Intelligent Window Research Articles

Pump-Wavelength Selective All-Optical Terahertz Metasurface with Independent Amplitude and Frequency Modulations.

Tunable terahertz (THz) metasurfaces based on optical control are crucial in high-speed communication, nondestructive testing, and imaging. However, realizing independent optical tunability of multiple functions in the THz band remains challenging due to limitations in control materials. Here, we experimentally demonstrate a novel THz metasurface that employs two control materials combined with an electric-field-coupled inductor capacitor microstructure to achieve all-optical independent modulations of amplitude and frequency. Amplitude modulation is achieved through near-infrared optical pumping, reaching a maximum modulation depth of 94.42%. Broadband frequency modulation, spanning 0.21 THz, is accomplished using visible light pumping. The independent modulation function is owing to the odd-order nonlinear polarization characteristics of perovskite and the selective photon transition between the bottom Si island and the perovskite film. This work introduces a novel approach for all-optical independent modulation of THz devices, offering valuable insights for developing all-optical metasurfaces, intelligent light windows, and multidimensional ultrafast switches.

Multifunctional shape-memory smart window based on femtosecond-laser-printed photothermal microwalls

Abstract Smart windows (SWs) garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains. Apart from solar regulation, people always desire a type of slippery SW which can repel the surface hydrous contaminants for anti-fouling application. Unfortunately, the up-to-date slippery SWs that respond to electrical/thermal stimuli have drawbacks of inferior durability and high energy-consumption, which greatly constrain their practical usability. This article presents our current work on an ultra-robust and energy-efficient near-infrared-responsive smart window (NIR-SW) which can regulate the optical transmittance and droplet’s adhesion in synergy. Significantly, laser-printing strategy enables us to seed the shape-memory photothermal microwalls on a transparent substrate, which can promote daylighting while maintaining privacy by near-infrared (NIR) switching between being transparent and opaque. As a light manipulator, it turns transparent with NIR-activated erect microwalls like an open louver; however, it turns opaque with the pressure-fixed bent microwalls akin to a closed louver. Simultaneously, the droplets can easily slip on the surface of erect microwalls similar to a classical lotus effect; by contrast, the droplets will tightly pin on the surface of bent microwalls analogous to the prevalent rose effect. Owing to shape-memory effect, this optical/wettability regulation is thus reversible and reconfigurable in response to thealternate NIR/pressure trigger. Moreover, NIR-SW unfolds a superior longevity despite suffering from the raindrop’s impacting more than 10 000 cycles. Remarkably, such a new-type SW is competent for thermal management, anti-icing system, peep-proof screen, and programmable optics. This work renders impetus for the researchers striving for self-cleaning intelligent windows, energy-efficient greenhouse, and so forth.

Nonlinear LiNbO3 topological Tamm interface state photonic crystal with static visible and intelligent laser protection

The rapid advancement of high-energy laser and LiDAR technologies imposes heightened demands on intelligent laser protection windows. Traditional laser protection devices often face difficulty in simultaneously achieving high absorption of low-energy laser and high reflection of high-energy laser. Herein, we investigate the efficacy of one-dimensional nonlinear LiNbO3 topological Tamm interface state photonic crystal for static visible and intelligent laser protection applications. The photonic crystal's intelligent laser protection property arises from the amplification of nonlinear effects facilitated by the intense electric field localization surrounding the LiNbO3 interface. At 1064 nm laser energy levels below 18.29 mJ/cm2, the protection window exhibits up to 87.03% absorption. When the laser energy increased to 83.84 mJ/cm2, the reflectance reaches 88.07% attributed to the unsatisfied amplitude matching condition caused by the LiNbO3 nonlinear effect, thereby achieving successful intelligent laser protection. Furthermore, the fabricated sample demonstrates a maximum transmittance of 47.51% in the visible wavelength range. This research provides novel insights into the development of multifunctional advanced optical elements.

Reversible Antireflection Materials Inspired by Cicada Wings for Anticounterfeit and Photovoltaic Cells.

Antireflection (AR) surfaces are essential for the fields of flexible displays, photovoltaic industry, medical endoscope, intelligent windows, etc. Although natural creatures with well-organized micro/nanostructures have provided some coupling design principles for the rapid development of bioinspired AR materials, the mechanical vulnerability, poor flexibility, and nonadjustability have been pointed out as the drawback of these nanostructures. Here, a bioinspired reversible AR film with 4% reflectivity, 90% transmittance, and 9% haze in broadband (400-900 nm) was prepared. The flexible switching of AR performance enhancement and weakening throughout the visible wavelength band has been achieved by controlling the reversible change in the morphology of the interface structure. A variety of patterned film samples can be obtained by simply changing the template, which can be used in intelligent identification fields such as anticounterfeiting. The cycle test and photoelectric test show that the bionic reversible antireflection structure has certain stability and can effectively reduce the loss of photovoltaic cell conversion efficiency caused by mechanical deformation. It has broad application prospects in the fields of anticounterfeiting, intelligent window, flexible display, photoelectric element, and so on.

