Search Results (241)

Organic phase change materials (OPCMs) show immense application potential in solar energy storages owing to high energy storage capacity and latent heat efficiency. However, it is difficult to achieve prolonged energy storage due to the sensitivity of phase change to environmental temperature, and adding other substances will lead to a decrease in total energy density. Herein, azobenzene organic phase change composite (C₁₄Azo-MA) was designed and prepared by doping myristic acid (MA) with an azobenzene derivative (C₁₄Azo) featuring a carbon chain identical to that of the MA matrix. C₁₄Azo-MA was systematically characterized by UV–Visible absorption spectroscopy and differential scanning calorimetry. The results showed that the C₁₄Azo-MA retains the same isomerization properties as the C₁₄Azo dopant. C₁₄Azo-MA, due to its molecular photoisomerization and enhanced intermolecular interactions, establishes a new energy barrier and forms supercooling within C₁₄Azo-MA, thereby allowing the storage of thermal energy below the crystallization temperature of MA. Notably, the C₁₄Azo-MA exhibits a high energy density of 225.08 J g⁻¹, surpassing that of pure MA by 14.42%. This work holds significant potential for solar energy storage applications. Full article

Azobenzene-based hologram recording materials are well known for their rewritable and polarization-selective properties that enable polarization-multiplexed recording and high-density optical storage. High diffraction efficiency, longer retention time, and shorter response time are desirable for rewritable recording materials, but they always require a trade-off relationship. In this study, we show that by simply coating the Azobenzene-based film with multiple layers of a suitable material, these parameters can be improved simultaneously without compromise. Bilayer films and triple layer films were prepared by depositing a DNA–surfactant complex-based layer above and below the azobenzene-based poly(CACzE-MMA) copolymer layer. The hologram recording performance was evaluated in terms of the diffraction efficiency, photoresponse time, and retention behavior of the recorded gratings. Compared with monolayer copolymer films, the multilayer DNA–surfactant complex-based copolymer films exhibited enhanced diffraction efficiency and faster photoresponse. In particular, the bilayer and trilayer structures showed a marked improvement in retention time, indicating suppressed relaxation of refractive index modulation. This enhancement is attributed to molecular confinement at the DNA–surfactant complex and copolymer interfaces generated by the layered architecture. These results demonstrate that a DNA–surfactant complex-based layering approach is an effective strategy for improving hologram stability and highlight the potential of DNA–surfactant complex-derived matrices as effective alternatives to poly(methyl methacrylate) (PMMA) in holographic applications. Full article

In the presented research, aluminum-doped zinc oxide (AZO) thin films were synthesized on high-power transmission lines using the RF magnetron sputtering process. The impact of deposition power (160 W to 280 W) and deposition pressure (2 Pa to 5 Pa), on key characteristics like material composition, wettability, anti-icing behavior, and average crystal size were analyzed. The optimization of wettability and anti-icing performance was carried out using two-factor, four-level design of the Taguchi method to study the combined effects of multiple parameters rather than the effect of a single parameter. Considerable variation in the water contact angle, from 92.3° to 123.6°, has been observed, suggesting an enhancement in hydrophobic nature with optimized condition. Anti-icing tests demonstrated that the coated surface delayed ice accumulation by approximately 4.56 times compared to the uncoated surface. X-ray diffraction (XRD) analysis was carried out to confirm notable changes in the intensity of the (002) peak along the c-axis, directly correlating with grain size modification. The change in surface roughness was studied using AFM and the results were compared to establish a relationship between surface roughness and average grain size. Overall, the findings highlight the critical role of deposition parameters and their interactions in modifying the surface and structural properties of AZO thin films, which demonstrates their potential application for improving the anti-icing performance of transmission lines. Full article

