Explore the vast range of titles available.

Advanced constructive materials, such as electrochromic smart windows (ECSWs) and building integrated photovoltaics modules (BIPV), can improve the energy efficiency in buildings. A good optical and thermal characterization of these elements is necessary to assess and compare their performance. The existing testing procedures for glass in buildings are applied to both types of elements, and it is considered that while the optical procedures are suitable and allow good comparison of the two technologies, the indoor thermal testing procedures are not valid for BIPV nor ECSWs, because temperature of these absorbing elements strongly depend on the irradiance, something not considered in the current standards. To show and characterize this dependence, simultaneously monitoring of different photovoltaics (PV) modules and electrochromic windows has been performed outdoors under solar irradiance. A relationship between the surface temperature, the irradiance, and the ambient temperature has been obtained for each sample to compare both technologies.

HighlightsTransition metal phosphates were first developed for the electrochromic application.The obtained NiHPO4·3H2O film achieves an ultra-large optical modulation of 90.8%, and the electrochromic mechanism is systematically elucidated using in situ and ex situ techniques.A large-area electrochromic smart window with 100 cm2 is constructed, which displays superior performances in regulating natural lighting and storing electrical charges.Exploring materials with high electrochemical activity is of keen interest for electrochemistry-controlled optical and energy storage devices. However, it remains a great challenge for transition metal oxides to meet this feature due to their low electron conductivity and insufficient reaction sites. Here, we propose a type of transition metal phosphate (NiHPO4·3H2O, NHP) by a facile and scalable electrodeposition method, which can achieve the capability of efficient ion accommodation and injection/extraction for electrochromic energy storage applications. Specifically, the NHP film with an ultra-high transmittance (approach to 100%) achieves a large optical modulation (90.8% at 500 nm), high coloration efficiency (75.4 cm2 C−1 at 500 nm), and a high specific capacity of 47.8 mAh g−1 at 0.4 A g−1. Furthermore, the transformation mechanism of NHP upon electrochemical reaction is systematically elucidated using in situ and ex situ techniques. Ultimately, a large-area electrochromic smart window with 100 cm2 is constructed based on the NHP electrode, displaying superior electrochromic energy storage performance in regulating natural light and storing electrical charges. Our findings may open up new strategies for developing advanced electrochromic energy storage materials and smart windows.

Building energy consumption accounts for 20%-40% of global energy usage, with windows among the least energy-efficient components. For this issue, thermochromic smart windows have emerged as a cost-effective, stimuli-responsive approach to enhance building energy performance. However, achieving long-term improvements in the indoor lighting environment remains a significant challenge for this technology. In this work, we developed a dual-responsive hydrogel that combines photochromic and thermochromic functionalities, exhibiting excellent shrinkage resistance, tunable spectral characteristics, and robust color-changing behavior. By integrating these hydrogels with solar selective and indium tin oxide films, we designed a tri-band regulation smart window featuring asymmetric mid-infrared emissivity, capable of simultaneously managing visible and near-infrared light to effectively reduce indoor heat gain and loss. The resulting smart window demonstrated superior spectral performance, with a solar modulation rate (ΔT ) of 40.8%, visible light modulation (ΔT ) of 61.4%, near-infrared blocking of 71.7%, and an emissivity contrast between the inner and outer surfaces (Δε) of 66%. These outstanding properties translate into annual energy savings of 14.2%-24.4% for curtain wall buildings globally, excluding polar regions. The concept of tri-band dual-response regulation significantly enhances the energy saving potential of smart windows and broadens their prospects for practical application.

Smart windows with tunable optical properties that respond to external environments are being developed to reduce energy consumption in buildings. In the present study, we introduce a new type of 3D printed hydrogel with amazing flexibility and stretchability (as large as 1500%), as well as tunable optical performance controlled by surrounding temperatures. The hydrogel on a PDMS substrate shows transparent-opaque transition with high solar modulation (Δ T sol ) up to 79.332% around its lower critical solution temperature (LCST) while maintaining a high luminous transmittance ( T lum ) of 85.847% at 20 °C. In addition, selective transparent-opaque transition above LCST can be achieved by patterned hydrogels which are precisely fabricated via a projection micro-stereolithography based 3D printing technique. Our hydrogel promises great potential applications for the next generation of soft smart windows.

Electrochromic smart windows have attracted much attention in energy-saving buildings because of their ability to selectively modulate visible (VIS) and near-infrared (NIR) light transmittance. As is known, the NIR region accounts for about 50% of the total solar radiation. Therefore, reducing the NIR transmittance of windows will play a crucial role in reducing the energy consumption of buildings. However, for most of the reported electrochromic materials (ECMs)-based windows, it remains a long-lasting challenge about how to achieve a low NIR transmittance during the past decades. In this work, we synthesize oxygen-deficient tungsten oxide (WO 3− x ) nanoflowers (NFs) by a simple and efficient method that is facile for their mass production. The WO 3− x NFs exhibit low NIR transmittance of only 4.11%, 0.60%, and 0.19% at 1200, 1600, and 1800 nm, respectively, due to the localized surface plasmon resonance (LSPR) effect. Besides, the WO 3− x NFs exhibit an excellent dual-band modulating ability for both VIS and NIR light. They are able to operate in three distinct modes, including a bright mode, a cool mode, and a dark mode. Moreover, the WO 3− x NFs exhibit a fast bleaching/coloring time (1.54/6.67 s), and excellent cycling stability (97.75% of capacity retention after 4000 s).

