Solar Modulation Research Articles

The synergistic effect of Ta-doping and antireflective TaOx layer on the thermochromic VO2 thin films for smart windows

Current efforts to promote the use of VO2 materials as a promising candidate for thermochromic smart windows continue to be hindered by the low luminous transmittance (Tlum), the limited solar modulation ability (ΔTsol), the high phase transition temperature (Tt, ∼68 °C) and the wide thermal hysteresis (ΔT). The present work addresses these issues by fabricating an antireflective TaOx layer on the Ta-doped VO2 (i.e., VO2(Ta)) thin films. The VO2(4.35 at% Ta) thin films with low Tt of 29.87 °C and narrowed ΔT of almost zero were grown on glass substrates by magnetron sputtering at room temperature followed by rapid thermal annealing. However, the VO2(Ta) thin films show slightly enhanced Tlum of 38.31 % compared with undoped VO2 films (35.46 %) and decreased the ΔTsol by 1.83 %. The thermochromic properties are further enhanced by depositing the antireflective TaOx layer onto the VO2(Ta) thin film by reactive magnetron sputtering, which significantly increases the Tlum from 38.31 % to 48.58 %, marginally decreases the ΔTsol from 4.44 % to 4.12 %, and maintain the Tt and ΔT constant. These results verify the possibility of developing VO2 films with simultaneously increased optical transmittance, decreased Tt to suitable values, and extremely narrow ΔT by using the synergistic effect of element doping and constructing an antireflective layer.

VO2-based colorful smart windows with self-cleaning function

Smart windows hold promise for mitigating energy demand for indoor heating or cooling. However, VO2-based thermochromic smart windows face challenges such as high phase transition temperature, limited window color options, and a lack of functional diversity. Herein, we investigated the colorful smart windows utilizing the tungsten-doped VO2 thin films with the phase transition temperature of approximately 23.5 °C. The surface color of these smart windows can be dynamically adjusted from brown to purple, cyan, yellow, and red by tuning the thickness of the wave-impedance matching layer of HfO2 film, resulted from the interference effect of the HfO2 layer and the underlying WxV1-xO2 layer. Moreover, the HfO2-coated WxV1-xO2 thin film with the HfO2 thickness of 132 nm demonstrates superior optical performance with a solar modulation ability of 9.35 %, the low-temperature luminous transmission of 36.81 %, and the high-temperature luminous transmission of 38.03 %. In addition, the incorporation of SiO2 nanoparticles into the HfO2-coated WxV1-xO2 thin films results in the superhydrophobic property with a water contact angle of 162.1° due to the formed rough surface, which is favor to the self-cleaning of the windows surface.

Search for Periodic Time Variations of the Solar B8 Neutrino Flux between 1996 and 2018 in Super-Kamiokande

We report a search for time variations of the solar B8 neutrino flux using 5804 live days of Super-Kamiokande data collected between May 31, 1996, and May 30, 2018. Super-Kamiokande measured the precise time of each solar neutrino interaction over 22 calendar years to search for solar neutrino flux modulations with unprecedented precision. Periodic modulations are searched for in a dataset comprising five-day interval solar neutrino flux measurements with a maximum likelihood method. We also applied the Lomb-Scargle method to this dataset to compare it with previous reports. The only significant modulation found is due to the elliptic orbit of the Earth around the Sun. The observed modulation is consistent with astronomical data: we measured an eccentricity of (1.53±0.35)%, and a perihelion shift of (−1.5±13.5) days. Published by the American Physical Society 2024

Variations in the Solar Modulation Parameter Over the Last 9.5 Thousand Years and the Tilt of the Geomagnetic Dipole

