Search

This study investigates the process of using multi-walled carbon nanotube (MWCNT) coatings to enhance lamp heating temperatures for solar thermal absorption applications. The primary focus is studying the effects of the self-organized honeycomb structures of CNTs formed on silicon substrates on different cell area ratios (CARs). The drop-casting process was used to develop honeycomb-structured MWCNT-coated absorbers with varying CAR values ranging from ~60% to 17%. The optical properties were investigated within the visible (400–800 nm) and near-infrared (934–1651 nm) wavelength ranges. Although fully coated MWCNT absorbers showed the lowest reflectance, honeycomb structures with a ~17% CAR achieved high-temperature absorption. These structures maintained 8.4% reflectance at 550 nm, but their infrared reflection dramatically increased to 80.5% at 1321 nm. The solar thermal performance was assessed throughout a range of irradiance intensities, from 0.04 W/cm2 to 0.39 W/cm2. The honeycomb structure with a ~17% CAR value consistently performed better than the other structures by reaching the highest absorption temperatures (ranging from 52.5 °C to 285.5 °C) across all measured intensities. A direct correlation was observed between the reflection ratio (visible: 550 nm/infrared: 1321 nm) and the temperature absorption efficiency, where lower reflection ratios were associated with higher temperature absorption. This study highlights the significant potential for the large-scale production of cost-effective solar thermal absorbers through the application of optimized honeycomb-structured absorbers coated with MWCNTs. These contributions enhance solar energy efficiency for applications in water heating and purification, thereby promoting sustainable development. [ABSTRACT FROM AUTHOR]

Abstract We designed an ultra-broadband graphene absorber structure with the applied resonator design based on the Al-AlSb-Cr structure, and a thin effective layer of graphene is inserted. To develop the role of the graphene in solar absorbers, the current structure investigates above 98% for 1500 nm bandwidth and 2800 nm (overall bandwidth) for 93.68%. In this study, the procedure of the investigated design in flow chat configuration, the multi-step presentation of the developed layers, and the analysis of the used parameters will be involved. The design is optimized using machine learning algorithm. The optimized design shows good performance compared to the other system. The newly investigated graphene design can be absorbed not only in visible places but also in near-infrared energy and ultraviolet zones. The other applications of the light trapping process, photovoltaic devices, and energy harvesting can also be used.

Herein, hydrochar is derived from abundant and low‐cost waste sawdust using hydrothermal carbonization in distilled water with a series of temperatures (150, 200, and 250 °C) and time (2 and 3 h), where the hydrochar characteristics are evaluated toward its application as a solar absorber. The hydrochar‐based solar absorber is fabricated and tested using outdoor solar vapor generation under direct solar radiation with an average solar intensity of 1.26 kW m−2. The solar absorber incorporated with hydrochar is derived at 250 °C for 3 h and displays the best average efficiency (71.35 ± 0.90%) and evaporation rate (1.30 ± 0.04 kg m−2 h−1). The collected clean water salinity (below 300 ppm) and pH (6.72–7.23) from the solar absorber is within the safe drinking water limit by the World Health Organization. Therefore, the hydrochar‐based solar absorber can be used to generate clean water from seawater desalination using solar vapor generation. [ABSTRACT FROM AUTHOR]

In this demonstrated design, we built a perfect solar absorber, with three appropriate layers of base (tungsten) layer, substrate (aluminum), layer, and gold resonator in a cross-design. The absorption result of the demonstrated cross-design can be identified in three sections by dividing the whole wavelength range (2800 nm) into two sections the first 1400-nm bandwidth range (starting from 0.2 to 1.6 µm), and the second part of 1400 nm (between 1.6 and 3 µm) respectively. With the support of the adding graphene layer by developing the top and middle layer, the absorption percentage can be increased to 91% for the overall range of 0.2 and 3 µm. The developed cross-design absorption rate is above 90% at an overall bandwidth of 2800 nm. For the first half section of the 1400-nm bandwidth (0.2–1.6 µm), the absorption amount is observed more than 90%, and at the rest half of the overall wavelength (1.6–3 µm), the solar radiation is greater than 95%. To highlight the variation in absorption situations, the peak four wavelengths (micrometers) are picked up such as λ1 = 0.33, λ2 = 1.23, λ3 = 2.24, and λ4 = 2.6 respectively. In this developed cross-solar design, the absorber can be explored in the four spectra of ultraviolet (UV) region, violet (V), and near and middle infrared regions (NIR and MIR). The creation of the cross-design in many steps, and it can be also expressed with the AM 1.5 situation. To indicate the absorption value variations for this cross design, various parameter sections of the ground layer parameter, cross design length, and substrate length can be distinguished in four different peak wavelengths. The electric potential value changes and the color distinguished of the electric field progression of the cross-design can be also extinguished. Transverse electric value and magnetic (TE and TM) variations in four different peak wavelengths can be demonstrated by varying degrees from 0 to 50. Finally, the proposed cross-design absorption value can be compared with the other published design in a table with the respective sections of absorption percentage, bandwidth range, angle variation, and polarization sensitivity respectively. [ABSTRACT FROM AUTHOR]