High-quality AZO thin films were produced on a 4-inch Si substrate using large-area PLD equipment at a substrate temperature of 330 °C, with a ZnO: Al (98:2 wt.%) target. This study aims to enhance the electrical, optical, morphological and structural properties of large-area PLD-grown AZO thin films by tuning the deposition pressures. The samples were prepared under high-vacuum (HV) conditions, as well as in oxygen atmospheres of 0.005 mbar O₂, 0.01 mbar O₂, and 0.1 mbar O₂. Consequently, a bilayer AZO film was prepared in a combination of two deposition pressures (first layer prepared under HV, followed by the second layer prepared at 0.01 mbar O₂). Additionally, morphological and structural characterization revealed that high-quality columnar growth AZO thin films free of droplets, with a strong (002) orientation, were achieved on a 4-inch Si substrate. Moreover, Hall measurements in the Van der Pauw configuration were used to assess the electrical properties. A low electrical resistivity of 3.98 × 10⁻⁴ Ω cm, combined with a high carrier concentration (n) of 1.05 × 10²¹ cm⁻³ and a charge carrier mobility of 17.9 cm²/V s, was achieved at room temperature for the sample prepared under HV conditions. The optical characterization conducted through spectroscopic ellipsometry measurements showed that the large-area AZO sample exhibits an increased optical transparency in the visible (VIS) range with a near-zero extinction coefficient (k) and a wide bandgap of 3.75 eV, fulfilling the standards for materials classified as TCO. In addition, the increased thickness uniformity of the prepared AZO films over a large area represents a significant step in scaling the PLD technique for industrial applications. Full article

The photoinitiation properties of two porphyrins were evaluated for the free-radical photopolymerization (FRP) of a bio-based acrylated monomer, i.e., soybean oil acrylate (SOA). Their combination with various co-initiators, such as a tertiary amine as electron donor (MDEA), an iodonium salt as electron acceptor (Iod), as well as two biosourced co-initiators used as H-donors (cysteamine and N-acetylcysteine), makes them highly efficient photoinitiating systems for FRP under visible light irradiation. Electron paramagnetic resonance spin trapping (EPR ST) demonstrated the formation of highly reactive radical species, and fluorescence and laser flash photolysis highlighted the chemical pathways followed by the porphyrin-based systems under light irradiation. High acrylate conversions up to 96% were obtained with these different systems at different irradiation wavelengths (LEDs@385 nm, 405 nm, 455 nm, and 530 nm), in laminate or under air. The final crosslinked and bio-based porphyrin-based materials were used for the full photo-oxidation in water of an azo-dye (acid red 14) and under UV irradiation. These materials have been involved in three successive depollution cycles without any reduction in their efficiency. Full article

Bimetallic mesoporous photocatalysts were synthesized via a wet impregnation method using SBA-15 as a support, and characterized by UV–visible diffuse reflectance spectroscopy, low-angle X-ray diffraction and N₂ physisorption. Among the tested materials, the Ti/Mn combination exhibited the highest photocatalytic activity in azo dye degradation. To understand this enhanced performance, catalysts with varying Mn loads and calcination ramps were evaluated. Additionally, experiments with radical scavengers (isopropanol, chloroform) and under N₂ insufflation were conducted to identify the active radical species. Catalysts prepared with low Mn content and higher calcination ramps showed the greatest activity, which significantly decreased with isopropanol, indicating hydroxyl radicals as the main reactive species. In contrast, samples with higher Mn content and quicker heating displayed reduced activity in the presence of chloroform, suggesting superoxide radical involvement. Spectroscopic analyses (XPS, UV–Vis DRS) revealed that increasing Mn load promotes the formation of Mn²⁺ over Mn⁴⁺ species and lowers the band gap energy. These findings highlight the direct correlation between synthesis parameters, surface composition and optical properties, providing a strategy for fine-tuning the performance of a photocatalyst. Full article