Background: Calculations of the solar modulation parameter (Φ) over the past millennia typically use the relationship between the production rate of cosmogenic isotopes, the earth's dipole moment, and the magnitude of Φ. The cosmogenic isotopes 14C and 10Be are typically used in these studies. When studying solar modulation, the cyclic change in dipole tilt is usually not taken into account, which affects estimates of past solar activity. Methods: Tree rings are a reliable basis for obtaining a radiocarbon time scale (IntCal13). However, determining the concentration of 14C in tree rings is a difficult and controversial task. The time scale derived from the 10Be production rate simulation (GICC05) is less reliable. Nevertheless, there is a way to combine the accuracy of the radiocarbon time scale with the reliability of estimates of the 10Be production rate. This method is the synchronization of the radiocarbon and beryllium-10 series. We have selected the most relevant methods for calculating the solar modulation parameter Φ for the Holocene. When calculating Φ, 10Be data synchronized with 14C data were used. The latest data on the earth's dipole moment were considered. Empirical Mode Decomposition (EMD) was used in the analysis of Φ. Results: It has been shown that the first two decomposition modes are oscillating components with periods of 710 and 208 years, the amplitudes of which increase with time, reaching a maximum of 2500 BP. From contemplation, it follows that the 710-year oscillations are apparently caused by fluctuations in the tilt of the earth's dipole. After excluding the EMD component associated with the 710-year cyclicity, a corrected series was obtained for the solar modulation parameter, free from the influence of changes in the tilt of the magnetic dipole. Conclusion: The rate of formation of cosmogenic radionuclides depends on the intensity of penetration of Galactic Cosmic Rays (GCRs) into the earth's atmosphere. Before reaching earth, GCRs must cross the heliosphere, where they are exposed to solar modulation. Adequate consideration of solar modulation parameters is important for the correct interpretation of the rate of production of cosmogenic isotopes and solar activity.

Chemical and physical effects of the addition of thermochromic VO2 particles to cement

This work aims to deepen the knowledge of systems formed by cement and thermochromic vanadium dioxide particles. Cement paste specimens with 9 % addition of monoclinic VO2 particles show a significant delay of the hydration at early ages with respect to plain cement specimens, seemingly due to the partial inhibition of hydrates precipitation during the first 24 h of reaction. Upon further hydration, a re-activation of the hydration reactions gives rise to a higher mechanical strength and a more refined pore structure in the paste with VO2 addition at 28 days, attributed to the enhanced formation of C–S–H. The stability of the VO2 particles within the matrix is confirmed along the hydration process and provides the cement paste with the associated thermochromic behavior that is demonstrated by a change in the reflection in the near infrared wavelength range upon cooling from 70 °C. The results confirm the viability of producing VO2-based thermochromic cementitious materials for building envelopes. The next steps in their development should target the enhancement of the solar reflectance modulation in order to produce a significant impact in the energy efficiency of buildings and the urban overheating effect.

Constraining primordial black holes as dark matter using AMS-02 data

Primordial black holes (PBHs) are the plausible candidates for the cosmological dark matter. Theoretically, PBHs with masses MPBH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M_{\ extrm{PBH}}$$\\end{document} in the range of 4×1014∼1017g\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$4\ imes 10^{14}\\sim 10^{17}\\,\ extrm{g}$$\\end{document} can emit sub-GeV electrons and positrons through Hawking radiation. Some of these particles could undergo diffusive reacceleration during propagation in the Milky Way, potentially reaching energies up to the GeV level observed by AMS-02. In this work, we utilize AMS-02 data to constrain the PBH abundance fPBH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f_{\ extrm{PBH}}$$\\end{document} by employing the reacceleration mechanism. Under the assumption of a monochromatic PBH mass distribution, our findings reveal that the limit is stricter than that derived from Voyager 1 data. This difference is particularly pronounced when MPBH≲1015g\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M_{\ extrm{PBH}}\\lesssim 10^{15}\\,\ extrm{g}$$\\end{document}, exceeding an order of magnitude. The constraints are even more robust in a more realistic scenario involving a log-normal mass distribution of PBHs. Moreover, we explore the impact of varying propagation parameters and solar modulation potential within reasonable ranges, and find that such variations have minimal effects on the final results.