Early in history, societies utilize renewable energy sources in response to technical developments and external factors, which resulted in the development of hydropower, wind turbines, and solar PV, as well as their support through policies and agreements. The double ring covered disk resonator solar absorber (DRCDRSA) structures are examined over the spectral range of wavelength 0.2 µm to 2.5 µm (UV-FIR) with the help of finite element method (FEM) in this study. This design achieved effective solar absorption, surpassing 99% over the 0.46 µm band, 95% over 2.05 µm wideband, and 90% over the entire observed spectral range, with an overall average absorbance of 96.38%. In addition, the maximum absorbance is 99.9% with three pick values at the wavelengths of 0.34 µm, 1.35 µm, and 1.51 µm. This research includes a parameter optimization as well as the electric field strength and magnetic field intensity distribution over a three-dimensional solar absorber construction. The structure's angle-polarization study shows it is polarization independent, handles diverse angles, and maintains even absorption up to 60° across all wavelengths. This study explores effective solar heaters for air and water systems, offering promising prospects for maximizing solar energy utilization. [ABSTRACT FROM AUTHOR]

In this study, we propose a wide-angle broadband solar absorber based on multilayer etched toroidal structure. It is composed of a top layer Ti, W, and Si3N4 multilayer material, a silica insulator, and a Ti substrate. The average absorption from visible to mid-infrared wavelengths is 94.2%. The absorption bandwidth above 90% absorption is 3092 nm, and the peak absorption is 99.9%. The absorber achieves a perfect collection of incident solar energy caused by the combination of the local surface plasma resonance at the top layer of this absorber and the propagating plasma resonance in the lower insulator layer. The results are verified by applying impedance matching theory. Then, the effects of different structural geometrical parameters, polarization angles, and TE and TM incidence angles on the absorption are discussed. In addition, this absorber captures solar energy across the entire solar spectrum. Finally, we demonstrate that the absorber has a solar thermal conversion efficiency of more than 90% in the temperature range of 100–900 °C. This absorber has good application prospects in the fields of solar absorbers, solar thermal photovoltaic devices, and solar thermal electronic devices. [ABSTRACT FROM AUTHOR]

As part of this study, we elaborated and characterized samples of thin layers of cobalt oxide, doping them with different concentrations of nickel (2%, 4% and 6%). These films were deposited on ordinary glass substrates at a temperature of 400 °C, with a deposition time of 5 min, using the spray pyrolysis technique. The main objective of this research was to explore the influence of nickel doping on the physical properties of cobalt oxide. The results obtained by Raman spectroscopy confirmed the presence of Co+2 cations located in tetrahedral sites and Co+3 in octahedral sites, thus validating the spinel-type cubic structure. Morphological analysis revealed that the incorporation of nickel into the Co3O4 thin films, synthesized by spray pyrolysis, resulted in a significant transformation of the porous surface morphology. This transformation resulted in the transition from a porous structure to a dense and uniform configuration, characterized by nanoflower grains. Analyzes by EDS spectrometry revealed peaks associated with the elements Co and O, thus confirming the composition of the films. An improvement in the durability and overall performance of the solar device in humid environments by obtaining the hydrophobic character (CA = 99°) for the Co3O4/6%Ni film. The transmittance decreased with increased as a function of Ni concentration. Optical studies show direct band gaps Eg1 and Eg2 varying between 1.41 and 1.3 eV and between 2.09 and 1.99 eV respectively. Notably, the electrical resistivity experienced a significant decrease from 28.39 to 0.178 Ω.cm for the undoped and 2% Ni-doped films, respectively. However, for Ni concentrations ≥ 4%, the electrical resistivity increased from 3.47 to 10.2 Ω cm. [ABSTRACT FROM AUTHOR]

The increasing demand for renewable energy has increased in the last decade due to climate change resulting from conventional energy and solar cells become popular. The perfect absorption in solar cells can be achieved with artificially engineered materials at low cost for solar absorbers with high efficiency. A perfect ultra-broadband solar absorber can be achieved by using metamaterial (MM) based on surface plasmon resonance phenomena. We design a near-ideal ultra-broadband plasmonic MM absorber for solar energy harvesting over an ultra-broadband wavelength range (0.4–4 μ m ). The structure is made up of periodic taper arrays consisting of a thin, multilayered titanium nitride–titanium dioxide MM. The proposed structure has an absorption greater than 96% between the visible to infrared (IR) regime. It is independent of both polarization and incident angle. The large operational bandwidth, high absorption percentage, and compact thin structure combined with the strong thermal stability of metal TiN make an advantageous choice for solar thermophotovoltaics. [ABSTRACT FROM AUTHOR]

