Robust Ultrablack Coating for Omnidirectional Broadband Light Absorption

The practical application of solar energy harvesting urgently calls for the facile preparation of high‐performance ultrablack surfaces with broadband and omnidirectional light absorption performance; however, some roadblocks still need to meet these requirements simultaneously. Herein, cone‐array ultrablack (CAUB) surfaces are prepared by combining feasible template replication and blade coating techniques. The elaborate micro‐sized cone structure and high absorptive materials (polydimethylsiloxane@carbon black, PDMS@CB) offer the CAUB extremely high, broadband, and omnidirectional light absorption over the solar spectrum with an average absorbance of 99.35%. Under one sun irradiation, the CAUB can efficiently absorb solar energy, reaching a surface temperature as high as 75 °C. A solar‐thermal‐electric generator (STEG) made from the CAUB film demonstrates real‐time solar‐heat‐electric conversion, achieving a high output power density of 330 µW cm−2. The CAUB film possesses excellent water repellency, flexibility, chemical solvent resistance, and potential for large‐scale production, satisfying the application requirements of solar energy harvesting and utilization.

To improve EUV resist sensitivity, studies have sought to enhance EUV light absorption by adding metals characterized by high EUV light absorption to the resist polymer. This approach is intended to increase secondary electron emission, thereby enhancing PAG reactivity and improving acid generation efficiency [1-3]. As reported in our previous report, to determine whether adding metals characterized by high EUV light absorption actually enhances sensitivity, we performed transmittance measurements and sensitivity evaluations of resist samples doped with ZrO2 or TeO2 nanoparticles, which have low and high EUV light absorption, respectively, in molar quantities of 0-2 relative to PAG. The samples were subjected to EUV exposure at the NewSUBARU synchrotron radiation facility. The results of transmittance measurements and sensitivity evaluations showed that, while the ZrO2-doped resist showed no changes in absorption or sensitivity, the TeO2-doped resist showed enhancement in both properties. Based on these results, we confirmed that adding metals characterized by high EUV light absorption to the EUV resist enhances its EUV light absorption and increases secondary electron emission, thereby enhancing PAG reactivity and improving acid generation efficiency [4-5]. In the efforts discussed in the present report, we examined whether adding metals directly to PAG could further enhance sensitivity by increasing the EUV light absorption of PAG itself, thereby efficiently heightening the effect of the secondary electron emission on PAG.

We have carried out extensive investigations of the gas phase composition during diamond CVD in a conventional hydrogen rich environment. Absolute densities of CH/sub 3/, CH, and the hydrogen dissociation ratio have been measured in hydrocarbon-based plasma-enhanced CVD (PECVD) and hot filament CVD (HFCVD) environments. Additional species, C/sub 2/H/sub 2/ and C/sub 6/H/sub 6/ have been studied in hot filament activated diamond growth. High sensitivity white light absorption spectroscopy has been able to provide a quantitative description of the densities of all the single carbon hydrocarbon species in hydrogen-rich diamond growth. The most extensively studied species is the CH/sub 3/ radical. This radical is the key to the diamond growth mechanism in hydrogen-rich diamond CVD. As with many other polyatomic species, the excited electronic levels of CH/sub 3/ all dissociate. Consequently, laser-induced fluorescence measurements are not possible with this species. Prior to the work with high sensitivity white light absorption spectroscopy, the CH/sub 3/ radical had been detected using resonantly-enhanced multiphoton ionization (REMPI), infrared diode laser absorption and near threshold ionization mass spectrometry. Compared with these techniques, high sensitivity white light absorption spectroscopy is considerably simpler and more sensitive, even deep in the ultraviolet.

