Transmittance Research Articles

Abstract Electrochromic smart windows (ESWs), capable of dynamically modulating light transmittance, offer transformative potential for reducing building energy consumption. However, persistent challenges in manufacturing scalability and prohibitive production costs have hindered their commercial viability and widespread adoption. In this study, three distinct fabrication strategies, black phosphorus (BP)-assisted, MXene-assisted, and blank control growth, were systematically explored to synthesize WO3 films using a two-dimensional material assisted in-situ growth (TAIG) method. Comprehensive structural analysis revealed significant variations in film characteristics across the different material-assisted approaches, primarily manifested in oxygen vacancy concentration, structural water content and morphological uniformity. These differences directly correlated with divergences in electrochemical behavior, electrochromic performance, and long-term cycling stability. Notably, BP-assisted WO3 films demonstrated exceptional performance metrics, including outstanding optical modulation (82.94% at 1100 nm), ultrafast switching kinetics (coloration/bleaching times of 3.5/4.1 s), and record-high coloration efficiency (361.15 cm2C-1). Furthermore, the corresponding electrochromic devices retained 95% of their initial optical modulation after 10,000 operational cycles. This work advances fundamental understanding of TAIG mechanisms while providing actionable insights for scalable fabrication of high-performance ESWs.

Strawberry (Fragaria × ananassa Duch.) is an important crop in the world. Environmental fluctuations have a significant impact on the growth of strawberries. Photoconversion films can change the environment of facility crops to increase production and improve quality. Therefore, this study investigated the effects of rare earth light conversion films (RPOs) on strawberry cultivation. The temperature, photosynthetic photon flux density, light transmittance and proportion of spectra beneficial to the crop production of RPO greenhouses were all greater than those of the control. Compared with those of the control, spongy tissues were sparser in RPO1 and RPO2 leaves. The cross-sectional surface area of the main vascular bundles of strawberry petioles treated with RPO1 and RPO2 increased slightly. Compared with those of the control, net CO2 assimilation, stomatal conductance, activity of Rubisco and gene expression levels of RPO1 and RPO2 were all increased, and the intercellular CO2 concentration was decreased. Compared with those of the control, yield, soluble solids, soluble sugar content, Vc content, and flavonoid contents of RPO1 and RPO2 increased, while the soluble protein content decreased. In conclusion, RPO promotes photosynthesis in strawberry plants by optimizing photosynthetic photon flux density, spectrum and temperature in greenhouses; adjusting the spectrum to change pigment content, spongy tissue structure, petiole vascular bundles, and Rubisco activity; and regulating the expression of the Rubisco gene, thereby increasing the quality and yield of strawberry plants. Compared with RPO1, RPO2 could be a more suitable film for strawberry production.

Abstract Energy scarcity and electromagnetic microwave (EMW) management pose global challenges, yet integrating functionalities in a single material to manage ultrawide‐spectrum radiative energy from visible to microwave remains formidable. Here, sustainable yet appropriate cellulose and cellulose nanofibers (CNFs) are utilized to integrate silver nanowires and transition metal carbides, consequently yielding the large‐area, ultrathin, high‐strength, ultra‐flexible, and durable paper‐based window films toward advanced ultrawide‐spectrum heating and EMW attenuation. The ultrawide‐spectrum‐selective films demonstrate high visible light transmittance, near‐infrared photothermal conversion, mid‐infrared low emissivity‐induced passive radiative heating, and effective EMW attenuation, simultaneously elevating energy conversion efficiency and EMW management. Under a solar power density of 50 mW cm − 2 , a CAMC‐equipped room with dimensions of 30 × 20 × 18 cm 3 exhibits a temperature increase of 9.4 °C, outperforming other heating materials of identical dimensions and initial temperatures. Furthermore, they offer an adjustable range of optical transmittance and EMW shielding effectiveness (SE), with a thickness‐normalized specific SE ranging from 937 to 2562 dB mm −1 and transmittance between 80.3% and 55.1%, surpassing the reported materials.

