. The polyvinylidene fluoride‐hexafluoryl propylene (P(VDF‐HFP)) composite fiber doped with MXene was used as a promising piezoelectric functional layer (MPFP). By electrospinning, P(VDF‐HFP) composite fiber was constructed by alternating electrospinning with polyurethane (TPU) nanofibers layer by layer. The adoption of MXene as a functional filler promoted the transformation of P(VDF‐HFP) from α to piezoelectric β‐crystal, the piezoelectric β‐crystal content of P(VDF‐HFP) increased, and the dielectric properties and polarization levels were enhanced. At the same time, the multi‐layer structure design improved the piezoelectric sensitivity and mechanical properties of the composite fiber, and the composite fiber was more flexible and had longer tensile strain. With excellent dielectric and mechanical properties, 3MPFP/TPU/3MPFP/TPU multilayer composite fibers showed piezoelectric sensitivity of 10.88 V/kPa. Under the action of palm pressing, the PENG generated an open circuit voltage of 25 V, and the voltage signal of the device under different motion forms had specific characteristics such as peak value, frequency, and shape, which could be used to realize the analysis of human motion forms. This study provided an efficient, simple, and creative new idea for the application of flexible energy storage electronic devices, PENGs, and piezoelectric sensors. [ABSTRACT FROM AUTHOR]

Polymer-based ferroelectric composites, particularly those containing Poly (vinylidene fluoride) (PVDF), have emerged as preferred materials for flexible electronics and sensors owing to their excellent electro-mechanical attributes and ease of fabrication. The efficacy of PVDF composites is significantly influenced by the fillers and the proportion of the β-phase present. This research details the synthesis of La 0.7 Ba 0.3 MnO 3 (LBMO) particles via solid-state reaction, surface-functionalized with acetic acid, and subsequently introduced as nucleating agents into Poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) to fabricate LBMO/P(VDF-HFP) composite membranes. The LBMO fillers before modification significantly increased the β-phase content from 32.7 % to 87.8 % in 5 wt% unmodified LBMO/P(VDF-HFP) membranes. After modification, the hydroxyl groups attached to acetic acid-modified LBMO form hydrogen bonds with -CF 2 groups in P(VDF-HFP), inducing the formation of the β phase while enhancing macroscopic polarization and piezoelectricity. At a 7.5 wt% acetate-modified LBMO doping level, the composite membrane exhibits a β-phase content of 64.5 %, but concurrently enhancing the film's dielectric properties. At 103 Hz, the dielectric constant of 5 wt% modified LBMO/P(VDF-HFP) membrane increases to 24.8, with a minimal rise in dielectric loss from 0.0293 to 0.0314. Moreover, under a 10 N compressive load at 1 Hz, the 5 wt% modified LBMO/P(VDF-HFP) composite achieves an open-circuit voltage of 4.3 V. These improved dielectric and piezoelectric properties indicate the composite's suitability for energy harvesting applications. [ABSTRACT FROM AUTHOR]

We present the design and evaluation of a simple, compact and efficient electromagnetic energy harvesting tile that can be used to harness energy from footsteps. The proposed harvester incorporates a translational–rotational origami-inspired coupling mechanism to transform the axial loads exerted by human footsteps into a localized rotation of an electromagnetic generator. The coupling mechanism employs a non-rigid tunable Kresling spring, the restorative behaviour of which is tunable to maximize energy transduction from the applied load to the generator. A computational model is developed to optimize the design parameters of the mechanism, which are then utilized to fabricate a prototype of the energy harvester. The tile is tested under loading conditions that mimic a human step, where it is demonstrated that it is capable of generating 4.18 W of electrical power per step with a surface power density of 2609 μW cm−2. This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'. [ABSTRACT FROM AUTHOR]

Magneto‐mechano‐electric (MME) energy harvesters (EHs) have emerged as a promising solution for powering Internet of Things (IoT) sensor networks by capturing ambient stray magnetic fields in urban circumstance. Despite significant advancements, achieving milliwatt‐level power generation from extremely weak (<1 Oe) and randomly oriented magnetic fields remains challenging. Drawing inspiration from the configuration of cross‐shaped spider legs, this study introduces an innovative X‐shaped MME‐EH featuring fourfold symmetric architecture with symmetrically distributed magnets at each end, enabling near‐isotropic in‐plane omnidirectional energy harvesting. Under extremely weak magnetic fields 0.75 and 0.3 Oe at 60 Hz, the device achieves a record‐high output power of 7.31 and 1.67 mWRMS, respectively, representing a 362% improvement in normalized power over the state‐of‐the‐art results. The theoretical model attributes these gains to the synergistic enhancement effect of the second bending mode and the dual‐mode structure, collectively improving both magnetomechanical and electromechanical coupling by augmenting the magnetic moments and suppressing the clamp loss. The device further demonstrates robust real‐world applications, efficiently powering a wireless IoT sensor system by harvesting multidirectional magnetic field energy from household appliances. This work opens new avenues for developing efficient multimodal MME‐EHs capable of harnessing omnidirectional, weak magnetic fields for widespread IoT applications. [ABSTRACT FROM AUTHOR]