SPCM@PNIPAm-PAM hydrogel thermochromic smart windows with multi-stage optical modulation for building energy saving

As a bridge connecting indoor and outdoor environment, windows cause extremely high energy consumption, and near infrared light entering rooms is the primary reason for the increase of cooling load in summer. Thermochromic smart windows, which dynamically regulate light transmittance through stimulus–response mechanism, aroused enormous interest in building energy-saving. However, the development of traditional thermochromic smart windows is often limited by single function and inappropriate response temperature. Herein, a novel fully autonomous multi-stage thermal-response@storage (MTRS) smart window that responds to the ambient temperature was designed by using the thermoresponsive SPCM@PNIPAm-PAM hydrogel for energy-saving and privacy protection. The SPCM@PNIPAm-PAM hydrogel exhibited satisfactory luminous transmittance of 62.70 % and solar modulation ability (ΔTsol,25-40°C=27.39 %, ΔTsol,40-55°C= 19.28 %). With the temperature changing from low (<28 °C) to medium (28–45 °C) to high (>45 °C), the MTRS smart window realized the multi-stage reversible transition from opaque to transparent to opaque, which achieved privacy protection at night and thermal insulation during the day. The obtained MTRS smart window achieved a peak temperature drop of 12.14 °C compared with the regular window on a certain day in the midsummer in Tianjin region. Based on this day’s temperature data, the cooling load of was calculated, and the energy saving was further calculated, which was as high as 21.37 %. The proposed work has a great significance for further development of effective smart windows and deserves attention for the future design of windows for energy saving.

Enhanced visible transmittance with low phase transition temperature of VO2 enabled by W-Mg co-doping

Vanadium dioxide (VO2) is a promising thermochromic material for smart windows. However, the relatively high phase transition temperature (Tt) and low visible transmittance (Tlum) constrain its practical application. Cationic co-doping offers an effective strategy to optimize the optical switching properties near room temperature. In this line, herein, the W-Mg co-doped VO2 films were synthesized by a solution and annealing method from W-Mg co-doped ammonium citrato-oxovanadate (IV). The synergistic effect of W-Mg co-doping improves the performance of VO2 films with Tt of 42.6 °C, Tlum of 59.0 % and solar energy modulation of 12.8 %. By changing the amounts of Mg, the W-Mg co-doped VO2 film maintains the low Tt of W-VO2 film and meanwhile possesses higher Tlum, which is attributed to the band gap structure change induced by the W-Mg co-doping. The excellent optical, thermochromic and thermal insulation performances confirm that our research could provide guidance for advancing the application of VO2 in smart window fields.

2D ordered porous VO2-based composite film with enhanced thermochromism performance and high stability for smart windows

Thermochromic vanadium dioxide (VO2) can autonomously adjust near-infrared light transmittance in response to the external temperature changes, offering a significant reduction in building energy consumption when applied it in smart window. However, it is a big challenge for simultaneous optimization of visible light transmittance, solar modulation ability, and stability in VO2. To address such a big challenge, this study successfully prepared a 2D ordered porous VO2@Zn3V3O8 composite film. The as-obtained film exhibits exceptional optical performance with a visible light transmittance (Tlum) of 62.75 % and the solar modulation ability (ΔTsol) of 10.62 %, based on the anti-reflective effects of porous structure and the localized surface plasma resonance (LSPR) absorption of independently distributed VO2 nanoparticles. In addition, the composite structural film showcases excellent environmental durability that 80 % of ΔTsol could be retained after 30 days aging under the conditions of 50 % humidity and 100 °C. This work propels the practical application of VO2 smart windows and offers valuable insights for the design of composite structures.

“Change According to the Situation” – Color‐Accommodative Nature‐Skin‐Derived Thermochromic Membrane for Active All‐Season Thermal Management

AbstractEnergy crisis and worsening greenhouse effects cause unprecedented global environmental and economic‐sustainability challenges. The emerging all‐season thermal regulation technology that can provide comfort to humans without consuming external‐energy demonstrates promising prospects. Inspired by the temperature‐accommodative skin of the color‐changing rain‐frog, a biodegradable nature‐skin‐derived thermochromic membrane (PCTM‐H) is nano‐engineered for active all‐season thermal management using the integrative interfacially wet‐casting film‐forming and spraying strategy of nature‐skin to incorporate polyvinyl alcohol and thermochromic microcapsules. Its outstanding thermochromic origins allow it to switch adaptively between cooling and heating modes without additional energy input. PCTM‐H has a light color with high reflectivity in hot summer and a dark‐color that absorbs solar radiation in cold winter, with an overall visible light modulation of ≈53.5%, solar modulation of ≈32.2%, and a remarkable emissivity in mid‐infrared band (≈86.7%). PCTM‐H has exceptional adaptive thermal management capabilities for multitudinous outdoor‐applications. Simulation results show that PCTM‐H has prominent energy‐saving efficiency in cities with different climate zones when utilized as roof‐protection membranes. Additionally, the distinguished mechanical features, weatherability, and bio‐degradability of PCTM‐H substantially increase its potential applications. This study provides a reference for the development of active all‐season thermal management materials and high‐value utilization of nature‐skin, contributing to the goal of carbon‐neutrality.