Organic phase change materials (OPCMs) offer high energy density for thermal storage but suffer from crystallization kinetics dependent on ambient temperature, leading to uncontrolled heat release and limited storage lifetime. Although doping OPCMs with azobenzene (Azo) derivatives enables optically controlled energy storage and release, existing systems require UV irradiation for E-to-Z isomerization. This UV dependency seriously hinders their development in practical solar applications. Herein, we develop a visible-light-responsive Azo@OPCM composite by doping tetra-ortho-fluorinated azobenzene into eicosane. Systematic characterization of composites with different dopant ratios via UV–visible spectroscopy and differential scanning calorimetry reveals that green-light irradiation drives E-to-Z isomerization, achieving 97–99% Z-isomer conversion. This photoisomerization could introduce supercooling through photo-responsive energy barriers generated by Z-isomer, allowing thermal energy storage at lower temperatures. Subsequent blue-light irradiation triggers Z-to-E reversion to eliminate supercooling and enable optically controlled heat release. Additionally, by regulating the molar ratios of dopant, the optimized composites achieved 280.76 J/g energy density at 20% molar doping ratio, which surpassed that of pure eicosane and the reported Azo-based photothermal energy storage system. This work establishes a complete visible-light-controlled energy harvesting–storage–release cycle with significant potential for near-room-temperature solar thermal storage applications. Full article

Bulk chalcogenides from the system (GeTe₄)_1−xIn_x, where x = 0; 5 and 10 mol%, were synthesized by a two-step melt quenching technique. New layered composite materials based on them and the azo polymer [1-4-(3-carboxy-4-hydrophenylazo) benzensulfonamido]-1,2-ethanediyl, sodium salt] has been prepared through spin coating, electrospray deposition and via vacuum-thermal evaporation of the chalcogenide and spin coating of the azo polymer onto it. Using the latter technology, a material consisting of one chalcogenide and one azo polymer film and three chalcogenide and three azo polymer films has been fabricated. The carried-out SEM analysis shows that in the materials, initially prepared as a bilayer and multilayer structure, diffusion at the chalcogenide/polymer interface occurs leading to the formation of a homogenous composite environment. Birefringence was induced at 444 nm in all the fabricated thin film materials. The highest value of the maximal induced birefringence has been measured for the material fabricated as a stack, Δn_max = 0.118. For the material prepared as a bilayer structure and the composite material obtained through electrospray deposition, the maximal induced birefringence takes values of Δn_max = 0.101 and Δn_max = 0.095, respectively. The sample prepared via spin coating of the chalcogenide/PAZO dispersion has the lowest value of the maximal induced birefringence (Δn_max = 0.066) in comparison to the pure PAZO polymer film (Δn_max = 0.083). Full article

Transparent conductive aluminum-doped zinc oxide (AZO) films were investigated as potential recombination layers for perovskite/silicon tandem solar cells, comparing the results of atomic layer deposition (ALD) and magnetron sputtering (MS) on vertically aligned silicon nanowire (SiNW) scaffolds. Conformality and thickness control were examined by cross-sectional SEM/TEM and profilometry, revealing fully conformal ALD coatings with tunable thicknesses (40–120 nm) versus tip-capped, semi-uniform MS films (100–120 nm). Optical transmission measurements on glass substrates showed that both 120 nm ALD and MS layers exhibit interference maxima near 450–500 nm and 72–89% transmission across 800–1200 nm; the thinnest ALD films reached up to 86% near-IR transparency. Four-point probe analysis demonstrated that ALD reduces surface resistance from 1150 Ω/□ at 40 nm to 245 Ω/□ at 120 nm, while MS layers achieved 317 Ω/□ at 120 nm. These results delineate the balance between conformality, transparency, and conductivity, providing design guidelines for AZO recombination interfaces in next-generation tandem photovoltaics. Full article