Harnessing energy from underwater bubbles has garnered significant attention, particularly for powering off‐grid circuitry. However, the efficiency of bubble‐driven liquid‐solid interface charge transfer remains low. This research unveils a phenomenon: accelerated bubble slippage enhances liquid‐solid interfacial charge transfer. Building upon this discovery, a pulse bubble‐based power generation technique is proposed, achieving an energy density of 24.2 mJ L−1 generated by pulsed bubbles. The crux of pulse bubble power generation lies in the precise control of impact velocity. By meticulously regulating the impact kinetic energy of bubbles, the accumulated potential energy of multiple small bubbles is converted into instantaneous pulse kinetic energy. A typical pulse bubble is controlled within a 72 ms timeframe, unleashing a surge of energy that can directly illuminate 400 light‐emitting diodes. This approach represents a groundbreaking advancement in underwater energy harvesting technology, dramatically expanding its potential applications. [ABSTRACT FROM AUTHOR]

The present research focuses on the electrical properties of lead-free piezoceramics (0.985- x)(K 0.485 Na 0.485 Li 0.03)(Nb 0.96 Sb 0.04)O 3 -0.015(Bi 0.5 Na 0.5)ZrO 3 - x SnO 2 (KNNLS-BNZ- x SnO 2 , x = 0.003, 0.006, 0.009, 0.012, and 0.015). This study examines the influence of varying SnO 2 doping levels on the microstructure and piezoelectric properties of the ceramics. All the ceramics prepared demonstrate pure perovskite structure without any secondary phases. The Rietveld refinement analysis of XRD data reveals the existence of multiphase evolution around room temperature. The tetragonality (c/a) and cell volume of the ceramics tend to rise with an increase in Sn4+ content, potentially leading to improved ferroelectric characteristics. The optimum values obtained were Curie temperature (T c) = 395 oC, remnant polarization (P r) = 21.07 μC/cm2, piezoelectric coefficient (d 33)=357 pC/N, piezoelectric voltage constant (g 33) = 24 × 10−3 Vm/N, and figure of merit (FOM off) = 10.34 pm2/N, corresponding to the ceramic doped with x = 0.012 SnO 2. The findings indicate that an optimal amount of Sn4+ in the host composition KNNLS-BNZ improves piezoelectric properties by constructing an R-O-T phase boundary near room temperature. This study suggests that the ceramic with x = 0.012 SnO 2 exhibits a favorably high T c coupled with an exceptional energy harvesting capability, making it a suitable candidate for energy harvesting applications. [ABSTRACT FROM AUTHOR]

Global energy demand is increasing day by day and this has led to the discovery of developed technologies to produce the required energy. Heat is a very common source to generate electric energy however the efficiency of equipment using heat as an energy generation source is limited, and it creates huge amounts of heat energy as waste. One of the technologies which has attracted significant attention in the last two decades is thermoelectric generators (TEGs) that can generate electricity from waste heat. After quick research, it is obvious that different active and passive devices can be manufactured not only for big size energy generators but also for the small size and wearable generators which use heat in order to create electric energy via TEGs. In this review, promising results gathered from different applications of TEGs in different industries claimed as well as the basic principles of thermoelectricity and fundamentals of energy harvesting process from temperature gradient. Experiments on TEGs were done by many researchers as well as analytical models through the years, and validated that TEGs are useful for the energy generation. This work points out the relationship between heat sources and thermoelectric modules (TEMs) and can represent beneficial information for the optimization and application of TEGs. [ABSTRACT FROM AUTHOR]