Abstract Passive radiative cooling (PRC) smart windows possess great potential in thermal management and reducing building energy consumption. Polymer‐dispersed liquid crystal (PDLC) films capable of modulating solar light transmittance are attractive in fabricating dynamic PRC smart windows. Considering the striking photothermal effect of near‐infrared (NIR) light, effectively NIR light shielding is of significance to improve the PRC performance. Herein, a general strategy to enhance thermal management performance of PRC PDLC film is achieved by synergistic modulation of mid‐infrared (MIR), NIR, and visible wavelength ranges. The SiO 2 doped fluorinated PDLC (FPDLC‐SiO 2 ) film exhibits MIR emissivity of 94.2% and achieves a temperature reduction of 8.7 °C compared to the FPDLC film. After further integration of poly‐(vinylpyrrolidone) (PVP) functionalized cesium tungsten bronze (Cs 0.33 WO 3 ) (CWO) nanoparticles, the nanoparticle‐doped (FPDLC‐SiO 2 ‐CWO) film demonstrates considerable NIR shielding ability (Δ T NIR = 21.9%), solar modulation efficiency (Δ T sol = 22.8%) and high MIR emissivity (over 94%) within the atmospheric window. Outdoor temperature decreases by 4.3 °C compared to the FPDLC‐SiO 2 film. Thanks to the multiple modulating functionalities, the FPDLC‐SiO 2 ‐CWO film achieves comprehensive thermal management capabilities and an HVAC energy saving efficiency of 35.52% compared to Low‐E glass, demonstrating a competent candidate in fabrication of energy‐saving smart windows.

Cellulose nanocrystal composite films with bioinspired structural color for mechanically robust passive daytime radiative cooling.

This study investigated the effect of lead tetroxide nanoparticles (Pb3O4 NPs) on the properties of polyvinyl alcohol (PVA). PVA films were prepared by a conventional casting method, with varying concentrations of Pb3O4 NPs (0, 2, 4, 6, 7, and 9 wt %). A significant increase in the crystallinity of the PVA film with increasing Pb3O4 NPs concentrations and the uniform distribution of Pb3O4 NPs on the surface of the films were demonstrated using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM), respectively. Optical characterizations revealed increased light absorption and decreased light transmittance with increasing Pb3O4 concentration. Among the significant optical results, the band gap energy of the samples decreased from 4.95 to 3.77 eV for pure PVA and PVA/9% Pb3O4. The radiation blocking capabilities of the PVA films were investigated experimentally using a NaI (Tl) detector and theoretically using Phy-X/PSD software in the gamma-ray energy range (0.511–1.332) MeV. The experimental and theoretical results were consistent, highlighting that higher concentrations of Pb3O4 improve the effectiveness of PVA films in reducing gamma ray penetration. Thus, the control of the filler concentrations to enhance the shielding properties will open up a new strategy to synthesize novel materials for radiation applications.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-22740-6.

For effective solar radiation management, windows in sustainable buildings need to feature high visible light transmittance to support daylighting needs, block unwanted solar radiation, and maintain an appropriate photothermal performance. However, materials with a high photothermal performance usually do not exhibit favorable light transmittance. Here, the selectively transparent photothermal tannic acid-grafted Cu1.95S and MoS2 heterojunction (Cu1.95S/TA-MoS2) was prepared with a mild one-pot synthesis. On the one hand, TA not only grafts both MoS2 and Cu1.95S but also effectively absorbs ultraviolet light. On the other hand, the incorporation of Cu1.95S enhances near-infrared absorption. The selectively transparent photothermal membrane was fabricated by blending Cu1.95S/TA-MoS2 with poly(vinyl alcohol). Compared with the TA-MoS2 membrane, the Cu1.95S/TA-MoS2 membrane achieved a 25.3% reduction in solar transmittance with only a 6.3% loss in luminous transmittance. Moreover, via Cu1.95S with localized surface plasmon resonance properties and a synergistic effect with MoS2, the photothermal equilibrium temperature of the Cu1.95S/TA-MoS2 membrane was increased by 23.4 °C. The membrane demonstrates effective antifogging capability and generates a stable voltage of 0.14 V when integrated with thermoelectric modules. This work provides solid support for next-generation solar radiation management in building windows.

