Search Results (482)

Kagome lattices have attracted significant research interest due to their unique interplay of geometry, topology, and material properties. They provide deep insights into strongly correlated electron systems, novel quantum phases, and advanced material designs, making them fundamental in condensed matter physics and material engineering. This work presents an efficient method for terahertz (THz) wave generation across the entire THz spectrum, leveraging high-quality-factor Kagome-shaped silicon photonic crystal resonators. In the proposed simulation-based approach, an infrared (IR) single-frequency wave interacts with an induced resonance mode within the resonator, producing a THz beat frequency. This beat note is then converted into a standalone THz radiation (T-ray) wave using an amplitude demodulator. Simulations confirm the feasibility of our method, demonstrating that a conventional single-frequency wave can induce resonance and generate a stable beat frequency. The proposed technique is highly versatile, extending beyond THz generation to frequency conversion in electronics, optics, and acoustics, among other domains. Its high efficiency, compact design, and broad applicability offer a promising solution to challenges in THz technology. Furthermore, our findings establish a foundation for precise frequency manipulation, unlocking new possibilities in signal processing, sensing, detection, and communication systems. Full article

Hydrogen and oxygen serve as energy carriers that can ease the transition of energy due to their high energy densities. Nonetheless, their production processes entail the development of efficient and low-cost storage and conversion technologies. In this regard, photoelectrocatalysts are materials based on the photoelectronic effect where electrons and holes interact with H₂O, producing H₂ and O_2, and in some cases, this is achieved with acceptable efficiency. Although there are several reviews on this topic, most of them focus on traditional semiconductors, such as TiO₂ and ZnO, neglecting others, such as those based on non-noble metals and organic ones. Herein, semiconductors like CdSe, NiWO₄, Fe₂O₃, and others have been investigated and compared in terms of photocurrent density, band gap, and charge transfer resistance. In addition, this brief review aims to discuss the mechanisms of overall water-splitting reactions from a photonic point of view and subsequently discusses the engineering of material synthesis. Advanced composites are also addressed, such as WO₃/BiVO₄/Cu₂O and CN-FeNiOOH-CoOOH, which demonstrate high efficiency by delivering photocurrent densities of 5 mAcm⁻² and 3.5 mA cm⁻² at 1.23 vs. RHE, respectively. Finally, the authors offer their perspectives and list the main challenges based on their experience in developing semiconductor-based materials applied in several fields. In this manner, this brief review provides the main advances in these topics, used as references for new directions in designing active materials for photoelectrocatalytic water splitting. Full article

Semiconductor photonic nanowires are critical components for nanoscale light manipulation in integrated photonic and electronic devices. Optimizing their optical performance requires enhanced photon conversion efficiency, for which a promising solution is to combine semiconductors with noble metals, using the surface plasmon resonance of noble metals to enhance the photon absorption efficiency. Here, we report plasmon-enhanced light emission in a hybrid nanowire device composed of perovskite semiconductor nanowires and silver nanoparticles formed using superfluid helium droplets. A cesium lead halide perovskite-based four-layer structure (CsPbBr₃/PMMA/Ag/Si) effectively reduces the metal’s plasmonic losses while ensuring efficient surface plasmon–photon coupling at moderate power. Microphotoluminescence and time-resolved spectroscopy techniques are used to investigate the optical properties and emission dynamics of carriers and excitons within the hybrid device. Our results demonstrate an intensity enhancement factor of 29 compared with pure semiconductor structures at 4 K, along with enhanced carrier recombination dynamics due to plasmonic interactions between silver nanoparticles and perovskite nanowires. This work advances existing approaches for exciting photonic nanowires at low photon densities, with potential applications in optimizing single-photon excitations and emissions for quantum information processing. Full article

The terahertz (THz) region of the electromagnetic spectrum, spanning from 0.1 to 30 THz, represents a prospering area in photonics, with transformative applications in imaging, communications, and material analysis. However, the development of efficient and compact THz sources has long been hampered by intrinsic material limitations, inefficient conversion processes, and complex phase-matching requirements. Recent breakthroughs in nonlinear optical mechanisms, resonant metasurface engineering, and advances in the fabrication processes for materials such as lithium niobate (LN) and aluminum gallium arsenide (AlGaAs) have paved the way for innovative THz generation techniques. This review article explores the latest theoretical advances, together with key experimental results and outlines perspectives for future developments. Full article