Solar energy harvesting and storage are essential in the future mix of renewable energy technologies. Hierarchical coral‐structured coatings have been shown to yield high solar absorptance in concentrating solar thermal (CST) systems. However, interfacial delamination and scalability challenges owing to material complexity pose significant hurdles for the widespread industrial adoption of these hierarchical CST coatings. Here, a coral‐structured coating is proposed whose black pigments are strongly bonded by titania, which is a material that mitigates interfacial delamination. Importantly, this coating follows a facile deposition procedure suitable for large‐scale solar receivers. The drone‐deposited coating inhibits cation diffusion and maintains a stable solar absorptance of 97.39±0.20%$97.39\pm 0.20\%$ even after long‐term (3000 h) high‐temperature (800∘C$800 \,^{\circ }\mathrm{C}$) aging. The scalability of developed coating represents a substantial advancement in the implementation of light‐trapping enhancement and maintenance approaches across a wide range of CST applications. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) combine contact electrification and electrostatic induction effects to convert waste mechanical energy into electrical energy. As conventional devices contribute to electronic waste, TENGs based on ecofriendly and biocompatible materials have been developed for various energy applications. Owing to the abundance, accessibility, low cost, and biodegradability of biowaste (BW), recycling these materials has gained considerable attention as a green approach for fabricating TENGs. This review provides a detailed overview of BW materials, processing techniques for BW‐based TENGs (BW‐TENGs), and potential applications of BW‐TENGs in emerging bioelectronics. In particular, recent progress in material design, fabrication methods, and biomechanical and environmental energy‐harvesting performance is discussed. This review is aimed at promoting the continued development of BW‐TENGs and their adoption for sustainable energy‐harvesting applications in the field of bioelectronics. [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators (PENGs), the current pathway to sustainable energy harvesting, are mostly comprised of bulk oxide ceramics which are toxic, rigid, and costly to synthesize. A suitable alternative to them is flexible polar polymers like polyvinylidene fluoride (PVDF), but stabilizing its polar phase is also a daunting task. all these aforementioned issues by employing a biocompatible have been solved, above‐room‐temperature (Tc > 390 K) ferroelectric discrete molecular complex [Cu(L‐His)(bpy)]ClO4.1.5H2O (Cu‐FE) which is not only suitable for piezoelectric energy harvesting due to its large values of piezoelectric co‐efficient (d33 = 17 pm V−1) but also is capable of imparting polar β‐phase in PVDF via hydrogen bonding interactions under mild condition (60 °C). Among the PENG devices prepared with the composite films of PVDF and various weight % (w/V) compositions of Cu‐FE, the highest output voltage of 8 V (peak to peak) has been obtained, a power density of 4 µW cm−2, and an output current of 3 µA from the 1 wt.% composite film. The fabricated PENG device also exhibits swift capacitor charging in 40 s, and acts as an excellent pressure sensor, with exceptional sensitivity to low pressures (7 kPa), giving an output of 0.4 V. [ABSTRACT FROM AUTHOR]

A ferroic order, ferrospintronic (FSp) order, arising in some magnetic materials lacking inversion symmetry is reported on. Emerging from a macroscopic spontaneous symmetry breaking of both the time reversal T and the spatial inversion, while maintaining the symmetry, the order parameter is given by the dipolar moment of the spin density PS$P_{\text{S}}$. Herein a model is advanced that fulfills the symmetry requirements mentioned earlier and its properties are investigated. With the aid of a mean‐field theory, its stability against thermal fluctuations is studied and evidence of truly ferroic states that result from breaking its symmetry is provided. Three predictions that can be checked experimentally to distinguish this class of materials from other compounds are provided. In the first place, it is illustrated that FSp systems host the potential for multiferroic behavior. Second, it is shown that the generic FSp system responds under strain by generating spin currents that can be used in spintronic devices, therefore showing a piezospintronic effect. Finally, it is proven that domain walls in the FSp order parameter lead to magnetoresistive effects. All of the findings mentioned earlier are a significant breakthrough in spintronics and multiferroic phenomena and they have wide‐ranging implications for advancing materials and technologies, particularly in computing and energy harvesting. [ABSTRACT FROM AUTHOR]

Summary Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Using leaf spectroscopy, we evaluated the capability of pigment spectral unmixing to calculate the fluorescence quantum efficiency (FQE) and simultaneously retrieve fast absorption changes in a drought and nitrogen deficiency experiment with tomato. In addition, active fluorescence measurements and pigment analyses of xanthophylls, carotenes and chlorophylls were conducted. We observed notable responses in noninvasive proximal sensing‐retrieved FQE values under stress, but as expected, these alone were not enough to identify the constraints in photosynthetic efficiency. Reflectance‐based detection of the 535‐nm peak absorption change was able to complement FQE and indicate the activation of regulated heat dissipation for both stress treatments under growing light conditions. However, further complexity in the light harvesting energy regulation needs to be accounted for when considering additional light stress. Our results underscore the potential of complementary in vivo quantitative spectroscopy‐based products in the early and nondestructive stress diagnosis of plants, marking the path for further applications. [ABSTRACT FROM AUTHOR]