Constructing a New Biomass-Based Bistatic Window for Solar Regulation.

Smart windows effectively respond to the ever-changing climatic conditions, offering a smart solution for low-carbon buildings. However, current smart windows derived from chromic materials often have inferior solar modulation ability, or showcase high haze that obstructs outdoor views. Here, instead of developing new chromic materials, a new bistatic window is proposed for ultra-high solar modulation and luminous transmission. The new developed window can reduce the indoor surface temperature for ≈11°C, and reduce the building space cooling and heating energy consumption by 30% to 40%, providing significant energy-related advances over traditional smart windows. In detail, the bistatic window exhibits excellent solar modulation ability (ΔTsol = 61%), high visible transmittance in both bleached (Tlum,bleached = 91%) and colored (Tlum,colored = 56%) states, low haze (< 1%), rapid switching response (switching time < 1 min), high color rendering index (CRI > 80), and long-cyclic stability after 1000 cycles. With the advantages of facile fabrication and scalability, it is foreseen the developed bistatic window holds promising prospect for the next-generation low-carbon buildings, paving a new way for future advancements in the fields of smart windows.

A new analytical model of the cosmic-ray energy flux for Galactic diffuse radio emission

Low-frequency radio observations of diffuse synchrotron radiation offer a unique vantage point from which to investigate the intricate relationship between gas and magnetic fields in the formation of structures within the Galaxy, spanning from the diffuse interstellar medium (ISM) to star-forming regions. Achieving this pivotal objective hinges on a comprehensive understanding of cosmic-ray properties; these dictate the effective energy distribution of relativistic electrons, which are primarily responsible for the observable synchrotron radiation. Notably, cosmic-ray electrons (CRe) with energies of between 100 MeV and 10 GeV play a crucial role in determining the majority of the sky brightness below the GHz range. However, their energy flux (je) remains elusive because of solar modulation. We propose a way to derive observational constraints on this energy gap of interstellar CRe through the brightness temperature spectral index of low-frequency radio emission, here denoted βobs. We introduce a new parametric analytical model that fits available data for je in accordance with the βobs values measured in the literature between 50 MHz and 1 GHz for diffuse emission in the Milky Way. Our model accounts for multiple observations considering magnetic-field strengths consistent with existing measurements below 10 μG. We present a first all-sky map of the average component of the magnetic field perpendicular to the line of sight and validate our methodology against state-of-the art numerical simulations of the diffuse ISM. This research makes headway in modeling Galactic diffuse emission with a practical, parametric form. It provides essential insights that will help preparations for the imminent arrival of the Square Kilometre Array.

Analysis of the spectrum of 27-day GCR variations in 2015–2016

This work presents the results of the analysis of 27-day variations in the flux of galactic protons registered by STEREO, SOHO, and AMS-02 in 2015–2016. We calculate variations’ amplitude using several different approaches and propose a description of its energy dependence in the range of magnetic rigidity from approximately 0.3 to 100 GV. We also analyse variations of the solar modulation potential, which is the only parameter of force-field model, and consider the possibility of describing the 27-day variations of galactic cosmic rays within the framework of this model. It is shown that rigidity dependence of the 27-day variations amplitude cannot be properly described using this simple approximation.