Persistent reactive azo dyes released from textile finishing are a serious threat to water systems, but effective methods using sunlight to break them down are still limited. Everzol Yellow 3RS (EY-3RS) is particularly recalcitrant: past studies have relied almost exclusively on physical adsorption onto natural or modified clays and zeolites, and no photocatalytic pathway employing engineered nanomaterials has been documented to date. This study reports the synthesis, characterization, and performance of a visible-active ternary nanocomposite, Cu₄O₃/ZrO₂/TiO₂, prepared hydrothermally alongside its binary (Cu₄O₃/ZrO₂) and rutile TiO₂ counterparts. XRD, FT-IR, SEM-EDX, UV-Vis, and PL analyses confirm a heterostructured architecture with a narrowed optical bandgap of 2.91 eV, efficient charge separation, and a mesoporous nanosphere-in-matrix morphology. Photocatalytic tests conducted under midsummer sunlight reveal that the ternary catalyst removes 91.41% of 40 ppm EY-3RS within 100 min, markedly surpassing the binary catalyst (86.65%) and TiO₂ (81.48%). Activity trends persist across a wide range of operational variables, including dye concentrations (20–100 ppm), catalyst dosages (10–40 mg), pH levels (3–11), and irradiation times (up to 100 min). The material retains ≈ 93% of its initial efficiency after four consecutive cycles, evidencing good reusability. This work introduces the first nanophotocatalytic strategy for EY-3RS degradation and underscores the promise of multi-oxide heterojunctions for solar-driven remediation of colored effluents. Full article

Transparent conductive oxides (TCOs) have become essential components in a broad range of modern devices, including smartphones, flat-panel displays, and photovoltaic cells. Currently, indium tin oxide (ITO) is used in approximately 90% of these devices. However, ITO prices continue to rise due to the limited supply of indium (In), making the development of alternative materials for TCOs indispensable. Therefore, this study highlights the latest advances in creating new, affordable materials, with a focus on aluminum-doped zinc oxide (AZO). Over the last few decades, this material has been widely studied to improve its physical properties, particularly its low electrical resistivity, which can affect the performance of various devices. Now, it is close to replacing ITO due to several advantages including cost-effectiveness, stability under hydrogen plasma, low processing temperatures, and lack of toxicity. Besides that, in comparison to other TCOs such as IZO, IGZO, or IZrO, AZO achieved a low electrical resistivity (10⁻⁵ ohm cm) while maintaining a high transparency across the visible spectrum (over 85%). Additionally, due to the increasing development of technologies utilizing such materials, it is essential to develop more effective techniques for producing TCOs on a larger scale. Additionally, due to the increasing development of technologies utilizing such materials, it is essential to develop more effective techniques for producing TCOs on a larger scale. This review emphasizes the potential of AZO as a cost-effective and scalable alternative to ITO, highlighting key advancements in deposition techniques such as pulsed laser deposition (PLD). Full article

New bulk chalcogenides from the system (GeTe₆)_1−xCu_x, where x = 5, 10, 15 and 20 mol%, have been synthesized. The structure and composition of the materials were studied using X-ray powder diffraction (XRD) and energy-dispersive spectroscopy (EDS). Scanning electron microscopy (SEM) was applied to analyze the surface morphology of the samples. Some thermal characteristics such as the glass transition, crystallization and melting temperature and some physico-chemical properties such as the density, compactness and molar and free volumes were also determined. The XRD patterns show sharp diffraction peaks, indicating that the synthesized new bulk materials are crystalline. The following four crystal phases were determined: Te, Cu, CuTe and Cu₂GeTe₃. The results from the EDS confirmed the presence of Ge, Te and Cu in the bulk samples in concentrations in good correspondence with those theoretically determined. A layered thin-film material based on Ge₁₄Te₈₁Cu₅, which exhibits lower network compactness compared to the other synthesized new chalcogenides, and the azo polymer PAZO was fabricated, and the kinetics of the photoinduced birefringence at 444 nm was measured. The results indicated an increase in the maximal induced birefringence for the layered structure in comparison to the non-doped azo polymer film. Full article