The concept of multisource energy harvesting has attracted attention in order to harvest multiple types of energy in a single material. In this work, Pb‐free (Ba,Ca)(Zr,Ti)O3 (BCZT) ceramics were used to investigate a combination of piezoelectric and pyroelectric energy harvesting behavior. The temperature dependence of the permittivity and the pyroelectric coefficient was measured, and the pyroelectric properties of BCZT were expected to improve near its orthorhombic–tetragonal phase transition temperature TO–T (∼40°C). The output voltage and current were measured using a BCZT plate, where the BCZT was oscillated under a temperature gradient to apply mechanical stress and temperature fluctuation simultaneously. The measured output voltage from the combined piezo‐ and pyroelectric contributions at a frequency of 2 Hz and with a load resistance of 10 MΩ was 1.4 times higher than the sole piezoelectric output voltage. The resulting combined output voltage was confirmed by finite element simulation. [ABSTRACT FROM AUTHOR]

The use of graded metamaterials is widespread in the fields of wave manipulation and energy harvesting. However, they have the drawback of causing energy scattering after a certain period due to wave reflection or trapping, known as the rainbow effect, in some cases. To address this issue, we extend the adiabatic theorem to the spatial modulation field to mitigate the impact of the rainbow effect, thereby enhancing transmission at the interface of graded metamaterials. Firstly, an analytical expression for the limiting gradient in the space-adiabatic theorem is derived. Then, it is applied to study the longitudinal wave motion in a spring-mass with graded resonators (SMGR) system and the transversal wave motion in a beam with graded resonators (BGR) system. The numerical study demonstrates that if the spatial gradient of system properties is small enough to satisfy the adiabatic theorem, wave scattering can almost be neglected, and transmission will experience a significant increase compared to the non-adiabatic case. Finally, the critical boundary between adiabatic and non-adiabatic cases is determined using the fitting method. This study introduces a design strategy for graded metamaterials, offering opportunities for communication, sensing, energy harvesting, and various other applications. [ABSTRACT FROM AUTHOR]

Numerous efforts have been devoted to harvesting sustainable energy from environment. Among the promising renewable resources, ambient heat exhibits attractive prospects due to its ubiquity and inexhaustibility, and has been converted into electricity through water evaporation-induced hydrovoltaic approaches. However, current hydrovoltaic approaches function only in low-humidity environments and continuously consume water. Herein, we fabricate a hermetic hydrovoltaic cell (HHC) to harvest ambient heat, and have fully addressed the limitations posed by environmental conditions. Meanwhile, for the first time we develop an internal circulation hydrovoltaic mechanism. Taking advantage of the heterogeneous wicking bilayer structure, we verify that inside the hermetic cell, the ambient temperature fluctuation-induced evaporation and further the water circulation can persist, which sustains the hydrovoltaic effect to convert ambient heat into electricity. More importantly, the hermetic design enables the cell to work continuously and reliably for 160 h with negligible water consumption, unaffected by external influences such as wind and light, making it an excellent candidate for extreme situations such as water-scarce deserts, highly humid tropical rain forests, rainy days, and dark underground engineering. These findings provide an easily accessible and widely applicable route for stably harnessing renewable energy, and more notably, offer a novel paradigm toward leveraging low-grade ambient heat energy via circulation design. In this work, authors developed a hermetic hydrovoltaic cell that generates electricity from ambient heat without consuming water. The device operates continuously for 160 h, unaffected by external conditions like wind and light, making it potentially suitable for various challenging environments. [ABSTRACT FROM AUTHOR]