In the context of sustainability and in the face of ambitious goals towards the reduction of CO2 emission, the modification of transparency in architecture becomes an important tool of energy flow management into the building. Windows that dim to stop the energy transfer reduce the cooling load in the building. Recently, however, the latest achievements in the development of electrochromic materials allowed us to integrate some additional—previously unknown—functionalities into EC devices. The purpose of this paper is to provide a systematic review of recent technological innovations in the field of smart windows and present the possibilities of recently established functionalities. This review article outlines recent general progress in electrochromic but concentrates on multicolour and neutral black electrochromism, spectrally selective systems, electrochromic energy storage windows, hybrid EC/TC systems, OLED lighting integrated with the EC device, and EC devices powered by solar cells. The review was based on the most recent publication from the years 2015–2020 recorded in the databases WoS and Scopus.

Thermochromic smart windows technology can intelligently regulate indoor solar radiation by changing indoor light transmittance in response to thermal stimulation, thus reducing energy consumption of the building. In recent years, with the development of new energy-saving materials and the combination with practical technology, energy-saving smart windows technology has received more and more attention from scientific research. Based on the summary of thermochromic smart windows by Yi Long research groups, this review described the applications of thermal responsive organic materials in smart windows, including poly(N-isopropylacrylamide) (PNIPAm) hydrogels, hydroxypropyl cellulose (HPC) hydrogels, ionic liquids and liquid crystals. Besides, the mechanism of various organic materials and the properties of functional materials were also introduced. Finally, opportunities and challenges relating to thermochromic smart windows and prospects for future development are discussed.

Windows are the least energy efficient part of the buildings, as building accounts for 40% of global energy consumption. Traditional smart windows can only regulate solar transmission, while all the solar energy on the window is wasted. Here, for the first time, the authors demonstrate an energy saving and energy generation integrated smart window (ESEG smart window) in a simple way by combining louver structure solar cell, thermotropic hydrogel, and indium tin oxides (ITO) glass. The ESEG smart window can achieve excellent optical properties with ≈90% luminous transmission and ≈54% solar modulation, which endows excellent energy saving performance. The outstanding photoelectric conversion efficiency (18.24%) of silicon solar cells with louver structure gives the smart window excellent energy generation ability, which is more than 100% higher than previously reported energy generation smart window. In addition, the solar cell can provide electricity to for ITO glass to turn the transmittance of hydrogel actively, as well as the effect of antifreezing. This work offers an insight into the design and preparation together with a disruptive strategy of easy fabrication, good uniformity, and scalability, which opens a new avenue to realize energy storage, energy saving, active control, and antifreezing integration in one device. The authors develop a revolutionary smart window with a multi‐layer louver structure, containing a silicon solar cell, thermotropic hydrogel, and ITO active layer, which combine both an energy saving and energy generation ability (ESEG smart window) with leverages high solar energy modulation together with high photoelectric conversion efficiency (PCE).

Liquid crystal (LC) smart windows that are able to regulate natural light by changing the optical transmittance in response to external stimulus have become an effective way to reduce building energy consumption. The rapid development of technology has brought out a variety of responsive smart windows suitable for daily life, including electrical-, thermal-, and photo-responsive ones. In this review, the recent progress in LC smart windows that switch between transparent and opaque states by different stimuli is overviewed. The preparation strategies for single-/dual-responsive smart windows are outlined, exclusively concentrating on the functional design and working principle. Furthermore, the advantages and current drawbacks of smart windows for each response mode are briefly described. Finally, a perspective on the direction of future responsive LC smart windows is discussed.

Dimming and scattering control are two of the major features of smart windows, which provide adjustable sunlight intensity and protect the privacy of people in a building. A hybrid photo- and electrical-controllable smart window that exploits salt and photochromic dichroic dye-doped cholesteric liquid crystal was developed. The photochromic dichroic dye causes a change in transmittance from high to low upon exposure to sunlight. When the light source is removed, the smart window returns from colored to colorless. The salt-doped cholesteric liquid crystal can be bi-stably switched from transparent into the scattering state by a low-frequency voltage pulse and switched back to its transparent state by a high-frequency voltage pulse. In its operating mode, an LC smart window can be passively dimmed by sunlight and the haze can be actively controlled by applying an electrical field to it; it therefore exhibits four optical states—transparent, scattering, dark clear, and dark opaque. Each state is stable in the absence of an applied voltage. This smart window can automatically dim when the sunlight gets stronger, and according to user needs, actively adjust the haze to achieve privacy protection.