Real-time monitoring of dose delivery is critical for ensuring reliable and energy-efficient ultraviolet (UV) disinfection. However, conventional methods are limited by high cost and inability to capture full dose distribution information. This study presents a novel, cost-effective approach for real-time monitoring of UV dose delivery (including dose distribution and simplified indicators) by integrating a dual microfluorescent silica detector (dual-MFSD) system with Buckingham-π theorem-based scaling. The dual-MFSD system enabled simultaneous and convenient monitoring of real-time water UV transmittance (TRT), as well as a correction factor (CFRT) accounting for lamp output attenuation and sleeve fouling, with an effective optical path-length difference calibrated as 1.01 cm. A dimensionless scaling method based on the Buckingham-π theorem was developed to predict full information of the UV dose distribution using real-time operating parameters (i.e., TRT, flow rate (QRT), and CFRT), allowing rapid calculation of simplified indicators. The predicted doses were validated by computational fluid dynamic (CFD) simulation and biodosimetry at various TRT values (97% and 90%) and QRT values (40, 50, and 60 L min-1) with a measured CFRT (0.754). Additionally, a four-month field test was conducted in a secondary water supply system, demonstrating the practical applicability of this method. This study provides a real-time approach for UV dose monitoring, supporting reliable and energy-efficient UV disinfection.

Black polyimide (BPI) has shown important value in the field of optical engineering due to its excellent light shielding, high temperature stability, and mechanical strength. However, carbon materials or organic dye-doped BPI suffer from poor insulation, low mechanical strength, and poor thermal stability. Intrinsic BPI has gradually become a hot topic of research at this stage. Polyimides containing dianiline structure have unique reducing activity, and the visible light absorption range can be expanded by adding an oxidant in situ to achieve BPI preparation. In this work, a polymerizable dianiline derivative- 2,4-diaminodiphenylamine (NPDA) has been developed. The resulting diamine monomers were then polymerized with a dianhydride monomer via a conventional two-step method to prepare soluble polyimide. The diphenylamine-containing group PI was characterized by 1H NMR, FTIR and UV absorption spectroscopy. It was found that by changing the oxidant ratio, a yellow, red and even black controllable polyimide film could be obtained. When fully oxidized, the BPI cutoff wavelength red shifts to 591 nm, light transmittance reaches as low as 5.9% (full visible light 300–700 nm mean), and BPI can maintain the electrical insulation and heat resistance of polyimide. This method of oxidizing soluble polyimide in situ has advantages such as economy, universality, process consistency, ease of access and superior performance.

Cellulose nanofiber (CNF) aerogels can offer both transparency and thermal insulation but typically suffer from mechanical weakness. Here, we report a wet-state densification strategy to overcome this limitation. Flowable CNF dispersions were converted to self-supporting hydrogels via inter-CNF cross-linking with zirconium ions (Zr4+), followed by uniaxial compression and supercritical drying to produce aerogels with bulk densities of 25-95 mg cm-3. The compression induced a uniform anisotropic layered structure while maintaining mesopores of 10-60 nm and specific surface areas of 380-440 m2 g-1. The aerogels with the highest density of 95 mg cm-3 attained an outstanding tensile stiffness (Et ∼ 122 MPa), while their light transmittances and thermal conductivity remained approximately 75% at 600 nm and 21 mW m-1 K-1, respectively, even after densification. This wet-state densification of CNF hydrogels delivers specific aerogels that combine the excellent features of mechanical robustness, optical transparency, and thermal superinsulation.

In order to prevent the occurrence of wall sticking during the polymerization process of ether-linked PA6T, meta-ether bonds were introduced into the molecular chain of ether-linked PA6T to improve its dissolving property and endow it good optical property. Briefly, the semi-aromatic copoly(ether ether amide)s (P1–P6) with ortho and meta ether bonds were synthesized by the nucleophilic substitution reaction using 1, 6-N, N’-bis(4-fuorobenzamide) hexane, 1, 4-benzenediol and resorcinol as the raw materials in this work. As the molar ratio of resorcinol reached up to 10%, no obvious wall-clogging phenomenon occurred during the reaction, and the reaction solution was a uniform and viscous liquid. The inherent viscosities of the synthesized copolymers P1–P6 were 0.425–0.748 dLg−1. The glass transition temperatures (Tg) of them were 121.1–137.9 °C, the weight-loss temperatures (T5%) were 390.2–441.1 °C, and the heat resistance indexes (HRI) were 209.2–225.0 °C. The tensile strengths of the copolymers were 62.1–70.1 MPa. The solubility of the copolymers P5, P6 bad better dissolving property than that of P1–P4, they can be dissolved in NMP at room temperature. The copolymers P4–P6 had good light transmittance while the other copolymers not due to their non-crystalline natures, the optical transmittance of them were 76.2%–85.9% at 450 nm.