The modification of ZnO, such as transforming it from 1‐D to 3‐D nanostructures or compositing it with carbon‐based materials, has been extensively explored to enhance light energy harvesting and reduce electron‐hole recombination‐key limitations of ZnO. Herein, the effect of different composite materials, specifically nitrogen‐doped carbon quantum dots (N‐CQDs) and nitrogen, sulfur‐doped carbon quantum dots (N,S‐CQDs), on ZnO's morphology and photocurrent response was studied. Various morphologies were synthesized on conductive glass substrate using a one‐pot hydrothermal method, including flower‐like structure for ZnO/N‐CQDs (∼d = 0.9 µm) and multilayered microspheres for ZnO/N,S‐CQDs (∼d = 1.1 µm). The inclusion of sulfur atoms in the composite resulted in a reduced bandgap value from 3.22 to 3.11 eV, along with enhanced light absorption efficiency and improved separation of photogenerated electron‐hole pairs. Furthermore, the crystallinity of ZnO/N,S‐CQDs was significantly enhanced compared to ZnO without sulfur doping. These improvements were reflected in the photoelectrochemical (PEC) measurements, where ZnO/N,S‐CQDs showed a current density of 21.8 µA/cm2 at 0.5 V (vs. Ag/AgCl), which is 5.5 times higher than that of ZnO/N‐CQDs (4.0 µA/cm2). These findings demonstrate that sulfur doping improves photocatalytic efficiency, making 3D ZnO/N,S‐CQDs a promising candidate for various UV‐driven PEC applications. [ABSTRACT FROM AUTHOR]

Polar 2D materials hold the emerging functionalities such as ferro‐, piezo‐, and pyro‐electric properties. On account of infrared‐active low bandgap and polar nature at reduced dimensionality, they served as an ideal choice of pyroelectric material. It can cover up a diverse range of applications, such as waste thermal energy harvesting, IR imaging, photodetector, temperature sensors, and several catalytic processes due to the abundance of dynamic thermal fluxes. Recently, 2D pyroelectric materials have manifested a substantial role in thermal energy harvesting. Consequently, it is realized that there are plenty of scopes available to diversify its applicability. Thus, the challenges are spotlighted in this perspective to envision the desired 2D pyroelectric materials to achieve the effective thermal energy harvesting, sensing, and catalytic efficacy. Particularly, the emphasis is given to elucidate the role of spontaneous polarization in 2D materials to ascertain the giant pyroelectricity. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric energy harvesters (FPEHs) have wide applications in mechanical energy harvesting, portable device driving, and piezoelectric sensors. However, the poor output performance of piezoelectric energy harvesters and the intrinsic shortcoming of piezoelectric sensors that can only detect dynamic pressure limit their further applications. BaTiO3 (BT) and PVDF are deposited on the glass fiber electronic cloth (GFEC) by impregnation and spin‐coating methods, respectively, to form BT‐GFEC/PVDF piezoelectric composite films. A mixed solution of mechanoluminescence (ML) particles ZnS:Cu and PDMS are used as the encapsulation layer to construct a high‐performance ML‐FPEH with self‐powered electrical and optical dual‐mode response characteristics. Due to the interconnection structure of the piezoelectric films, the prepared ML‐FPEH illustrates a high effective energy harvesting performance (≈58 V, ≈43.56 µW cm−2). It can also effectively harvest mechanical energy from human activities. More importantly, ML‐FPEH can sense stress distribution of hand‐writing via ML to achieve stress visualization, making up for the shortcomings of piezoelectric sensors. This work provides a new strategy for endowing FPEH with dual‐mode sensing and energy harvesting. [ABSTRACT FROM AUTHOR]

ABSTRACT The exceptional optoelectronic capabilities of all‐inorganic metal halide perovskite semiconductor components open up a multitude of possible applications. Among all the metal halides, the chloride of cesium cadmium has not been investigated in great detail. Here, we describe a straightforward method for creating CsCdCl3 perovskite single crystals using the slow evaporation solution growth approach. These were investigated by utilizing X‐ray powder diffraction, and optical and impedance spectroscopies. The creation of a single‐phase with a hexagonal‐type structure was verified by the X‐ray powder diffraction (XRPD) data. The compound's semiconductor characteristics were verified by the optical measurement, indicating a direct band‐gap value of about 3.16 eV. The absorption and reflectance spectrum was also used to calculate and explain the optical extinction coefficient, Urbach energy, and skin depth as functions of the input photon's wavelength. Besides, the impedance spectroscopy technique was employed to investigate the characteristics of this component, across a frequency range of 10−1 Hz to 106 Hz and at temperatures ranging from 313 K to 453 K. The frequency behavior of the AC conductivity, σac, was analyzed using the universal Jonscher law. The outcomes of the charge transport investigation on CsCdCl3 imply that the perovskite material possessed a quantum mechanical tunneling (QMT) model for T < 363 K and a large polaron tunneling (OLPT) paradigm for T > 363 K. A correlation between the ionic conductivity and the crystal structure was established and discussed. Ultimately, the low dielectric loss and high dielectric constant of CsCdCl3 make it a promising material for energy harvesting devices. [ABSTRACT FROM AUTHOR]