Polyetheretherketone (PEEK) is a high-performance, biocompatible polymer with remarkable mechanical properties, making it a promising candidate for medical implants. However, its intrinsic radiolucency poses a challenge for post-operative imaging. This study investigates the photon shielding capabilities and X-ray imaging qualities of pure PEEK and its composites with barium sulfate (BaSO₄), tantalum (Ta), bismuth oxide (Bi₂O₃), and hydroxyapatite (HA). The Monte Carlo-based Geant4 toolkit and the EpiXS application were used to evaluate key photon interaction parameters, including mass attenuation coefficients, effective atomic number (Z_eff), and effective electron density (N_eff), as well as the imaging performance metrics such as energy deposition and signal-to-noise ratio (SNR). Results indicate that high atomic number composites significantly enhance PEEK’s photon attenuation and imaging contrast. PEEK-Bi₂O₃ exhibited the highest attenuation coefficients and energy deposition, making it the most effective X-ray shielding material. PEEK-Ta provided a balanced performance with enhanced shielding and lower secondary radiation effects, making it suitable for applications requiring both radiopacity and imaging stability. PEEK-BaSO₄ moderately improved attenuation while maintaining a lower density, offering a trade-off between radiopacity and mechanical properties. Conversely, PEEK-HA demonstrated minimal enhancement in photon attenuation, limiting its effectiveness for radiographic applications. The findings suggest that incorporating high atomic number elements into PEEK significantly enhances its suitability for radiopaque medical implants, allowing for improved post-operative monitoring. Full article

Obtaining wide energy-gap semiconductor ultra-thin films is an important aspect for their application in sulfide-based solar cells. By reducing the optical losses associated with light reflection and exhibiting absorption edge shifts towards short wavelengths, these layers can optimize the amount of photons interacting with the active photovoltaic material, which increases the conversion efficiency of the solar cell. Ultra-thin CdS films were prepared by a low-cost chemical synthesis and the impact of silver doping on the optical, structural, and morphological properties was evaluated. SEM micrographs revealed that the layers are ultra-thin, homogeneous and uniform, with a reduction in particle size with increasing doping concentration. X-ray diffraction data confirmed the crystallization of CdS in the hexagonal phase for all prepared samples. A low concentration contributed to the formation of Ag₂S in the monoclinic phase according to the diffractograms. The optical properties of the thin films revealed an absorption edge shift that increased the CdS band gap from 2.267 ± 0.007 to 2.353 ± 0.005 eV with increasing doping concentration, improving the spectral transmittance response. These results make these layers particularly useful for implementation in next-generation flexible photovoltaic devices. Full article

Global cacao production, primarily led by African countries, is facing a crisis, which presents growth potential for South American countries like Colombia, Peru, and Ecuador. However, a significant challenge for these countries is cadmium (Cd) contamination in cacao beans. Agroforestry systems with cacao (CAFSs) improve soil health and can remediate Cd through tree phytoextraction. Effective phytoremediation requires Cd-tolerant, high-biomass species and preferential Cd allocation to stems. This study evaluated the phytoremediation potential of four forest species (Cariniana pyriformis Miers, Terminalia superba Engl. and Diels, Swietenia macrophylla King, and Cedrela odorata L.) under cadmium (Cd) exposure. C. pyriformis exhibited hypertolerance, showing minimal biomass reduction (less than 15%, changing from 1.619 to 1.343 g plant⁻¹) under excess Cd conditions, compared to Cedrela odorata and T. superba, which showed significant biomass reductions. C. pyriformis and T. superba showed notable Cd accumulation in stems (652.99 and 635.39 mg Cd kg⁻¹), an essential feature for wood tree-mediated phytoextraction, while C. odorata allocated more Cd to leaves (35.35 mg Cd kg⁻¹). C. pyriformis maintained high photosynthesis (12.8 μmol CO₂ m⁻² s⁻¹), light use efficiency (0.086 mol CO₂ mol photons⁻¹), and an increased relative growth rate (0.575 g g⁻¹ day⁻¹) under Cd exposure. Overall, C. pyriformis demonstrated significant potential for use in phytoremediation due to its high Cd tolerance (84%), efficient allocation to stems (17%), and sustained physiological performance under Cd exposure. Conversely, C. odorata allocates Cd to leaves (16%), which can reintroduce Cd into the soil, and exhibits a low tolerance index (54%) under higher cadmium contamination. Further studies are still needed to understand the specific mechanisms of Cd accumulation in stems of promising species like C. pyriformis and T. superba. Full article