Industrial heat converters are essential to meet the growing demand for thermal energy in industries. This demand can be met by designing solar heat absorbers which can be used as renewable energy sources for these industries. The effective solar absorber is built with the efficient three layers of top and based layer is constructed with the titanium (Ti), and the middle layer is demonstrated with the Gallium Arsenide (GaAs). The resonator (Ti) layer is in the mathematical sign divide and the proposed design can be effectively explored in the four different infrared light regions. The second layer of the GaAs layer is sandwiched between the two Ti-based and resonator layers. In this divide sign solar absorber, the proposed resulting percentage can be identified by using the four peak wavelengths in micrometers of 0.45 for λ1, 0.8 for λ2, 2.2 for λ3, and 2.5 for λ4 respectively. The resulting absorption rate can be presented in three sections of 700 nm bandwidth is above 95% in that rate and the section of 710 nm bandwidth is above 90%. The overall accepted rate from 0.2 to the highest rate of 3 µm is 2800 nm and explores the average rate of greater than 90% (90.16%). The expression of the proposed divided sign solar absorber, the building section's multistep inclusions, and the Air Mass (AM)1.5 situation in the different color sections can also be approved. The different studies of the design section can be expressed by changing the Ti-based and resonator layers, GaAs middle layer. Moreover, the amount of chemical potential and the TE and TM difference can also be analyzed with the degree changes from 0 to 50 degrees. The proposed dividend solar design can be used as a heat converter in industries as effective renewable energy such as cooling techniques, oil refining, recovery systems, air conditioning.

This study investigates the process of using multi-walled carbon nanotube (MWCNT) coatings to enhance lamp heating temperatures for solar thermal absorption applications. The primary focus is studying the effects of the self-organized honeycomb structures of CNTs formed on silicon substrates on different cell area ratios (CARs). The drop-casting process was used to develop honeycomb-structured MWCNT-coated absorbers with varying CAR values ranging from ~60% to 17%. The optical properties were investigated within the visible (400–800 nm) and near-infrared (934–1651 nm) wavelength ranges. Although fully coated MWCNT absorbers showed the lowest reflectance, honeycomb structures with a ~17% CAR achieved high-temperature absorption. These structures maintained 8.4% reflectance at 550 nm, but their infrared reflection dramatically increased to 80.5% at 1321 nm. The solar thermal performance was assessed throughout a range of irradiance intensities, from 0.04 W/cm2 to 0.39 W/cm2. The honeycomb structure with a ~17% CAR value consistently performed better than the other structures by reaching the highest absorption temperatures (ranging from 52.5 °C to 285.5 °C) across all measured intensities. A direct correlation was observed between the reflection ratio (visible: 550 nm/infrared: 1321 nm) and the temperature absorption efficiency, where lower reflection ratios were associated with higher temperature absorption. This study highlights the significant potential for the large-scale production of cost-effective solar thermal absorbers through the application of optimized honeycomb-structured absorbers coated with MWCNTs. These contributions enhance solar energy efficiency for applications in water heating and purification, thereby promoting sustainable development.

This work presents an ultra-broadband metamaterial absorber in the wavelength range of 250–4000 nm. The absorber consists of a Ti disk resonator and a stack of TiO2/Ti square-shaped resonators, supported by TiO2/Ti thin layers. This arrangement of the layers offers a metal–insulator-metal configuration, enhancing the absorptivity of the structure. The effects of geometrical parameters, including the thickness of the resonators, the radius of the disk resonators, and the width of the square resonator, on the absorption spectrum of the absorber are investigated. To attain the highest average absorption, the particle swarm optimization (PSO) algorithm is employed. The simulation results obtained by the finite-difference time-domain method indicate that the average absorption can reach a high value of 96.25% over the studied wavelength range. The over 90% absorption bandwidth is 3509 nm. Additionally, the solar absorption of the absorber is 94.89%. The absorption is more than 80% even for incident angles up to 50° for both TM and TE polarizations. The proposed absorber is a very promising option for solar energy harvesting, photo-thermal technology, photo-detection, and thermal-photovoltaics applications due to its high over 90% bandwidth, independence on the polarization and angle of incident light, and ease of fabrication. [ABSTRACT FROM AUTHOR]

Energy harvesting is renowned in the past flue decades, and renewable energy is the superlative cause of the energy. Researchers investigated many surface plasmon resonance structures for the same, but the materials they have used prevent more losses. In this work, graphite, Al2O3, ZrO2, and TiO2 are used in order to gather greater amounts of sunlight. The Sharp Triangular Structure — Ring (STSR) Shape has been created using various lithography techniques to increase absorptance and obtain 95.35% of the solar spectrum (0.2–2.5-µm wavelength) to get the greatest results with these materials. The structure's absorption rates for the UV, VIS, and IR regions are 97.49, 96.28, and 94.99%, respectively. The role of the resonator is also explained in this study with magnetic and electric field norms. The graphite substrate has an absorptance of 67.63%, a reflectance of 32.20%, and a transmittance of 1.39%. Applying the resonator causes a reduction in reflectance of up to 27.82% and results in 95.35% absorptance. It could function as a radiation barrier, solar induction heater for water and air, and many other things. It is applicable in space missions and satellite since it can capture the majority of the radiation from space. [ABSTRACT FROM AUTHOR]