Ag/AgCl-decorated layered lanthanum oxide (La₂O₃) and niobium pentoxide (Nb₂O₅) plasmonic photocatalysts are fabricated through an ionic liquid-mediated co-precipitation method. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) techniques were used to illustrate the physicochemical properties of the materials. The photoactivity was evaluated for the degradation of Acid Blue 92 (AB92) azo dye, a typical organic contaminant from the textile industry, and U251 cancer cell inactivation. According to the results, Nb₂O₅–Ag/AgCl was able to remove >99% of AB92 solution in 35 min with the rate constant of 0.12 min⁻¹, 2.4 times higher than that of La₂O₃–Ag/AgCl. A pH of 3 and a catalyst dosage of 0.02 g were determined as the optimized factors to reach the highest degradation efficiency under solar energy at noon, which was opted to have the highest sunlight intensity over the reactor. Also, 0.02 mg/mL of Nb₂O₅–Ag/AgCl was determined to be of great potential to reduce cancer cell viability by more than 50%, revealed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and mitochondrial membrane potential (MMP) examinations. The mechanism of degradation was also discussed, considering the key role of Ag⁰ nanoparticles in inducing a plasmonic effect and improving the charge separation. This work provides helpful insights to opt for an efficient rare metal oxide with good biocompatibility as support for the plasmonic photocatalysts with the goal of environmental purification under sunlight. Full article

The safety concerns associated with sensitivity issues regarding long nitrogen chain-based energetic compounds, especially for eight or more catenated nitrogen atoms in backbones, need to be resolved. Incorporating specific functional groups represents a key approach for enhancing stability in organic energetic materials. This study reports the synthesis of 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8), an N8-chain compound featuring strategically placed amide groups. Employing THA(O-tosylhydroxylamine) and KMnO₄, 1,1′-(diazene-1,2-diyl)bis(4-nitro-1H-1,2,3-triazole-5-carboxamide) (S8) was synthesized and underwent N-amination and oxidative azo coupling. Comprehensive characterization, including X-ray diffraction, mechanical sensitivity testing, and theoretical analysis, alongside comparative studies with known N8 compounds, revealed that S8 exhibits unprecedented stability within its class. Among reported N8-catenated nitrogen chain compounds, attributed to the incorporation of the amide functionality, S8 demonstrates the highest impact sensitivity (IS = 10 J) and friction sensitivity (FS = 40 N) while maintaining excellent detonation performance (D = 8317 ms⁻¹, P = 28.27 GPa). This work highlights the amide group as a critical structural part for achieving high stability in sensitive long-nitrogen-chain energetic materials without compromising performance. Full article

The rising demand for sustainable energy solutions has spurred the development of advanced materials for photovoltaic devices. Among these, transparent conductive oxides (TCOs) play a pivotal role in enhancing device efficiency, particularly in silicon-based solar cells. However, the reliance on indium-based TCOs like ITO raises concerns over cost and material scarcity, prompting the search for more abundant and scalable alternatives. This study focuses on the fabrication and characterization of aluminum-doped zinc oxide (ZnO:Al, AZO) thin films deposited via Atomic Layer Deposition (ALD), targeting their application as transparent conductive oxides in silicon solar cells. The ZnO:Al thin films were synthesized by alternating supercycles of ZnO and Al₂O₃ depositions at 225 °C, allowing precise control of composition and thickness. Structural, optical, and electrical properties were assessed using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), Raman spectroscopy, spectroscopic ellipsometry, and four-point probe measurements. The results confirmed the formation of uniform, crack-free ZnO:Al thin films with a spinel-type ZnAl₂O₄ crystalline structure. Optical analyses revealed high transparency (more than 80%) and tunable refractive indices (1.64 ÷ 1.74); the energy band gap was 2.6 ÷ 3.07 eV, while electrical measurements demonstrated low sheet resistance values, reaching 85 Ω/□ for thicker films. This combination of optical and electrical properties underscores the potential of ALD-grown AZO thin films to meet the stringent demands of next-generation photovoltaics. Integration of Zn:Al thin films into silicon solar cells led to an optimized photovoltaic performance, with the best cell achieving a short-circuit current density of 36.0 mA/cm² and a power conversion efficiency of 15.3%. Overall, this work highlights the technological relevance of ZnO:Al thin films as a sustainable and cost-effective alternative to conventional TCOs, offering pathways toward more accessible and efficient solar energy solutions. Full article