This study analyzed the electronic and optical properties of pentacene derivatives chemically modified by adding nitro and amine groups at different positions on the molecular structure. The study aimed to understand the impact of these modifications on electronic and optical applications, focusing on improving performance in organic electronic devices and solar cells. The results showed that adding nitro groups as electron acceptors and amine groups as electron donors reduces the energy gap and increases the chemical activity of the molecules. It was also observed that changing the positions of these groups significantly affects the polar moment, reflecting changes in the charge distribution within the molecules. In terms of optical properties, the modified molecules showed high light absorption in the visible region of the electromagnetic spectrum, making them promising candidates for organic solar cell applications, where high light absorption efficiency is a prerequisite for these applications. All calculations were performed using the Gaussian 09 software package. The study included molecular geometry optimization using density functional theory (DFT) with the B3LYP hybrid functional and 6-31G(d,p) basis set. Electronic properties, such as the highest occupied molecular orbital HOMO and lowest unoccupied molecular orbital LUMO energy levels, and the energy gap between them were calculated to evaluate the stability and chemical activity. Time-dependent density functional theory (TD-DFT) was used to analyze the optical properties and light absorption. In addition, fixed points were confirmed by vibrational frequency analysis to ensure that the optimized molecular structures represent stable states. The study also included a polar moment calculation to evaluate the effect of chemical modifications on the polarity of the molecules.

Transition metal dichalcogenides (TMDCs) have been proposed as light absorber materials for ultrathin solar cells. These materials are characterized by their strong light-matter interaction and the possibility to be assembled into devices at room temperature. Here, we model the optical absorptance of an ultrathin MoS2 absorber embedded in different designs of a 1D optical cavity. We find that up to 87% of the photons contained in the 300-700 nm range of the AM1.5G spectrum can be absorbed employing MoS2 absorbers as thin as 10 nm sandwiched between a h-BN top layer and an optically thick Ag reflector. An h-BN/MoS2/h-BN/Ag cavity produces 0.89 average absorptance for a 57-nm-thick MoS2 slab and it also maximizes the absorption of extremely thin absorbers, between 1 and 9 nm. We also model a possible large-scale device on a glass substrate combined with indium-tin oxide (ITO) whose absorptance is comparable to the other presented structures. The high broadband absorption in these light-trapping structures is caused by the amplification of the zeroth Fabry-Perot interference mode. This study demonstrates that light absorption in ultrathin solar cells based on nanometric TMDC absorbers can compete with conventional photovoltaic technology and provides different simple optical designs to choose from depending on the electronic characteristics of the TMDC junction.

Graphene-CoO/PEG composite phase change materials with enhanced solar-to-thermal energy conversion and storage capacity

Enhanced solar thermal conversion and thermal conduction of MWCNT-SiO2/Ag binary nanofluids

Solar energy is an abundant renewable source of energy for seawater desalination. Interfacial solar water evaporation technology based on photothermal processes is one of the most effective ways of utilizing solar energy. However, practical challenges such as low efficiency, complexity, and poor durability, have hindered the widespread adoption of this technology. To tackle these challenges, research has been focused on developing materials that exhibit broad-spectrum light absorption, high mechanical and thermal stability, and low thermal conductivity. Moreover, growing waste from high-performance materials such as aramid fibers and carbon fibers highlights the need for sustainable practices, such as upcycling these fibers instead of relying on new resources. In this study, we have demonstrated the upcycling of waste aramid fibers and carbon fibers into aerogels for water evaporators. The incorporation of MXene into the aerogels has significantly enhanced light absorption compared to both ANF and ANF-CF aerogels. This improvement, along with increased photothermal efficiency and hydrophilicity, led to an optimized structure with a solar-to-vapor conversion efficiency of 103.6 % and an evaporation rate of 1.63 kg m⁻2 h⁻1 under one sun. The MXene/aramid fiber/carbon fiber aerogels, with their three-dimensional structure, provided the foundation for the development of stable solar interfacial evaporators that could efficiently convert seawater into clean drinking water through high light absorption and mechanical stability.