We have designed a multilayered solar absorber composed of several materials, including tungsten, magnesium fluoride, MXene, silicon, and silver. The structural frame is composed of a resonator constructed from silver (Ag) in the form of Jerusalem. The absorption results are compared with the traditional AM 1.5 data, and the finite element method computational tools are used to analyse the structure of the absorber to investigate the many physical elements that contribute to changes in absorption. Except for the resonator height, this design demonstrates the least amount of variation in absorption when considering all physical characteristics. Hence, the resonator's height is one of the most critical aspects in deciding the final output. The solar absorber achieves constant absorption values for a large incidence angle range (80°). We have also used a prediction model based on the findings of our computational analysis. We used an ANN prediction model for the suggested prediction design, and the results for the 2500 epoch data set were impressive with values of different parameters RMSE = 0.029, MAE = 0.020, MSE = 0.0013, and R2 = 0.96. The accurate model developed in this work may be used to predict the absorption levels for various values of the structure's physical properties. Solar absorber structure design for infrared, visible, and UV light absorption is made easier with the help of the provided findings and predicted model. [ABSTRACT FROM AUTHOR]

This paper proposes a single-band three-layer solar cell energy harvesting absorber that is insensitive to polarization. It uses a Stepped impedance-based metamaterial (SIR-MM) structure to absorb light in the visible range (450THz to 750 THz). The substrate is made of durable silicon, with a gallium arsenide semiconductor layer and a tungsten-based conducting metamaterial layer on top. The Step Impedance Resonator-based metamaterial absorber sustains absorption above 80% in the frequency range of 477 THz to 631 THz and can achieve over 90% absorption in the visible spectrum (490 THz to 610 THz). The proposed metamaterial structure is analyzed with different materials, and the absorption curve remains insensitive to the incident angle. The SIR-MM absorber is designed for high-efficiency solar cell energy harvesting applications, with optimized S21 and S11 characteristics. From the analysis, the proposed SIR-MM absorber is designed for the optimum value and it worked best for high-efficiency solar cell energy harvesting applications. [ABSTRACT FROM AUTHOR]

Industrial heat converters are essential to meet the growing demand for thermal energy in industries. This demand can be met by designing solar heat absorbers which can be used as renewable energy sources for these industries. The effective solar absorber is built with the efficient three layers of top and based layer is constructed with the titanium (Ti), and the middle layer is demonstrated with the Gallium Arsenide (GaAs). The resonator (Ti) layer is in the mathematical sign divide and the proposed design can be effectively explored in the four different infrared light regions. The second layer of the GaAs layer is sandwiched between the two Ti-based and resonator layers. In this divide sign solar absorber, the proposed resulting percentage can be identified by using the four peak wavelengths in micrometers of 0.45 for λ 1, 0.8 for λ 2, 2.2 for λ 3, and 2.5 for λ 4 respectively. The resulting absorption rate can be presented in three sections of 700 nm bandwidth is above 95% in that rate and the section of 710 nm bandwidth is above 90%. The overall accepted rate from 0.2 to the highest rate of 3 µm is 2800 nm and explores the average rate of greater than 90% (90.16%). The expression of the proposed divided sign solar absorber, the building section's multistep inclusions, and the Air Mass (AM)1.5 situation in the different color sections can also be approved. The different studies of the design section can be expressed by changing the Ti-based and resonator layers, GaAs middle layer. Moreover, the amount of chemical potential and the TE and TM difference can also be analyzed with the degree changes from 0 to 50 degrees. The proposed dividend solar design can be used as a heat converter in industries as effective renewable energy such as cooling techniques, oil refining, recovery systems, air conditioning. [ABSTRACT FROM AUTHOR]

The selective broadband absorption of solar radiation plays a crucial role in applying solar energy. However, despite being a decade-old technology, the rapid and precise designs of selective absorbers spanning from the solar spectrum to the infrared region remain a significant challenge. This work develops a high-performance design paradigm that combines deep learning and multi-objective double annealing algorithms to optimize multilayer nanostructures for maximizing solar spectral absorption and minimum infrared radiation. Based on deep learning design, we experimentally fabricate the designed absorber and demonstrate its photothermal effect under sunlight. The absorber exhibits exceptional absorption in the solar spectrum (calculated/measured = 0.98/0.94) and low average emissivity in the infrared region (calculated/measured = 0.08/0.19). This absorber has the potential to result in annual energy savings of up to 1743 kW h/m2 in areas with abundant solar radiation resources. Our study opens a powerful design method to study solar-thermal energy harvesting and manipulation, which will facilitate for their broad applications in other engineering applications.