Highlights Three‐component piezoelectric composites, with castor‐oil‐derived polyurethane (COPU) as the matrix, reinforced with barium titanate (BTO) microparticles (as the primary piezo‐active inclusion) and with multiwalled carbon nanotubes (MWCNTs) were synthesized. BTO content is varied (3, 12, and 25 vol%), while the MWCNTs content is maintained constant at 0.65 wt% (0.37 vol%) w.r.t. the COPU matrix. The addition of MWCNTs significantly enhances the piezoelectric strain coefficient (d33$$ {d}_{33} $$), relative dielectric constant (k/k0), and piezoelectric response, that is, open circuit voltage (VOC) of the piezo‐composites. The (COPU/MWCNTs)/25 vol% BTO composite gives a d33$$ {d}_{33} $$ value of 1.8 ± 0.1 pC/N, an increase of ~1.38 times compared to COPU/25 vol% BTO composite (with a d33$$ {d}_{33} $$ value of 1.3 ± 0.1 pC/N). The relative dielectric constant (k/k0) value of two‐component COPU/BTO (25.0 vol%) increased from 10.34 ± 0.06 to 11.15 ± 0.05 by addition of 0.65 wt% MWCNTs. A maximum open circuit voltage of ~19.6 V for three‐component (COPU/MWCNTs)/ 25 vol% BTO composite was obtained at 45 N load and at 5 Hz frequency. This value (VOC) is ~1.29 times higher compared to COPU/25 vol% BTO composite (with VOC ~ 15.2 V). The k/k0 and d33$$ {d}_{33} $$ values and elastic moduli obtained via experiments were further compared with those obtained from finite element analyses based on kinematic uniform boundary conditions (KUBC) and from Eshelby–Mori–Tanaka micromechanics extended to the domain of linear piezoelectric composites. Castor‐oil‐derived (COPU/MWCNTs/BTO) three‐component composites were synthesized Integration of MWCNTs enhances d33$$ {d}_{33} $$ by ~1.38 times for COPU/25 vol% BTO Elastic modulus and electrical conductivity increased with the addition of MWCNTs Computational predicted k/k0 and d33$$ {d}_{33} $$ values closely match to experimental data [ABSTRACT FROM AUTHOR]

Thermoelectric generators held great promise through energy harvesting from waste heat. Their practical application, however, is greatly constrained by poor raw material utilization and tedious processing in fabricating desired shapes. Herein, a state‐of‐the‐art process is reported for 3D printing the half‐Heusler (Nb0.88Hf0.12FeSb) thermoelectric material using laser powder bed fusion (LPBF). The multi‐dimensional intra‐ and inter‐granular defects created by this process greatly suppress thermal conductivity by providing numerous phonon scattering centers. The resulting LPBF‐fabricated half‐Heusler exhibits a high figure of merit ≈1.2 at 923 K and a single‐leg maximum efficiency of ≈3.3% at a temperature difference (ΔT) of 371 K. Hafnium oxide nanoparticles generated during LPBF effectively prevent crack propagation, ensuring competent mechanical performance and reliable thermoelectric output. The findings highlight the significant potential of LPBF in driving the next industrial revolution of highly efficient and customizable thermoelectric materials. [ABSTRACT FROM AUTHOR]

ABSTRACT In this paper, a robust low‐power power‐on‐reset (POR) circuit with dual threshold method is proposed. The current‐based circuit exhibits good robustness with respect to process, voltage, temperature, and supply ramp variations. In contrast to conventional delay‐based pulse generation approaches, a dual threshold method is introduced to generate POR and brown‐out‐reset (BOR) pulse signals, resulting in ultralow quiescent current and a compact area. Implemented in the 55‐nm CMOS process, the proposed circuit achieves an accurate trigger‐point voltage with a temperature coefficient of 90.4 ppm/°C and a deviation to the ramp time of 2.9% for a range from 100 μs to 1 s. Furthermore, the quiescent current and active area are 0.3 nA and 4834 μm2, respectively, making it particularly suitable for energy harvesting systems. [ABSTRACT FROM AUTHOR]