Low-emissivity (low-e) coatings are used in architectural and automotive glazing for energy-saving applications. These are used to minimise heat transmission through the windows by reflection. Low-e coatings are semi-transparent coatings that typically comprise a metallic layer that reflects infrared light, sandwiched between two dielectric layers that protect the metal and enhance its visible transmittance. Ag is usually used as the metallic layer because of its colour neutrality and low optical absorption in the visible range. However, Ag-based low-e coatings easily degrade upon atmosphere exposure; therefore, they need to be placed inside the cavities of multiple-pane windows. In this paper, Au was used as an alternative to Ag and was sandwiched between WO3, SnO2 and Nb2O5 dielectric layers. The thickness of each layer was optimised to achieve the highest visible transmittance and infrared reflectance. The durability of the coatings was assessed by means of corrosion and abrasion resistance tests. We demonstrate that the Nb2O5/Au/Nb2O5 coating system provides a visible light transmittance of 56%, an emissivity as low as 0.04 and outstanding corrosion resistance (1000 h of salt spray testing), indicating its excellent potential to be used as first surface low-e coating.

Benzoheterocycle polyimides (PIs) demonstrate exceptional metal substrate adhesion, positioning them as high-performance alternatives to conventional heterogeneous adhesives. These materials significantly enhance the weather resistance of flexible batteries and facilitate the development of thinner and lighter PI-based aluminum-plastic flexible packaging. Through molecular engineering of benzoheterocycle PI backbones, a series of ternary copolyimides (BIBOPIs) were synthesized utilizing four structurally distinct flexible diamine monomers. The thermodynamic properties, solvent resistance, water absorption, and coating adhesion of BIBOPIs were systematically evaluated. The distinctive molecular architectures of flexible diamines impart unique physicochemical properties to BIBOPIs. The light transmittance of BIBOPIs incorporating 4,4′-diaminodiphenylsulfone (DDS) exceeds 73%, with BIBOPI-0.5DDS achieving a transmittance of 85% at a wavelength of 800 nm. The light transmittance of BIBOPI-0.5RODA is reduced compared to that of BIBOPI-0.3RODA as the content of flexible ether groups in the molecular chain increases, consequently limiting its visible light transmittance. With the incorporation of a third monomer, the glass transition temperature (Tg) values of BIBOPIs demonstrate a consistent decrease, ranging from 332 to 410 °C. With the increase in 1,4-bis(4-aminophenoxy)benzene (RODA) ratio, the elongation at break of BIBOPIs exhibits a significant rise, from 6.8% for BIBOPI-0.1RODA to 33.8% for BIBOPI-0.5RODA. BIBOPIs demonstrate exceptional solvent resistance at both ambient and elevated temperatures. Additionally, the water absorption (WA) of BIBOPIs decreases as the proportion of the third component increases. The adhesion grade of BIBOPI coatings is 0, with the exception of BIBOPI-0.1DDS, BIBOPI-0.1BPDA, and BIBOPI-0.1ODA. Pull-off experiments demonstrate that the incorporation of a flexible third monomer enhances the adhesion between BIBOPI coatings and substrates, with the adhesion strength surpassing 21.7 MPa. Unlike previous studies, the PI coating developed in this research enables the formation of a metal substrate protective layer with excellent adhesion, achieved through molecular design and structural optimization, without requiring complex surface treatment techniques. The optimized coating architecture enables molecular-level integration with dense PI protective layers, providing critical insights for developing advanced benzoheterocycle PI-based aluminum-plastic flexible packaging systems.