Transport parameters from AMS-02 F/Si data and fluorine source abundance

The AMS-02 collaboration recently released cosmic ray F/Si data with an unprecedented accuracy. Cosmic ray fluorine is predominantly produced by fragmentation of heavier progenitors, while silicon is mostly accelerated at source. This ratio is thus maximally sensitive to cosmic ray propagation. We study the compatibility of the transport parameters derived from the F/Si ratio with those obtained from the lighter Li/C, Be/C, and B/C ratios. We also inspect the cosmic ray source abundance of F, which is one of the few elements that has a high first ionisation potential but is only moderately volatile and is a potentially key element to study the acceleration mechanism of cosmic rays. We used the 1D diffusion model implemented in the code and performed $ analyses accounting for several systematic effects (energy correlations in data, nuclear cross sections, and solar modulation uncertainties). We also took advantage of the nuclear database to update the F production cross sections for its most important progenitors (identified to be 56Fe, 32S, 28Si, 27Al, 24Mg, 22Ne, and 20Ne). The transport parameters obtained from AMS-02 F/Si data are compatible with those obtained from AMS-02 (Li,Be,B)/C data. The combined fit of all of these ratios leads to a $ 1.1$, with $ 10&lt;!PCT!&gt;$ adjustments of the B and F production cross sections (which are based on very few nuclear data points and would strongly benefit from new measurements). The F/Si ratio is compatible with a pure secondary origin of F, with a best-fit relative source abundance F/^ Si) CRS $ and an upper limit of $ $. Unfortunately, this limit is not sufficient to test global acceleration models of cosmic ray nuclei, for which values at the level of $ $ are required. Such levels could be attained with F/Si data with a few percent of accuracy at a few tens of TV, which is possibly within reach for the next generation of cosmic ray experiments.

Emerging Thermochromic Perovskite Materials: Insights into Fundamentals, Recent Advances and Applications

AbstractThermochromic perovskite materials exhibit reversible color changes in response to external thermal stimuli. Recently recognized as promising candidates, significant efforts are dedicated to developing these materials with tunable properties, rapid response, and effective light modulation. This review demonstrates recent advances in fabrication methods, mechanism investigation, solar modulation performance, and diverse applications of perovskite thermochromic materials. Thin films and single crystals are addressed separately, with a focus on achieving high‐quality and stable thermochromic perovskite materials across different dimensional architectures. Furthermore, the article outlines current challenges and provides forward‐looking perspectives, aiming to foster future innovative research and widespread application in smart windows, switchable photovoltaic devices, photo/thermal detectors, and anti‐counterfeiting technologies.

Temporal Variability of Equatorial Ionization Anomaly Crest Locations Extracted From Global Ionospheric Maps

AbstractThe Equatorial Ionization Anomaly (EIA) crest location is known to vary over a variety of temporal scales. For the first time we perform a statistical survey of the temporal variation of the EIA crest location viewed globally and spanning 20 years. We extract the crest location for double‐peaked EIAs from a data set of total electron content intensifications identified on global ionospheric maps from 2003 to 2022. We show that the dominant temporal variations of the crest latitude are annual and semi‐diurnal for the northern crest, and annual and diurnal for the southern crest. For the annual variation, we find that both crests move poleward in local summer and equatorward in local winter, which is more pronounced for the southern crest than the northern crest, and more pronounced at solar minimum than solar maximum. For the diurnal and semi‐diurnal variations in universal time, both crests dip southward around 15UT and the northern crest additionally dips southward around 2.5UT. We consider apparent universal time dependence to be a proxy for the longitudinal distribution of the crest geomagnetic latitude, which exhibits the known wave‐number‐four longitudinal structure of EIA crests. In local time, the EIA crests form earlier than 10LT and move poleward to their maximum distance at 14LT, and remain at constant latitude until 18LT. Solar cycle modulation on the diurnal/semi‐diurnal variations and the local time evolution of the crest latitude is minimal.