This study addresses the challenges of efficient, large-scale production of flexible transparent conducting electrodes (TCEs). We fabricate TCEs on polyethylene terephthalate (PET) substrates using a high-speed roll-to-roll (R2R) compatible method that combines gravure printing and photonic curing. The hybrid TCEs consist of Ag metal bus lines (Ag MBLs) coated with silver nanowires (AgNWs) and indium zinc oxide (IZO) layers. All materials are solutions deposited at speeds exceeding 10 m/min using gravure printing. We conduct a systematic study to optimize coating parameters and tune solvent composition to achieve a uniform AgNW network. The entire stack undergoes photonic curing, a low-energy annealing method that can be completed at high speeds and will not damage the plastic substrates. The resulting hybrid TCEs exhibit a transmittance of 92% averaged from 400 nm to 1100 nm and a sheet resistance of 11 Ω/sq. Mechanical durability is tested by bending the hybrid TCEs to a strain of 1% for 2000 cycles. The results show a minimal increase (<5%) in resistance. The high-throughput potential is established by showing that each hybrid TCE fabrication step can be completed at 30 m/min. We further fabricate methylammonium lead iodide solar cells to demonstrate the practical use of these TCEs, achieving an average power conversion efficiency (PCE) of 13%. The high-performance hybrid TCEs produced using R2R-compatible processes show potential as a viable choice for replacing vacuum-deposited indium tin oxide films on PET. Full article

In recent decades, substantial progress has been made in embedding molecules, nanocrystals, and nanograins into nanofibers, resulting in a new class of hybrid functional materials with exceptional physical properties. Among these materials, functional nanofibers exhibiting ferroelectric, piezoelectric, pyroelectric, multiferroic, and nonlinear optical characteristics have attracted considerable attention and undergone substantial improvements. This review critically examines these developments, focusing on strategies for incorporating diverse compounds into nanofibers and their impact on enhancing their physical properties, particularly ferroelectric behavior and nonlinear optical conversion. These developments have transformative potential across electronics, photonics, biomaterials, and energy harvesting. By synthesizing recent advancements in the design and application of nanofiber-embedded materials, this review seeks to highlight their potential impact on scientific research, technological innovation, and the development of next-generation devices. Full article

Basil (Ocimum basilicum L.) is highly sensitive to environmental conditions and is an ideal candidate for cultivation in controlled environment agriculture (CEA). Light-emitting diode technology has become essential in CEA, offering precise control over light intensity, spectrum, and duration. This study investigated how supplemental blue light, far-red light, or their combination influences basil biomass, morphology, texture, and color when added to a white + red light spectrum. Basil ’Prospera’ and ’Amethyst’ were exposed to five light treatments for 14–28 days: white + red at 180 µmol∙m⁻²∙s⁻¹ (W) as the control, and four treatments with an additional 60 µmol∙m⁻²∙s⁻¹ of either white + red (+W₆₀), blue (+B₆₀), far-red (+FR₆₀), or a combination of B and FR (+B₃₀+FR₃₀), for a total photon flux density of 240 µmol∙m⁻²∙s⁻¹. The results demonstrated that +B₆₀ and +W₆₀ light treatments increased leaf thickness by 17–20% compared to the +FR₆₀ treatment. Conversely, texture analysis revealed that +FR₆₀-treated leaves had higher puncture resistance, with ’Amethyst’ and ’Prospera’ requiring 1.57 ± 0.43 N and 1.45 ± 0.35 N of force, respectively, compared to 1.19 ± 0.32 N and 1.1 ± 0.21 N under +B₆₀. These findings suggest that tailored light recipes in CEA can optimize basil quality, allowing growers to modify traits like leaf color, thickness, and toughness. Full article