A U-shaped Metal-Insulator-Metal (MIM) solar energy absorber is simulated, and designed in this paper. Tungsten is utilized as the base metal layer because of its transmission blocking characteristics, the SiO2 is used as a dielectric insulator and a U-shaped resonator made of titanium as a radiation absorber to achieve a near perfect Solar energy absorber as it provides the impedance matching abilities. The proposed structure is simulated over the solar spectrum which covers the wavelengths from 0.2 to 2.5 µm which includes the ultraviolet (UV) to near infrared (NIR) bands, the absorbed energy is of 94.52%, 97.06%, and 96.67%, respectively. Furthermore, the additional investigation under solar radiation is conducted and the proposed structure is absorbing most of the energy while the minimal amount is missed in visible range. The main contribution of this work lies in its broadband absorption spectrum which is achieved employing a very simple and easy to fabricate structure. In addition, the structure also achieves the angle and polarization insensitiveness. The major contribution is the prediction of absorption at an intermediate wavelengths with locally weighted linear regression with a R2 score of 0.9999. The proposed structure can be used for the efficiency enhancement of thermoelectric photovoltaic devices.

Thermal energy harvesting has seen a rise in popularity in recent years due to its potential to generate renewable energy from the sun. One of the key components of this process is the solar absorber, which is responsible for converting solar radiation into thermal energy. In this paper, a smart performance optimization of energy efficient solar absorber for thermal energy harvesting is proposed for modern industrial environments using solar deep learning model. In this model, data is collected from multiple sensors over time that measure various environmental factors such as temperature, humidity, wind speed, atmospheric pressure, and solar radiation. This data is then used to train a machine learning algorithm to make predictions on how much thermal energy can be harvested from a particular panel or system. In a computational range, the proposed solar deep learning model (SDLM) reached 83.22 % of testing and 91.72 % of training results of false positive absorption rate, 69.88 % of testing and 81.48 % of training results of false absorption discovery rate, 81.40 % of testing and 72.08 % of training results of false absorption omission rate, 75.04 % of testing and 73.19 % of training results of absorbance prevalence threshold, and 90.81 % of testing and 78.09 % of training results of critical success index. The model also incorporates components such as insulation and orientation to further improve its accuracy in predicting the amount of thermal energy that can be harvested. Solar absorbers are used in industrial environments to absorb the sun’s radiation and turn it into thermal energy. This thermal energy can then be used to power things such as heating and cooling systems, air compressors, and even some types of manufacturing operations. By using a solar deep learning model, businesses can accurately predict how much thermal energy can be harvested from a particular solar absorber before making an investment in a system.

Disordered ridge-splitting on laser-induced periodic surface structures (LIPSSs) often reduces structure quality and degrades application performance but introduces a potential route for laser structuring accuracy with access to the deep-subwavelength scale. Here, nanolithography based on the homogeneous ridge-splitting mechanism is implemented on a molybdenum surface using two-color (400 and 800 nm) temporally delayed femtosecond laser pulses with identical linear polarizations. The achieved splitting LIPSS, with a periodicity down to 140 nm and a feature size down to 70 nm, was uniformly distributed in the long range without any wavy or interruption defects, presenting improvements on the structure's accuracy and quality relative to the observation of single-beam femtosecond 400 nm laser irradiation. The generation and suppression of the homogeneous ridge-splitting phenomenon can be manipulated via altering the time delay or the fluences of the two-color laser pulses, which results in transitions between the regular near-subwavelength and deep-subwavelength LIPSSs. The underlying physical origins are attributed to the excitation of various electromagnetic field enhancement modes during the transiently correlated dynamic process of two-color laser–material interactions. Our investigations facilitate the laser nanostructuring of metals with an accessible 100 nm feature size, and the nanostructured Mo surface enables specific applications in the field of concentrated solar energy devices. [ABSTRACT FROM AUTHOR]

This article details the development of an MXene-based fractal metamaterial solar absorber (MMA) that operates in the visible and near-infrared ranges. A silicon dioxide (SiO2) substrate, a silver reflecting surface, and a single sheet of fractal pattern MXene make up the suggested absorber. With a normal incidence spectrum from 400 to 1500 nm, this dual-band absorber has an absorptivity over 80%. In addition, its narrow band absorption peak with 100% absorptivity in the visible range demonstrates its value for sensing applications. The suggested metasurface's electric resonance is responsible for its impressive absorption throughout a large portion of the spectrum, from the visible to the near-infrared. In addition, the suggested solar absorber's polarization insensitivity originates from the symmetric fractal structure. Experiments have shown that the angle of light's incidence has no effect on the absorber. The suggested absorber's strong narrow-band absorption in the visible range may be beneficial for sensing applications, and its wide-band absorption in the near-infrared area may improve light-to-heat conversion, both of which would benefit solar energy systems. [ABSTRACT FROM AUTHOR]