Four‐State Electrochromism in Tris(4‐aminophenyl)amine‐ terephthalaldehyde‐based Covalent Organic Framework

AbstractCovalent organic frameworks (COFs) are of massive interest due to their potential application spanning diverse fields such as gas storage and separation, catalysis, drug delivery systems, sensing, and organic electronics. In view of their application‐oriented quest, the field of electrochromism marked a significant stride with the reporting of the first electrochromic COF in 2019 [J. Am. Chem. Soc. 2019, 141, 19831–19838]. Since then, new and novel COF structures with electrochromic features (denoted as ecCOFs) have been searched continuously. Yet, only a handful of ecCOFs have been constructed to date. A closer look at these reports suggests that multielectrochromism (showing at least three redox color states) in a COF assembly has only been achieved once, manifested through three‐state electrochromism [Angew. Chem. 2021, 133, 12606–1261]. Herein, we report four‐state electrochromism in tris(4‐aminophenyl)amine‐terephthalaldehyde (TAPA‐PDA)‐based COF constructed through the metal‐catalyst free Schiff base approach. The four‐state (orange, pear, green, and cyan) electrochromism demonstrated by the TAPA‐PDA ecCOF opens several futuristic avenues for ecCOF′s end use in flip‐flop logic gates, intelligent windows, decorative displays, and energy‐saving devices.

Four-State Electrochromism in Tris(4-aminophenyl)amine- terephthalaldehyde-based Covalent Organic Framework.

Covalent organic frameworks (COFs) are of massive interest due to their potential application spanning diverse fields such as gas storage and separation, catalysis, drug delivery systems, sensing, and organic electronics. In view of their application-oriented quest, the field of electrochromism marked a significant stride with the reporting of the first electrochromic COF in 2019 [J. Am. Chem. Soc. 2019, 141, 19831-19838]. Since then, new and novel COF structures with electrochromic features (denoted as ecCOFs) have been searched continuously. Yet, only a handful of ecCOFs have been constructed to date. A closer look at these reports suggests that multielectrochromism (showing at least three redox color states) in a COF assembly has only been achieved once, manifested through three-state electrochromism [Angew. Chem. 2021, 133, 12606-1261]. Herein, we report four-state electrochromism in tris(4-aminophenyl)amine-terephthalaldehyde (TAPA-PDA)-based COF constructed through the metal-catalyst free Schiff base approach. The four-state (orange, pear, green, and cyan) electrochromism demonstrated by the TAPA-PDA ecCOF opens several futuristic avenues for ecCOF's end use in flip-flop logic gates, intelligent windows, decorative displays, and energy-saving devices.

The preparation of low-cost tungsten oxide films by solution-coating technique and NIR annealing for high-performance complementary electrochromic devices

Electrochromic devices can adjust their transparency by applying an electrical voltage and serve as intelligent window systems for managing incoming sunlight. In this study, we employed an environmentally friendly, large-area solution coating method to form tungsten oxide (WO3) thin films for the fabrication of electrochromic devices. We applied a WO3 precursor solution, with water as the primary solvent, onto ITO glass through blade coating and utilized near-infrared (NIR) light annealing for drying in order to rapidly optimize the film characteristics. The resulting WO3 film, combined with an ion storage layer – either sputtered NiO or blade-coated Prussian Blue (PB) - and injected with a UV-curable electrolyte, resulted in a complementary electrochromic device that exhibited good performance characteristics. For the device with NiO as the ion storage layer, the optical transmittance modulation (ΔT) can achieve 50 % at a wavelength of 680 nm, maintaining a ΔT of 45 % after 3000 coloration-bleaching cycles. For the device with PB as the ion storage layer, the ΔT achieved 64 % at 630 nm, maintaining a ΔT of 60 % after 3000 coloration-bleaching cycles. Therefore, we believe this WO3 solution coating technique combined with rapid NIR annealing technology holds promise as a low-cost and efficient method for the future production of electrochromic devices.