Ultraviolet radiation (UVR) is a well-established risk factor for ocular diseases; however, the ultraviolet-blocking properties of daily disposable contact lenses remain insufficiently characterized. This study evaluated thirteen commercially available lenses to determine their spectral transmittance across UV-B, UV-A, and visible light ranges using a UV–visible spectrophotometer. The oxygen permeability, central thickness, water content, and FDA material classification of each lens were documented, and oxygen transmissibility was subsequently calculated. A generalized linear mixed model (GLMM) was applied to identify predictors of spectral transmittance. All lenses demonstrated high visible light transmittance (>88%), but exhibited substantial variation in UV attenuation. While several lenses effectively blocked most UV radiation, others transmitted more than 70%. The analysis revealed that lens power was the most consistent predictor of spectral transmittance, with higher minus powers associated with reduced UV-blocking efficacy. Moisture content and material classification also influenced UV protection but had minimal effect on visible light transmission. In conclusion, daily disposable contact lenses vary considerably in their UV-blocking capabilities, and although lens power cannot be altered, consideration of material composition and UV transmittance properties may assist in selecting lenses that provide optimal ocular protection.

The food packaging industry is inclined toward biodegradable films, and jellyfish hold significant potential for exploitation due to their extraordinary collagen content. Thus, the primary objective of this research was to develop an antioxidant gelatine-based film from the blue cannonball jellyfish (Stomolophus sp. 2) (JG), using chitosan (CH) and the casting method, with glycerol (GLY) as a plasticiser to improve film flexibility. The JG obtained through alkaline, heat, and dialysis treatment exhibited high in vitro antioxidant activity. A commercial chitosan acetic acid solution (1%) was added to a JG water solution (1%) and a commercial gelatine (CG) solution (1%) was employed as a control. The film’s mass ratio was 4:1:2 (JG:CH:GLY). The physical, chemical, thermal, mechanical, and antioxidant properties of the JG-CH and CG-CH films were compared; JG-CH showed higher solubility and thermal stability than CG-CH. The colour and light transmittance were similar; however, their tensile strength and elongation differed. Furthermore, JG-CH films exhibited a higher ABTS radical-scavenging capacity compared to CG-CH films. FTIR and 1H NMR spectra of the JG-CH films indicated excellent compatibility between the components, primarily due to hydrogen bonding. This study demonstrates that JG-CH films possess functional properties that make this material suitable for application as a biomaterial film for food.

Sea ice modulates the transfer of shortwave radiative energy fluxes within the Arctic atmosphere-sea-ice-ocean system. Understanding and predicting these fluxes comes with greatest uncertainties during the melt and freeze-up seasons, when the sea ice surface is strongly heterogeneous and changing rapidly. Then, the partitioning of solar radiative fluxes between atmosphere, ice, and ocean has greatest impacts on the surface energy budget, controlling sea ice melt and formation. Here, we investigated changes and impacts of sea ice surface variability by analyzing high-resolution red-green-blue aerial imagery obtained during the Multidisciplinary Observatory for the Study of Arctic Climate (MOSAiC) expedition in 2020. We used pixel brightness from processed aerial images as a proxy of surface albedo, because such data are frequently available and obtainable from commercial digital cameras. The results allowed quantification of fluxes on floe-scales and also revealed the seasonality of sea ice spatial heterogeneity, which was strongest in the middle of melt season driven by melt pond processes. On scales of 10 m × 10 m, a magnitude larger than the traditional single in-situ optical observations (although many are made over larger scales), distinct surface conditions, for example, individual melt ponds, resulted in differences of energy deposition into the ice by more than 600%. The effects of spatial variability were minimized by integrating over areas 200 m × 200 m and larger. We suggest considering these scales for future energy budget studies and airborne observations, because sufficient parts of different surface features are included. The concept of surface brightness and aerial photographs might help to bridge in-situ observations to even larger scales, including fractions of open water. It may also be used to upscale observations of under-ice light regimes by providing spatially continuous surface brightness that governs the light transmittance, thus to improve our understanding of the coupled system, including ecological functions.