Highly stable, easily regenerable photothermal porous black ceramics used in an energy-efficient bionic system for practical solar-driven interfacial evaporation

Ultrablack materials have excellent light absorption properties and are widely used in modern scientific and technological fields such as precision optics, aerospace, energy, and biomedicine. Current methods, such as sol-gel methods and nanoimprint lithography, can achieve high uniformity and nanostructure control of thin film materials, but the preparation process is complex, involving high-purity precursors and a variety of chemical materials. Additionally, the prepared materials have issues with mechanical stability and weather resistance. Here, this study proposes the use of ion-source-assisted deposition (IAD) to prepare NbOx multilayer ultrablack films with high light absorption and environmental stability. The composite structure of the multilayer ultrablack film consists of a NbOx absorption layer and a multilayer anti-reflective film. This film by IAD at 300°C exhibits an average reflectance of 0.68% and an absorption rate of 99.29% in the spectral range of 400-1000nm. While the average reflectance is 0.75% and absorption is 99.07% at room temperature. In comparison, the films prepared under 300°C are more suitable for high-temperature resistant substrates, and the room temperature deposition is more suitable for non-high-temperature resistant substrates. Moreover, the NbOx ultrablack absorbing film also exhibits excellent mechanical stability and weather resistance and successfully passes reliability testing, including grid testing, abrasion resistance testing, and water boiling testing, which are required for industrial applications. This study offers a viable solution for the low-cost and large-scale industrial application of ultrablack thin films, with 99.29% absorption rate and 0.68% reflectivity.

Structure and properties of carboxymethyl cotton fabric loaded by reduced graphene oxide

The indium gallium nitride (InGaN) ternary alloy system offers an ideal semiconductor basis as a light absorber for driving chemical reactions such as the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). It is a direct bandgap semiconductor whose energy can be tuned for optimal solar absorption and overcoming kinetic overpotential losses, it can be grown epitaxially as a single crystal for high material quality, and it exhibits relatively high corrosion resistance in aqueous solutions for a III-V material. In this work, we report on the design, synthesis, and photoelectrochemical studies of InGaN in an anode configuration with a goal of using this material as a light absorber basis for driving solar fuels reactions such as the OER and the HER. Studies are shown reporting on how reactive vapor synthesis of GaN and InN with different structuring affects the light conversion properties and band diagram electrostatics in an electrochemical junction with ferrocene and cobaltocene redox pairs. This structure is extended to thin films of GaN and InGaN grown by molecular beam epitaxy for high efficiency light conversion, with the resulting electrochemical junction also made with ferrocene and cobaltocene. The effects of ternary alloying, doping, and the two different c-plane polarities (III-polar and V-polar) on the junction are investigated using the same electrochemical junction to evaluate the light conversion properties in relation to the electrostatics; specifically, tuning the bandgap energy for optimal light absorption, determining the c-plane polarity configuration for the electric fields to have the correct band alignment, and incorporating silicon doping to create a conductive substrate. The combination of these engineering techniques extends the depletion region of the active layer for high efficiency light absorption as similarly demonstrated for epitaxial phosphide films [1], and is utilized toward the goal of high performance solar energy conversion. [1] V. Parameshwaran, X. Xu, and B. Clemens, Journal of the Electrochemical Society, vol. 163, no. 8, pg. H714-H721 (2016).