Highlights Copper based metal–organic frameworks (Cu‐MOF) incorporated poly(vinylidene fluoride) (PVDF) composites were processed using drop casting, with different concentrations of Cu‐MOF (0.15–2 wt.%). Ultrasonication and centrifugation of Cu‐MOF particles were adopted as pre‐processing steps to ensure effective de‐agglomeration of the Cu‐MOF particles. The formation of polar β‐crystalline phase in PVDF/Cu‐MOF composite was confirmed by the morphological observation of fibrillar microstructure and the manifestation of specific absorption bands via spectroscopic analysis. Further, FTIR and NMR spectroscopic analyses unequivocally established the interfacial interactions between Cu‐MOF particles and PVDF dipoles. A maximum of ~92% polar fraction and ~25 pm/V d33 was obtained in PVDF composite of 1 wt.% of Cu‐MOF. Dielectric and ferroelectric investigations were carried out to relate the improvement of the interfacial polarization. Moreover, energy harvesting devices were fabricated from PVDF/MOF composites and a maximum rectified piezoelectric voltage of ~40 V was recorded during finger tapping experiment in PVDF/MOF composite of 1 wt.% Cu‐MOF. Further, a load current and maximum volumetric power density of 7.5 μA and ~1.2 mW/cm3, respectively, were achieved. The usage of the fabricated device as an energy harvester was further established by charging and discharging different capacitors and illuminating LEDs. Cu‐MOF (0.15–2 wt.%) incorporated PVDF composites were processed by solution casting. A maximum of ~92% polar fraction was obtained in PVDF/1MOF composite. A maximum rectified output voltage of ~40 V was recorded in PVDF/1MOF composite. A higher power density (1.2 mW/cm3) and load current (7.5 μA) were achieved for PVDF/1MOF. The usage of the fabricated device as an energy harvester was further established. [ABSTRACT FROM AUTHOR]

In the past decade, organic mixed ion-electron conductors have been successfully adopted in innovative bioelectronic, neuromorphic, and electro-optical technologies, as well as in multiple energy harvesting and printed electronics applications. However, despite the intense research efforts devoted to these materials, organic mixed conductors have not yet found application in electronic/photonic devices operating in key regions of the electromagnetic spectrum, such as the microwave (>5 GHz) and terahertz (0.1-10 THz) ranges. A possible reason for this technological gap is the widespread notion that organic electronic materials are unsuitable for high-frequency applications. In this work, we demonstrate for the first time the utility of high-performance polymer mixed conductors as electro-active tuning layers in reconfigurable terahertz metasurfaces, achieving modulation performances comparable with state-of-the-art inorganic and 2D semiconductors. Through time-domain terahertz spectroscopy, we show that the large conductivity modulations of these polymers, until now probed only at very low frequencies, are effectively preserved in the terahertz range, leading to optimal metadevice reconfigurability. Finally, we leverage the unique processability of organic materials to develop fully direct-written electrically tuneable metasurfaces onto both rigid and flexible substrates, opening new opportunities for the mass-scale realization of flexible and light-weight terahertz optics with unique mechanical characteristics and environmental footprint. Organic mixed ion-electron conductors are emerging as promising platforms for innovative bioelectronic, neuromorphic, and electro-optical technologies. In this work, authors explore the potential of this class of electronic materials in THz technologies by developing reconfigurable metasurfaces via direct-writing methods. [ABSTRACT FROM AUTHOR]

A high‐nuclearity titanium‐oxide cluster (TOC), Ti31O52(OiPr)4Bz24 (denoted as Ti31; Bz=PhCO2), was synthesized via a seed‐mediated synthesis method during the solvothermal reaction of the super‐Keggin cluster Ti17O24(OiPr)20 (denoted as Ti17) and Ti(OiPr)4. Single‐crystal X‐ray diffraction analyses indicate that Ti17 acts as a template for the addition of two Ti7O6 rings to form Ti31. The optical absorption edge of Ti31 slightly shifts to 446 nm, relative to the 419 nm absorption edge of Ti17. Ti31 has much better visible‐light response and charge‐separation properties than Ti17, as confirmed by electrochemical impedance, photoluminescence spectroscopy, and transient photocurrent response. Ti31 also shows much better activity and stability than Ti17 in the solar synthesis of cyclocarbonate through CO2/epoxide cycloaddition. This study not only provides a high‐nuclearity member of the TOC family, but also suggests a potential method to enhance the photocatalytic activity of the known TOCs for more efficient solar energy harvesting. [ABSTRACT FROM AUTHOR]