SOC chip based smart window curtain design

Relying on the rapid development of embedded systems, it becomes possible to integrate the system hardware into the same chip, and the system on chip SOC (System on Chips) is therefore birthed. This paper will be based on the SOC hardware and software co-design and verification, through the design of intelligent curtains for the specific implementation design of a kind of application in the al-in-one multi-functional machine motherboard design, the motherboard control core using SOC chip, integrated two MCU units, through the main control screen to display the control information to achieve the intelligent window switching conversion switching through the key such as manual mode, timer mode, light control mode. This design uses Keil as the software writing platform to realize the SOC master control system based on the on-chip bus interconnection. As well as this design can effectively reduce the degree of system cumbersomeness and provide smart window design ideas.

Design of Intelligent Window Automatic Monitoring System Based on Microcontroller Control

To ensure the safety of residents’ lives and property by using automatic opening and closing of ordinary windows, this article designs an intelligent window automatic monitoring system. The article proposes a software and hardware design scheme for the system, which comprises a microcontroller control module, temperature and humidity detection module, harmful gas detection module, rainfall detection module, human thermal radiation induction module, Organic Light-Emitting Diode (OLED) display module, stepper motor drive module, Wi-Fi communication module, etc. Users use this system to monitor environmental data such as temperature, humidity, rainfall, harmful gas concentrations, and human health. Users can control the opening and closing of windows through manual, microcontroller, and mobile application (app) remote methods, providing users with a more convenient, comfortable, and safe living environment.

Solar Window Innovations: Enhancing Building Performance through Advanced Technologies

Building-integrated photovoltaic (BIPV) glazing systems with intelligent window technologies enhance building energy efficiency by generating electricity and managing daylighting. This study explores advanced BIPV glazing, focusing on building-integrated concentrating photovoltaic (BICPV) systems. BICPV integrates concentrating optics, such as holographic films, luminescent solar concentrators (LSC), Fresnel lenses, and compound parabolic concentrators (CPCs), with photovoltaic cells. Notable results include achieving 17.9% electrical efficiency using cylindrical holographic optical elements and crystalline silicon cells at a 3.5× concentration ratio. Dielectric CPCs showed 97.7% angular acceptance efficiency in simulations and 94.4% experimentally, increasing short-circuit current and maximum power by 87.0% and 96.6%, respectively, across 0° to 85° incidence angles. Thermochromic hydrogels and thermotropic smart glazing systems demonstrated significant HVAC energy savings. Large-area 1 m2 PNIPAm-based thermotropic window outperformed conventional double glazing in Singapore. The thermotropic parallel slat transparent insulation material (TT PS-TIM) improved energy efficiency by up to 21.5% compared to double glazing in climates like London and Rome. Emerging dynamic glazing technologies combine BIPV with smart functions, balancing transparency and efficiency. Photothermally controlled methylammonium lead iodide PV windows achieved 68% visible light transmission, 11.3% power conversion efficiency, and quick switching in under 3 min. Polymer-dispersed liquid crystal smart windows provided 41–68% visible transmission with self-powered operation.

Multi-physical channels response in a novel layered perovskite: (trans-4-methylcyclohexylammonium)2[CuCl4]

With the continuous development of society, the demand for multi-physical channel responsive materials continues to increase, and it is urgent to develop multi-channel responsive materials with excellent properties. Here, in this work, we reported a novel two-dimensional (2D) organic–inorganic hybrid perovskite, (trans-4-methylcyclohexylammonium)2[CuCl4] (1), with responsive multi-physical channels. 1 experienced a structural phase transition with switchable thermochromism and dielectric response, which has great potential in the application of responsive materials. Under thermal stimulation, crystal 1 displays a reversible color variation between green and yellow. Crystal structure determination reveals that the distortion of inorganic layers plays a predominant role in the thermochromism during the phase transition process. This finding presents a compelling avenue for developing multi-physical channel responsive materials and contributes valuable insights to the exploration of two-dimensional lead-free perovskites for applications in intelligent window technology.

Anti-pollution intelligent window control system based on air detection

Anti-pollution intelligent window control system based on air detection

Smart windows with adjustable electromagnetic interference shielding using hydrogel technology

Thermochromic smart windows with adjustable electromagnetic interference (EMI) shielding capability are integral elements in modernized buildings, especially in military applications, due to their energy-saving benefits and ability to mitigate electromagnetic pollution. However, its application is limited by the relatively poor light transmission of conductive substances and the high demand for light transmission of thermochromic smart windows. Maintaining the thermochromic performance of smart windows while adjusting EMI shielding effectiveness (SE) poses a significant challenge. Here, we propose a straightforward approach to create a smart EMI shielding material with adaptable properties, including light transmission, shape, and EMI SE. This method involves a layer-by-layer polymerisation process followed by solvent substitution. The resulting hydrogel exhibits tunable optical properties, making it suitable for use as a smart window that responds to external conditions and offers local tunability. Noteworthy characteristics include high light transmittance (80.87 %), ultra-fast response time (16 s), multiple shape adjustments, adjustable EMI SE ranging from 0 to 27.64 dB, and strong adhesion, among other features. These findings suggest that the obtained hydrogels have significant potential to provide a substantial advantage in developing next-generation soft and intelligent smart EMI shielding windows.