Thermochromic Janus Membranes with Dynamic Solar Modulation toward Sustainable and High-Efficiency Solar-to-Thermal Intelligent Management

Thermochromic Janus Membranes with Dynamic Solar Modulation toward Sustainable and High-Efficiency Solar-to-Thermal Intelligent Management

Flexible and thermoresponsive AEMR-pNIPAM/Cs0.33WO3 composite hydrogel film with NIR shielding potential for smart windows and smart curtains

Thermoresponsive flexible smart windows and smart curtains having high near-infrared (NIR) shielding and tuned visible light transmittance are essential for improving the energy efficiency of the buildings. The lower critical solution temperature (LCST) of the cross-linked poly(N-isopropylacrylamide) (pNIPAM) hydrogel film was precisely modified to a desired LCST value at 27.4 °C through the free radical copolymerization with 10 wt% of acrylated epoxidized methyl ricinoleate (AEMR). Cs0.33WO3 as NIR shielding nanoparticles (particle size < 200 nm) were synthesized via high energy ball milling method with AEMR as a surfactant for high NIR shielding efficiency and dispersion—the composite flexible hydrogel films with different wt% (0.3, 0.5,0.7, and 0.9 wt%) of Cs0.33WO3 nanoparticles were fabricated to analyze the NIR shielding efficiency and thermal insulation performance. The copolymeric hydrogel film with 0.7 wt% of Cs0.33WO3 nanoparticles (0.7-CWO) demonstrates a significant reduction in the NIR transmittance (15.0 % to 2.3 %) and variation in visible light transmittance from 73.6 % to 15.7 % while undergoing temperature-induced phase transition. The smart window fabricated with composite hydrogel film exhibits good integral luminous transmittance (Tlum, 380–780 nm, 68.7 %, below LCST) and justifiable solar modulation ability (ΔTsol, 300–2500 nm, 53.6 %). A model house was designed to monitor the indoor temperature difference, and a noticeable variation of 7 °C was observed in the house with and without 0.7-CWO film. Further, the developed composite material showed improvement in flexibility, water resistance, and thermal stability, confirming its usage for energy-saving smart windows or smart curtains.

Modulation of an Si-O-Si structure in uniformly photochromic microcapsules for solar heat and daylight management

Photochromic microcapsules adjust to sunlight adaptively and using them to fill windows is an attractive option for constructing smart windows that can manage solar heat and daylight. However, fabricating high-durability polymer-composite photochromic microcapsules for use in outdoor glass windows remains challenging, requiring high contrast ratio, high transparency, and low haze. Herein, we synthesized a novel poly(urea-siloxane) shell monomer containing Si-O-Si bonds and successfully prepared a photochromic microcapsule by modulating the mass ratios of shell monomers and emulsifiers. The photochromic poly(urea-siloxane)-based microcapsule-coated glass (PCPUS MCG) showed high luminance transmittance (83.66 %) and low haze (20.31 %). The as-prepared PCPUS MCG exhibited self-adaptive sunlight control without additional energy input, with strong solar modulation ability (Δτsol of 38.30 %). Furthermore, the response indoor air temperature was reduced by approximately 3.7 °C in a field test using a model house equipped with PCPUS MCG windows, showing promising energy-saving potential compared with conventional windows. Therefore, uniform photochromic-microcapsule modification using Si-O-Si bonds warrants attention in future energy-saving window designs.

Thermal-Rectified Gradient Porous Polymeric Film for Solar-Thermal Regulatory Cooling.

Solar-thermal regulation concerning thermal insulation and solar modulation is pivotal for cooling textiles and smart buildings.Nevertheless, a contradiction arises in balancing the demand to prevent external heat infiltration with the efficient dissipation of excess heat from enclosed spaces. Here, a concentration-gradient polymerization strategy is presented for fabricating a gradient porous polymeric film comprising interconnected polymeric microspheres. This method involves establishing an electric field-driven gradient distribution of charged crosslinkers in the precursor solution, followed by subsequent polymerization and freeze-drying processes. The resulting porous film exhibits a significant porosity gradient along its thickness, leading to exceptional unidirectional thermal insulation capabilities with a thermal rectification factor of 21%. The gradient porous film, with its thermal rectification properties, effectively reconciles the conflicting demands of diverse thermal conductivity for cooling unheated and spontaneously heated enclosed spaces. Consequently, the gradient porous film demonstrates remarkable enhancements in solar-thermal management, achieving temperature reductions of 3.0 and 4.1°C for unheated and spontaneously heated enclosed spaces, respectively, compared to uniform porous films. The developed gradient-structured porous film thus holds promise for the development of thermal-rectified materials tailored to regulate solar-thermal conditions within enclosed environments.