To alleviate resource shortage and environmental pollution, solar energy can be converted into thermal energy stored in phase change materials and in turn generate electrical energy. To enhance the solar energy utilization efficiency of solar‐thermal‐electrical conversion devices and prevent the heat loss to the environment at night, an intelligent solar‐responsive phase‐change system is innovatively designed consisting of a graphene aerogel film/paraffin wax stamen with an ultra‐high thermal conductivity of 46.7 W m−1 K−1, and thermally preserving aerogel film/liquid crystal elastomer bilayer petals that can bend solar‐responsively by the synergistic effect of solar‐thermal energy conversion and heat‐induced contraction. The solar‐responsive phase‐change system achieves daytime blooming for solar‐thermal conversion with simultaneous energy storage and nighttime closing for minimizing heat loss to the environment, exhibiting a high solar‐thermal conversion and energy storage efficiency of 89.4% and delaying its temperature drop by the thermal preservation effect of the petals. The assembled solar‐responsive solar‐thermal‐electric generator can reach an output voltage of 1033.8 mV at a light intensity of 500 mW cm−2 and continue to generate electrical energy during nighttime, holding tremendous promise in efficient solar energy conversion, storage, and utilization. [ABSTRACT FROM AUTHOR]

A novel approach is proposed for combining phosphor materials with triboelectric nanogenerators (TENGs) for mechanical energy harvesting and illumination applications. For this purpose, strongly reddish‐orange‐emitting Ba0.5Sr0.5Nb2O6:0.25 mol Eu3+ (BSNb:0.25Eu) phosphor materials are synthesized. The photoluminescence properties of the synthesized BSNb:0.25Eu are analyzed. The synthesized BSNb:0.25Eu is utilized as a dielectric filler inside a polydimethylsiloxane polymeric film due to its high dielectric properties to improve the overall dielectric properties of the composite film (CF). TENG devices are fabricated using phosphor‐loaded CFs as the tribonegative layer, transparent polyvinyl alcohol as the tribopositive layer, and aluminum as the conductive electrode. All the TENGs operate in a contact‐separation mode, and the highest electrical output is attained by optimizing the phosphor filler concentration in the CF. The optimized TENG exhibits excellent stability in long‐term operational tests, under varying harsh ambient temperatures. Indium tin oxide sputtered on both triboelectric films as an electrode and combined with a transparent hard substrate to obtain a fully transparent TENG. A self‐illuminating TENG (SI‐TENG) is fabricated by integrating near‐ultraviolet light‐emitting diodes between two identical TENGs. The SI‐TENG can harvest the mechanical energy available in the surrounding environment and illuminate it as a light source. Additionally, the proposed phosphor‐loaded polymer films can be employed for optical thermometry and mechanical energy harvesting via SI‐TENG on a large scale. [ABSTRACT FROM AUTHOR]

Developing polymer‐based piezoelectric materials with multistimulus responsiveness is highly desirable for advancing multi‐source energy harvesting in wearable electronics. Inspired by the multifunctionality of muscle fibers, a nanostructure interface engineering strategy to create piezoelectric polymeric nanoheterostructures (PNHs) with remarkable responsiveness to both mechanical and nonmechanical contactless stimuli is introduced. Through precise interfacing of polymer nanofibers with nanoparticles via multiscale‐regulated interface electrostatic and chemical interactions, the study achieves a controlled assembly of stabilized and hierarchically organized nanoheterostructures featuring unique interface‐confined configurations. These configurations induce in situ stabilized dipole orientation and significant geometric stress nano‐confinement at interfaces, crucial for amplifying electricity generation. Compared to conventional polymer nanocomposites, engineered PNHs exhibit dramatically enhanced piezoelectricity, boasting a higher sensitivity of 1065 mV kPa−1 and piezoelectric coefficient of 76.2 pC N−1. Furthermore, PNHs demonstrate superior thermo‐actuated electricity generation under temperature fluctuations through cooperative spontaneous polarizations of constituent nanostructures, yielding a higher pyroelectric coefficient of 3.13 µC m2K−1. Additionally, the design enables photothermally‐activated switchable electricity generation and light‐energy harvesting, achieving a photo‐electric conversion efficiency tenfold higher than nanocomposites. This effective and versatile approach inspires the development of multi‐responsive nanogenerators for multi‐energy harvesting and self‐powered multistimulus‐sensing applications. [ABSTRACT FROM AUTHOR]