Solar-based desalination is one of the sustainable methods of obtaining clean water from contaminated water. Recent advances in the production of highly efficient photothermal absorbers have increased their evaporation rate. Improved solar absorption (> 94%) and lowered heat loss are two distinct advantages over traditional solar desalination systems (TSDS). This review emphasizes the novelty of exploring waste materials, cost-effectiveness, and their potential for reuse in solar desalination. The focus is primarily on waste materials derived from (i) urban/residential sources, (ii) plant-based biochar, and (iii) ocean-derived biomass. By incorporating these waste materials into the process, we aim to enhance sustainability, reduce environmental impact, and promote the efficient utilization of resources in this emerging field. Furthermore, the results on evaporation rate, photothermal efficiency, productivity of the absorbers under practical conditions and their durability, economic feasibility, desalination performance for wastewater, methods for increasing freshwater productivity, and future prospects are discussed. The CI/CS hydrogel synthesized from cuttlefish produces at a maximal rate of 4.1 kg m−2 h−1 under artificial sun illumination. The CNT-coated Juncus effuses absorber produces 20.3 L/day under natural solar irradiation. In traditional solar desalination systems, the freshwater productivity of 5.9 L/m2.day was achieved with waste wicks and a solar collector. It shows that adequate freshwater production in TSDS requires a second thermal energy source, such as a phase change material (PCM) or solar collector. [ABSTRACT FROM AUTHOR]

Tapping the potential of solar thermal energy requires spectrally selective solar absorber coatings, which lead to high photothermal efficiency. Micro‐cavities are known to dramatically enhance or suppress light absorption and emission in a directional manner and are used in nanophotonics, photodetectors, lasing, etc. Here, a dielectric‐metal‐dielectric multilayer stack with an optical micro‐cavity of a 12 nm tungsten layer formed between two dielectric layers of transition metal oxide CuCo2O4 (CCO) is designed. The CCO‐W‐CCO thin film multilayers deposited on stainless steel substrate by DC‐radio frequency magnetron sputtering achieve a 90% solar absorptance for the entire solar spectrum and a thermal emittance of 19% for the infrared spectrum. Optimization of thicknesses of individual layers is achieved by numerical simulations done in COMSOL Multiphysics, thereby reproducing the optical properties of each layer. The simulation results satisfactorily reproduce the experimental reflectance and demonstrate maximum power dissipation in the metallic layer in visible as well as NIR regions. Nevertheless, CCO material characterizations reveal that the enhanced absorption over the entire solar spectrum could be attributed to the underlying spinel crystal structure and the nanostructure film morphology. [ABSTRACT FROM AUTHOR]

Solar absorber, which effectively collects solar energy and converts it into thermal energy, is the essential component of a solar thermal system such as concentrated solar power, thermophotovoltaic systems. However, most highly efficient solar absorbers require expensive lithographic techniques to implement. Therefore, in this work, we propose a lithography-free multilayer W/SiO2 solar absorber for efficient photothermal conversion. The solar absorption characteristics of the absorber in the full spectral range are investigated concerning the incidence, polarization angle, geometry parameters, and the number of cells. The results show that the absorber can achieve a total solar absorption efficiency of 97.17%, exhibiting polarization insensitivity and wide-angle characteristics. The absorption mechanism can be explained by superimposed Fabry–Perot resonance, confirmed by the electric field and normalized power dissipation density distributions. In addition, the absorber can achieve a photothermal conversion of up to 90.02% at 100℃ without considering the solar concentration factor. Finally, we investigated the variation of photothermal conversion efficiency with temperature for different solar concentration factors. The research shows that increasing the solar concentration factor is beneficial for improving the photothermal conversion of the absorber in high-temperature environments. This work may provide a valuable guide for the design of lithography-free solar absorbers. [ABSTRACT FROM AUTHOR]

Solar absorbers are of great significance in the development of new energy technologies. However, the current approaches are mostly complex and fail to achieve high absorption rates across a wide range of wavelengths. Here, we propose a four-step stacked metamaterial solar absorber that achieves near-perfect absorption. Our four-step stacked absorber (FSSA) boasts an average absorption rate of 96.32% from 499 nm to 2348.3 nm, and a high average absorption rate of 94.96% from 300 nm to 2500 nm. Electromagnetic mode analysis and the impedance matching theory were employed to analyze the designed FSSA, which revealed that the high absorption rates are due to the propagating surface plasmon resonance (PSPR) and localized surface plasmon resonance (LSPR) modes. The FSSA offers broadband, high absorption rates, and high spectrum selectivity. Additionally, the structural parameters are adjusted to optimize the proposed perfect solar absorber. This proposed absorber can have promising applications in the renewable energy industry. [ABSTRACT FROM AUTHOR]