This study identifies the characteristics of water regions with negative normalized water-leaving radiance (nLw(λ)) values in the satellite observations of the Second-generation Global Imager (SGLI) sensor aboard the Global Change Observation Mission–Climate (GCOM-C) satellite. SGLI Level-2 data, along with atmospheric and in-water optical properties measured by the sun photometers in the AErosol RObotic NETwork-Ocean Color (AERONET-OC) from 26 sites globally, are utilized in this study. The focus is particularly on Tokyo Bay and the Ariake Sea, semi-enclosed water regions in Japan where previous research has pointed out the occurrence of negative nLw(λ) values due to atmospheric correction with SGLI. The study examines the temporal changes in atmospheric and in-water optical properties in these two regions, and identifies the characteristics of regions prone to negative nLw(λ) values due to atmospheric correction by comparing the optical properties of these regions with those of 24 other AERONET-OC sites. The time series results of nLw(λ) and the single-scattering albedo (ω(λ)) obtained by the sun photometers at the two sites in Tokyo Bay and Ariake Sea, along with SGLI nLw(λ), indicate the occurrence of negative values in SGLI nLw(λ) in blue band regions, which are mainly attributed to the inflow of absorptive aerosols. However, these negative values are not entirely explained by ω(λ) at 443 nm alone. Additionally, a comparison of in situ nLw(λ) measurements in Tokyo Bay and the Ariake Sea with nLw(λ) values obtained from 24 other AERONET-OC sites, as well as the inherent optical properties (IOPs) estimated through the Quasi-Analytical Algorithm version 5 (QAA_v5), identified five sites—Gulf of Riga, Long Island Sound, Lake Vanern, the Tokyo Bay, and Ariake Sea—as regions where negative nLw(λ) values are more likely to occur. These regions also tend to have lower nLw(λ) values at shorter wavelengths. Furthermore, relatively high light absorption by phytoplankton and colored dissolved organic matter, plus non-algal particles, was confirmed in these regions. This occurs because atmospheric correction processing excessively subtracts aerosol light scattering due to the influence of aerosol absorption, increasing the probability of the occurrence of negative nLw(λ) values. Based on the analysis of atmospheric and in-water optical measurements derived from AERONET-OC in this study, it was found that negative nLw(λ) values due to atmospheric correction are more likely to occur in water regions characterized by both the presence of absorptive aerosols in the atmosphere and high light absorption by in-water substances.

Cesium-based inorganic CsPbBr3 perovskite material possesses remarkable optoelectronic properties, such as high light absorption coefficient, high carrier mobility, and long diffusion length, and hence has promising applications in solar cells, photo-detectors, and high-energy radiation detectors, among others. Because of its simplicity, low cost, and high efficiency, spin-coating deposition for the CsPbBr3 perovskite layer for such diverse applications has been widely used. However, the spin-coating technique has technological constraints when it comes to uniformly deposit large-area films. Thermal evaporation, on the other hand, is inexpensive and produces a uniform and repeatable thin film. In this study, the stability, energy band alignment, surface morphologies, and light absorption of a CsPbBr3 perovskite layer produced by spin coating and thermal evaporation are investigated and discussed.

Due to its high light absorption coefficient and appropriate bandgap, CuInS2 (CIS) has been receiving much attention as an absorber material for thin film solar cells and also as a visible light photocatalyst. Herein we present heterostructured CIS/ZnO nanorods (NRs) in an attempt to enhance light absorption and facilitate charge separation/transfer in the photocatalysis system. CIS nanoparticles (NPs) were directly deposited on ZnO nanorod arrays (NRAs) to fabricate heterostructured CIS/ZnO NRAs using an environmentally benign, non-hydrazine solution reaction. These heterostructured NRAs are immobilized on FTO glass, which has additional merits of recyclability and bias-applicability. The ideal type-II band structure of CIS/ZnO enables efficient charge separation/transfer, which is confirmed by PL (photoluminescence) decay measurements. Also, the 1D-ZnO NR structure facilitates fast charge transfer along with enhancing light absorption via light scattering. These synergistic effects improved the photocatalytic activity in both organic dye and bacteria decomposition. The photodecomposition efficiency was further enhanced with an aid of external bias. The underlying photocatalytic mechanism was also investigated through controlled experiments under various scavenging conditions. The results suggest that reactive oxygen species (ROS) formed by multistep reduction of O2 play a main role in photocatalysis, while hole-induced photodecomposition is relatively deactivated due to the band structure of the heterostructures of CIS/ZnO.