Building energy conservation through the development of transparent thermal insulation materials that selectively block near-infrared radiation while maintaining visible light transmittance has emerged as a key strategy for global carbon neutrality. WO3 is a semiconductor oxide with near-infrared absorption capabilities. However, the limited absorption efficiency and narrow spectral coverage of pure WO3 significantly diminish its overall transparent thermal insulation performance, thereby restricting its practical application in energy-saving glass. Therefore, this study successfully prepared Sn-doped WO3 materials using a one-step hydrothermal method, controlling the Sn:W molar ratio from 0.1:1 to 2.0:1. Through evaluation of transparent thermal insulation performance of a series of Sn-doped WO3 samples, we found that Sn:W = 0.9:1 exhibited the most excellent performance, with NIR shielding efficiency reaching 93.9%, which was 1.84 times higher than pure WO3. Moreover, this sample demonstrated a transparent thermal insulation index (THI) of 4.38, representing increases of 184% and 317%, respectively, compared to pure WO3. These enhancements highlight the strong NIR absorption capability achieved by Sn-doped WO3 through structural regulation. When Sn doping reaches a certain concentration, it triggers a structural transformation of WO3 from monoclinic to tetragonal phase. After reaching the critical solubility threshold, phase separation occurs, forming a multiphase structure composed of a Sn-doped WO3 matrix and secondary SnO2 and WSn0.33O3 phases, which synergistically enhance oxygen vacancy formation and W6+ to W5+ reduction, achieving excellent NIR absorption through small polaron hopping and localized surface plasmon resonance effects. This study provides important insights for developing high-performance transparent thermal insulation materials for energy-efficient buildings.

Smart windows (SWs) with energy-saving capabilities can dynamically regulate light transmittance and window optical characteristics, which is crucial for building energy efficiency. As a kind of typical wet-soft material, hydrogels have programmable network structures, excellent mechanical flexibilities, and multifunctionality, thus enabling them to be one of the most promising candidates to construct multifunctional SWs. However, although the rapid advance of SWs technology, various types of SWs, including thermo-, electro-, photochromic SWs, have been extensively reported, the recent research development, current challenges, and future perspectives of hydrogel-based smart windows (HSWs) have been rarely demonstrated. This review systematically summarizes the research progress of HSWs, comprising thermochromic, electrochromic, photochromic, humidity-responsive, mechanochromic, magnetochromic, and salt-responsive HSWs in recent years. First, the fabrication strategies for every HSW are presented, particularly focusing on functional materials, working principles, and property enhancement. Meanwhile, the strengths and weaknesses of every HSW are summarized and compared. Then, some emerging technologies, such as double-stimulus-triggered HSWs and multifunction-integrated devices, are discussed. Finally, the existing issues and future opportunities for HSWs are demonstrated to facilitate future scientific research and practical applications.

The Role of Blue Light-Filtering and Premium Intraocular Lenses on Postoperative Falls: A Nationwide Target Trial Emulation in Taiwan.

The prolonged retention of senescent branches and needles (canopy litter) in Cunninghamia lanceolata canopies is an evolutionary adaptation, yet its impacts on stand microenvironment and understory succession remain poorly quantified. To address this gap, we conducted a 5-year field experiment across six planting densities (1800, 2400, 3000, 3600, 4200, and 4800 trees·ha−1), aiming to evaluate the effects of canopy litter removal on canopy structure, forest light environment, and understory biodiversity. Results demonstrated that leaf area index (LAI) and mean tilt angle of the leaf (MTA) significantly increased with density (p < 0.05), leading to marked reductions in photosynthetic photon flux density (PPFD) and light transmittance (T). Canopy litter removal significantly reduced LAI across all densities after 4–5 years (p < 0.05) and consistently enhanced PPFD and transmittance (p < 0.01). MTA and light quality parameters (red:blue and red:far-red ratios) both exhibited variable responses to litter removal, driven by density and time interactions, with effects diminishing over time. Understory vegetation diversity exhibited pronounced temporal dynamics and density-dependent responses to canopy litter removal, with increases in species richness (S), Simpson diversity (D), and Shannon–Wiener diversity (H), while Pielou Evenness (J) responded more variably. The most notable increase in species richness occurred in the 4th year, when 21 new species were recorded, largely due to the expansion of light-demanding bamboos (e.g., Indocalamus tessellatus and Pleioblastus amarus), heliophilic grasses (e.g., Lophatherum gracile) and pioneer ferns (e.g., Pteris dispar and Microlepia hancei). Correlation analyses confirmed PPFD as a key positive driver of all diversity indices (p < 0.01), whereas LAI was significantly negatively correlated with PPFD, light transmittance, and understory diversity (p < 0.01). These findings demonstrate that strategic management of canopy litter incorporating stand density regulation can improve understory light availability, thereby facilitating heliophilic species recruitment and biodiversity enhancement in subtropical coniferous plantations.