In this work, the structural polymorphism and electro-optical characteristics of NaSbS2 ternary chalcogenide are realized using density functional theory (DFT). All of the NaSbS2 polymorphs are energetically stable based on the formation energy. The optimized lattice parameters of the monoclinic and triclinic structures and direct electronic bandgap (1.695 eV) of monoclinic structure are consistent with previous studies. Besides, the trigonal and triclinic structures are indirect bandgap (0.916 and 2.015 eV) semiconductors observed from electronic band structure. The higher degree of ionicity between Na and S atoms while strong covalency in the Sb-S bonds are confirmed from the charge and bond analysis. The lower value of electron-hole effective masses indicates higher carrier mobility leading to outstanding electrical conductivity. It was suggested that the polymorphs would be extremely desired to design Bragg reflectors and waveguides based on the reported high value of the real part of the dielectric constant and refractive index. These polymorphs will contribute significantly to being used as absorbers, as evidenced by their high absorption coefficient and photoconductivity and lower transmittance. All the polymorphs reflect significant optical anisotropy and birefringence, rendering them excellent for usage in the fabrication of waveguides, polarizers, and photonic devices. Thus, the projected good features of NaSbS2 polymorphs would play an essential role in the development of lead-free photovoltaic devices, including solar cells and other optoelectronic devices, and would be able to provide practical information for future theoretical and experimental studies.

Solar vapor generation is a promising clean water generation as it utilizes clean and renewable solar energy as the energy source, along with the use of low-cost and sustainable carbonized sawdust (CSD). In this work, CSD coated cotton towel was used as the solar absorber (SA) for seawater desalination by solar vapor generation. A series of different weight percentage solar absorber was fabricated for the determination of the optimal photothermal conversion material content. The experiment was conducted by outdoors solar vapor generation using deionized water. The best performed 60 wt% CSD coated cotton towel solar absorber (SA60) was chosen for the seawater desalination towards clean water generation. Outdoors solar vapor generation was conducted for about 2 h with seawater gathered from the beach coast of Universiti Malaysia Sabah. Average efficiency of SA60 was calculated at 63.41 ± 1.31% with the average evaporation rate at about 1.15 kg/m2 h. Salinity (120 ppm) and pH (7.22) of the collected clean water was within the World Health Organization safe water limit standard. [ABSTRACT FROM AUTHOR]

This study experimentally demonstrates two types of ultra-broadband metamaterial absorbers with high performance in the visible-to-near-infrared range by using different anti-reflection coatings (i.e., SiO2 and Si3N4) and a multi-subcell Ti-SiO2-Ti metasurface. Compared to the bare metamaterial nanostructure, the absorption bandwidth of the coated metasurfaces exhibit increases of 594 nm and 1093 nm, respectively. Such improvements benefit from nearly perfect impedance matching to the free space enhanced by the anti-reflection coating, thin film interference, and excitations of different surface plasmon resonances. As a result, the absorber with SiO2 coating exhibits a measured bandwidth with an absorption of 0.9 ranging from 502 nm to 1892 nm, while the absorber with Si3N4 coating further broadens the bandwidth from 561 nm to 2450 nm. The measured average absorptions for both cases remain above 95% and 87%, respectively. Moreover, both nanostructures are robust to large incident angles of up to 60° for both TE and TM modes. Our findings highlight the promising potential of these absorbers for various applications, including solar energy harvesting, thermal emitters, and photodetectors. [ABSTRACT FROM AUTHOR]

The increased demand for solar energy-based applications including photovoltaics, thermophotovoltaics, and other solar harvesting devices has generated a high demand for solar absorbers absorbing solar energy over the whole solar spectrum compared to the largely available narrowband and multiband solar absorbers. A solar absorber using a slotted resonator of Zirconium (Zr) over the Titanium (Ti) ground plane is presented. The proposed structure is analyzed in the 0.5–3 µm bandwidth to study its absorptance characteristics and ideal properties by analyzing the characteristics of absorptance, transmittance, reflectance, and electric field scattering, absorptance under solar radiation, different polarization, and angle of incidences. The absorptance values of 99%, 97.23%, 95%, 96%, 96%, and 96% are observed at 0.52 µm, 0.82 µm, 1.2 µm, 1.63 µm, 2.09 µm, and 2.65 µm, sequentially. The overall 2450 nm bandwidth is observed with 90% absorption and the 1260 nm bandwidth is observed with 95% absorption. The simulation results demonstrate six near-unity absorptance modes. The absorptance bandwidth spectrum is optimized by varying the parameter of the proposed structure. In addition, the solar absorber achieved the best angle of incidence insensitivity for Transverse Electric (TE) and Transverse Magnetic (TM) polarizations modes. The proposed absorber with its high performance which is compared with available broadband absorbers to show its higher performance can be applied for a vast range of applications related to solar energy harvesting. [ABSTRACT FROM AUTHOR]