A novel dual-functional flexible dimming film for smart window applications: Energy saving and self-cleaning performance

Polymer dispersed liquid crystal (PDLC) is a promising candidate for electrically controlled smart window applications because of its energy efficiency, convenience and other advantages. However, its flexibility and heat management capabilities are not effectively evaluated. Herein, a flexible dual-functional intelligent window based on PDLC composite is designed for this purpose, which integrates Ag nanowires as a transparent conductive electrode (TCE) and Tm3+/Yb3+-CsxWO3 (Tm3+/Yb3+-CWO) as a near-infrared shielding and air purification layer. Specifically, the as-made smart window can control the transmission of both visible and near-infrared light. Furtherly, it also possesses self-cleaning capability. A series of characterization has been carried out. The resistance of the Ag nanowire layer is measured to be 22.47 Ω/sq and the transmittance reaches 78.8 %. Flexibility test shows that when the bending radius is 4 mm, the resistance value of the TCE changes only 6 % after 500 repetitions, indicating good flexibility and stability. The spectrum examination reveals that the near-infrared light shielding efficiency achieves 80 % and the average transmittance of visible light is 76.7 %. The degradation of Rhodamine B (RhB) is used to evaluate the purification performance and result shows that the degradation percentage reaches 70 % in 120 min. Heat-regulation simulation test discloses that the indoor temperature can be decreased by 10 °C. Compared to traditional PDLC windows, the designed flexible window has broader application prospects in areas of architecture, vehicle glass, military stealth materials and so on.

Aperiodic Bragg Reflectors for Tunable High-Purity Structural Color Based on Phase Change Material.

Tunable thin-film coating-based reflective color displays have versatile applications including image sensors, camouflage devices, spatial light modulators, and intelligent windows. However, generating high-purity colors using such coatings have posed a challenge. Here, we reveal high-purity color generation using an ultralow-loss phase change material (Sb2S3)-based tunable aperiodic distributed Bragg reflector (A-DBR). By strategically adjusting the periodicity of the adjacent layers of A-DBRs, we realize a narrow photonic bandgap with high reflectivity to generate high-purity orange and yellow colors. In particular, we demonstrate an A-DBR with a large photonic bandgap tunability by changing the structural phase of Sb2S3 layers from amorphous to crystalline. Moreover, we experimentally tailor multistate tunable colors through external optical stimuli. Unlike conventional nano thin-film coatings, our proposed approach offers an irradiance-free, narrowband, and highly reflective color band, achieving exceptional color purity by effectively suppressing reflections in off-color bands.

Enhanced broadband reflection properties of PSCLCs films supported by electrospun nanofiber networks loaded with Cs0.33WO3 nanoparticles

ABSTRACT The introduction of nanoparticles into cholesteric liquid crystals has long provided inspiration for innovative device materials. A novel material design strategy was demonstrated to achieve a broadband reflection of polymer-stabilised cholesteric liquid crystals (PSCLCs) based on Cs0.33WO3 nanoparticles and the polymer nanonetworks in the PSCLCs. Through the adjustment of nanoparticle and chiral dopant (C6M) concentrations and meticulous control of polymerisation conditions, an appropriate pitch gradient distribution was achieved in the polymer-stabilised cholesteric liquid crystals (PSCLCs). This was attained by striking a delicate balance between the polymerisation speed and chiral dopant diffusion rate, resulting in optimal PSCLCs optical properties. Modification of Cs0.33WO3 nanoparticles by oleic acid was successfully accomplished as confirmed by IR spectroscopy. SEM and EDS analyses further demonstrated the distribution of nanoparticles in the spun fibre film. Moreover, POM observations showed that liquid crystals with nanofiber networks maintained the planar texture and temperature stability. The prepared broadband reflective film opens an avenue towards developing the reflection bandwidth in the PSCLCs, essential for intelligent windows and infrared shielding devices.