We herein report the enhanced electrical properties of self-powered perovskite-based photodetectors with high sensitivity and responsivity by applying the surface passivation strategy using C₆₀ (fullerene) as a surface passivating agent. The perovskite (CH₃NH₃PbI₃) thin film passivated with fullerene achieves a highly uniform and compact surface, showing reduced leakage current and higher photon-to-current conversion capability. As a result, the improved film quality of the perovskite layer allows excellent photon-detecting properties, including high values of external quantum efficiency (>95%), responsivity (>5 A W⁻¹), and specific detectivity (>10¹³ Jones) at zero bias voltage, which surpasses those of the pristine perovskite-based device. Furthermore, the passivated device showed fast rise (0.18 μs) and decay times (17 μs), demonstrating high performance and ultrafast light-detecting capability of the self-powered perovskite-based photodetectors. Full article

Utilizing the phase-matching conditions of inter-modal four-wave mixing in an elliptical-core few-mode fiber supporting three non-degenerate modes, we experimentally demonstrate schemes for generating orbital-angular-momentum (OAM)-entangled photon pairs with high mode purity and for achieving highly mode-selective frequency conversion of beams in OAM-compatible (LP_11a, LP_11b) mode basis. These techniques expand the toolbox for using OAM modes in both classical and quantum communications and information processing. Full article

Delafossite CuFeO₂ has emerged as a promising earth-abundant p-type photocathode for solar fuel generation due to its stability in aqueous conditions and its favorable light absorption characteristics. However, practical photocurrent generation in CuFeO₂ has consistently fallen short of its theoretical potential. This limitation is attributed primarily to suboptimal practical visible light absorption, resulting in diminished incident photon-to-current conversion efficiency (IPCE). Challenges related to charge separation and transport, originating from low acceptor density and inherent low conductivity, further contribute to the reported suboptimal performance of delafossite CuFeO₂. Thus, the present review comprehensively documents the latest advancements in the field of CuFeO₂ photocathode research, with a particular emphasis on strategies to overcome the challenges currently being faced and on the illustration of pathways that may lead to the enhancement of critical performance parameters such as photocurrents, photovoltage, and fill factor. Full article

As the flux at synchrotron radiation beamlines increases, helium-filled ion chambers are more common to avoid saturation and non-linearities. For helium, this paper will show that the conversion of the current to flux is best performed using the mass-energy cross-section but is complicated by a strong interaction of scattered photons with the ion chamber plates. This makes the conversion highly dependent on the ion chamber geometry, and an accurate flux determination will typically require a calibration. To minimize the sensitivity of the calibration to external influences, it is proposed to add internal scatter baffles to the standard chamber configuration. Full article

Enhancing the performance of organic solar cells (OSCs) is essential for achieving sustainability in energy production. This study presents an innovative strategy that involves fine-tuning the thickness of the bulk heterojunction (BHJ) photoactive layer at the nanoscale to improve efficiency. The organic blend D18:L8-BO is utilized to capture a wide range of photons while addressing the challenge of minimizing optical losses from low-energy photons. The research incorporates SnO₂ and ZnO as electron transport layers (ETLs), with PMMA functioning as a hole transport layer (HTL). A comprehensive analysis of photon absorption, charge carrier generation, localized energy fluctuations, and thermal stability reveals their critical role in enhancing the efficiency of D18:L8-BO active films. Notably, introducing SnO₂ as an ETL significantly decreased losses and modified localized energy, achieving an impressive efficiency of 19.85% at an optimized blend thickness of 50 nm with low voltage loss (ΔV_oc) of 0.4 V within a J_sc of 28 mA cm⁻² by performing an optoelectronic simulation employing “Oghma-Nano 8.1.015” software. In addition, the SnO₂-based structure conserved 88% of the PCE at 350 K compared to room temperature PCE, which describes the high thermal stability of this structure. These results demonstrate the potential of this methodology in improving the performance of OSCs. Full article