Energy-efficient buildings are a new demand in the current era. In this paper, we present a novel metamaterial design aimed at achieving efficient solar energy absorption through a periodic MMA structure composed of a W-GaAs-W. The proposed structure can be implemented as the window coating and in turn it can absorb the incident solar energy and, then, this energy can be used to fulfill the energy demand of the building. Our results reveal significant improvements, achieving an average absorptance of 96.94% in the spectral range. Furthermore, we explore the influence of the angle of incidence on the absorber's response, demonstrating its angle-insensitive behavior with high absorption levels (above 90%) for incidence angles up to 60° for TE polarization and 40° for TM polarization. The proposed structure presents a significant advancement in metamaterial-based solar energy absorption. By exploring the effects of structural parameters and incident angles, we have demonstrated the optimized version of our proposed absorber. The potential applications of this metamaterial absorber in self-sufficient futuristic building technologies and self-sustaining systems offer new opportunities for harnessing solar energy and are a valuable contribution to future developments in the fields of metamaterials and renewable energy. [ABSTRACT FROM AUTHOR]

Since the use of chemical fuels is permanently damaging the environment, the need for new energy sources is urgent for mankind. Given that solar energy is a clean and sustainable energy source, this study investigates and proposes a six-layer composite ultra-wideband high-efficiency solar absorber with an annular microstructure. It achieves this by using a combination of the properties of metamaterials and the quantum confinement effects of semiconductor materials. The substrate is W–Ti–Al2O3, and the microstructure is an annular InAs-square InAs film–Ti film combination. We used Lumerical Solutions' FDTD solution program to simulate the absorber and calculate the model's absorption, field distribution, and thermal radiation efficiency (when it is used as a thermal emitter), and further explored the physical mechanism of the model's ultra-broadband absorption. Our model has an average absorption of 95.80% in the 283–3615 nm band, 95.66% in the 280–4000 nm band, and a weighted average absorption efficiency of 95.78% under AM1.5 illumination. Meanwhile, the reflectance of the model in the 5586–20,000 nm band is all higher than 80%, with an average reflectance of 94.52%, which has a good thermal infrared suppression performance. It is 95.42% under thermal radiation at 1000 K. It has outstanding performance when employed as a thermal emitter as well. Additionally, simulation results show that the absorber has good polarization and incidence angle insensitivity. The model may be applied to photodetection, thermophotovoltaics, bio-detection, imaging, thermal ion emission, and solar water evaporation for water purification. [ABSTRACT FROM AUTHOR]

A U-shaped Metal-Insulator-Metal (MIM) solar energy absorber is simulated, and designed in this paper. Tungsten is utilized as the base metal layer because of its transmission blocking characteristics, the SiO 2 is used as a dielectric insulator and a U-shaped resonator made of titanium as a radiation absorber to achieve a near perfect Solar energy absorber as it provides the impedance matching abilities. The proposed structure is simulated over the solar spectrum which covers the wavelengths from 0.2 to 2.5 µm which includes the ultraviolet (UV) to near infrared (NIR) bands, the absorbed energy is of 94.52%, 97.06%, and 96.67%, respectively. Furthermore, the additional investigation under solar radiation is conducted and the proposed structure is absorbing most of the energy while the minimal amount is missed in visible range. The main contribution of this work lies in its broadband absorption spectrum which is achieved employing a very simple and easy to fabricate structure. In addition, the structure also achieves the angle and polarization insensitiveness. The major contribution is the prediction of absorption at an intermediate wavelengths with locally weighted linear regression with a R2 score of 0.9999. The proposed structure can be used for the efficiency enhancement of thermoelectric photovoltaic devices. [ABSTRACT FROM AUTHOR]

In parabolic trough technology, the development of thermally and structurally stable solar coatings plays a key role in determining the efficiency, durability, and economic feasibility of tube receivers. A cermet-based solar coating is typically constituted by a thin film stratification, where a multilayer graded cermet is placed between an infrared metallic reflector and an antireflection filter. This work reports the realization of materials based on Al2O3 and W characterized by high structural and chemical stability in vacuum at high temperature, obtained through the optimization of high-deposition-rate processes. Al2O3 material, employed as the antireflection layer, was deposited through a reactive magnetron sputtering process at a high deposition rate. Cermet materials based on W-Al2O3 were deposited and employed as absorber layers by implementing reactive magnetron co-sputtering processes. An investigation into the stability of the realized samples was carried out by means of several material characterization methods before and after the annealing process in vacuum (1 × 10−3 Pa) at high temperature (620 °C). The structural properties of the samples were evaluated using Raman spectroscopy and XRD measurements, revealing a negligible presence of oxides that can compromise the structural stability. Spectrophotometric analysis showed little variations between the deposited and annealed samples, clearly indicating the high structural stability.