Fully Transparent Flexible Piezoelectric Sensing Materials Based on Electrospun PVDF and Their Device Applications

AbstractAdvanced transducer materials have become increasingly important with the rapid development of the internet of things and flexible electronics. Herein, fully transparent flexible polyvinylidene fluoride/polydimethylsiloxane (PVDF/PDMS) composite piezoelectric films are fabricated using scrape coating techniques based on electrospun PVDF nanofiber films. Compared to the electrospun PVDF, the PVDF/PDMS not only owns high transparency and a more uniform and stable structure but also has superior piezoelectric properties. Based on the electrospun PVDF and the PVDF/PDMS films, flexible piezoelectric sensors are developed, which can effectively detect weak mechanical signals including finger tapping and bending signals, radial artery pulses, and environmental sound signals. The PVDF/PDMS sensor performs better than the electrospun PVDF sensor and presents great potential for applications in flexible sensors and transducers. Especially, thanks to their high transparency, the PVDF/PDMS composite piezoelectric films lend themselves easily to application fields requiring transparent sensors such as imperceptible sensors and human‐machine interfaces, display devices, electronic skins, intelligent windows, etc.

Dual response multi-function smart window: An integrated system of thermochromic hydrogel and thermoelectric power generation module for simultaneous temperature regulation and power generation

Thermochromic smart windows have the capability to intelligently adjust color and light transmission based on ambient temperature and light levels, attracting considerable attention due to their potential to enhance building energy efficiency and residential comfort. However, excessive sunlight exposure can lead to increased heat generation, potentially affecting the service life of the window. In this work, we present the development of an efficient intelligent solar thermal utilization window, incorporating heat collection, temperature regulation, and power generation functionalities. The smart window achieves light modulation by adjusting the glycerol content in the thermochromic hydrogel. In addition, the thermoelectric material is arranged in series and parallel to the smart window functioning as the power generation module. The developed smart window shows excellent sunlight modulation capability (91.2 % visible light transmittance and 99.2 % sunlight shielding rate). Meanwhile, the response temperature of the window can be adjusted from 34.5 °C to 29 °C. The thermoelectric hydrogel can generate continuous and stable current (∼75 µA) with a temperature difference of 40 ℃. The practical application proves that the generated power by the temperature difference can fully meet the switching needs of small electrical appliances. This transformation framework between photothermal-electricity conversion deserves attention in the design of future smart windows.

Broadband High Optical Transparent Intelligent Metasurface for Adaptive Electromagnetic Wave Manipulation.

Intelligent metasurfaces have garnered widespread attention owing to their properties of sensing electromagnetic (EM) environments and multifunctional adaptive EM wave manipulation. However, intelligent metasurfaces with broadband high optical transparency have not been studied to date, and most of the previous intelligent metasurfaces lack an integrated design for their actuators and sensors, resulting in lower integration levels. This study proposes a novel intelligent metasurface with adaptive EM wave manipulation ability and high optical transparency from visible to infrared bands. This metasurface consists of a transparent and current-controlled reconfigurable metasurface as an actuator by integrating patterned vanadium dioxide (VO2) into metal-meshed resonant units, transparent broadband microstrip antenna as a sensor, recognition-and-feedback module, and actuator- and sensor-integrated design on the same substrate. The EM-regulating capability of the designed transparent intelligent metasurface is theoretically analyzed using the coupled mode theory, and a prototype metasurface device is fabricated for experimental verification. Simulation and experimental results demonstrate that the metasurface exhibits over 80% normalized transmittance from 380 to 5,000 nm and adaptive EM wave manipulation (reflective strong shielding function with a shielding efficiency of over 24 dB, high transmittance function with a transmission loss of 1.24 dB, and strong absorption function with an absorption of 97%) according to the EM wave power parameters without manual intervention. This study provides an avenue for transparent intelligent metasurfaces with extensive application prospects in areas such as intelligent optical windows, radar enclosures, and communication.

Silver reversible electrodeposition device under −40 °C condition

Silver reversible electrodeposition devices (SREDs) find wide applications in intelligent windows, automobiles, intelligent displays, and other fields. They can achieve a mirror state close to 100% reflectance and generate plasmon phenomena of different colors by controlling the driving voltage. However, the switchability of these devices is compromised below 0 °C due to the molecular properties of the solvent dimethyl sulfoxide (DMSO), making it impossible to work in severe cold areas. This work has discovered a solvent called N-methylpyrrolidone (NMP), which possesses weak intermolecular forces, low dipolarity, and high solubility. By developing a SRED using NMP as the solvent, we have achieved a lower opening voltage at room temperature compared to the DMSO system. This is advantageous for the preparation of large-area devices. Additionally, the NMP system device retains its switching ability even under extreme conditions of −40 °C, freezing only when temperatures reach −43 °C, which is currently the lowest reported SRED operating temperature. This breakthrough brings us closer to the practicality of SRED.