Sol-gel-based porous Ti-doped tungsten oxide films for high-performance dual-band electrochromic smart windows

Dual-band electrochromic smart windows(DESWs)with independent control of the transmittance of near-infrared and visible light show great potential in the application of smart and energy-saving buildings.The current strategy for building DESWs is to screen materials for composite or prepare plasmonic nanocrystal films.These rigorous preparation processes seriously limit the further development of DESWs.Herein,we report a facile and effective sol-gel strategy using a foaming agent to achieve porous Ti-doped tungsten oxide film for the high performance of DESWs.The introduction of foaming agent polyvinylpyrrolidone during the film preparation can increase the specific surface area and free carrier concentration of the films and enhance their independent regulation ability of near-infrared electrochromism.As a result,the optimal film shows excellent dual-band electrochromic properties,including high optical modulation(84.9%at 633 nm and 90.3%at 1200 nm),high coloration efficiency(114.9 cm^(2) C^(-1) at 633 nm and 420.3 cm^(2) C^(-1) at 1200 nm),quick switching time,excellent bistability,and good cycle stability(the transmittance modulation losses at 633 and 1200 nm were 11%and 3.5%respectively after 1000 cycles).A demonstrated DESW fabricated by the sol-gel film showed effective management of heat and light of sunlight.This study represents a significant advance in the preparation of dual-band electrochromic films,which will shed new light on advancing electrochromic technology for future energy-saving smart buildings.

Novel self-assembled porous yolk-shell NiO nanospheres with excellent electrochromic performance for smart windows

With the rapid development of optoelectronics,electrochromic(EC)materials(ECMs)with the advan-tages of low power consumption,easy viewing,high contrast ratio,etc have attached more and more attention from the fields of smart windows,electronic billboards,emerging wearable and portable electronics,and other next-generation displays.Nickel oxide(NiO)is a promising candidate for high-performance ECMs because of its neutral-colored states and low cost.However,NiO-based ECMs still face the problem of slow switching speed due to their low electrical conductivity and small lattice spacing.Metal-organic frameworks(MOFs)are promising candidates to fabricate hollow and porous transition metal oxides(TMOs)with high ion transport efficiency,excellent specific capacitance,and electrochemical activities.In this work,porous yolk-shell NiO nanospheres(PYS-NiO NSs)were syn-thesized via a solvothermal and subsequent calcination process of Ni-MOF,which exhibited outstanding EC performance.Because the large specific surface areas and hollow porous nanostructures were conducive to ionic transport,PYS-NiO NSs exhibited a fast coloring/bleaching speed(3.6/3.9 s per one coloring/bleaching cycle)and excellent cycling stability(82%of capacity retention after 3000 cycles).These superior EC properties indicated that the PYS-NiO NSs was a promising candidate for high-performance EC devices.This work provides a new and feasible strategy for the efficient preparation of TMOs ECMs with good EC performance,especially fast switching speed.

An overview and experimental analysis of WO_(3)/TiO_(2)composite with enhanced electrochromic properties for smart windows application

Internationally,standards for electrochromic(EC)requirements in smart window applications have been established,with ongoing global initiatives aimed at elevating them to highly advanced levels.This paper covers a comprehensive investigation of the structural,optical,morphological,and electrochemical properties of WO_(3)/TiO_(2)composite films.Simultaneously,an experimental analysis of WO_(3)/TiO_(2)was envisaged by a two-step process.Initially,WO_(3)thin films were hydrothermally deposited onto indium-doped tin oxide-coated glass substrates using an aqueous solution of Na_(2)WO_(4)·2H_(2)O at a pH value of 1.Subsequently,a layer of TiO_(2)was electrodeposited onto the WO_(3)thin films.X-ray diffraction analysis confirmed the successful formation of WO_(3)/TiO_(2)composite films,with the WO_(3)phase exhibiting a hexagonal tunnel structure.Scanning electron microscopy revealed the formation of porous nanorods(NRs)of WO_(3),uniformly coated with TiO_(2),resulting in a porous morphology of the WO./TiO_(2)samples.The EC performance of the WO_(3)/TiO_(2)films was thoroughly assessed through cyclic voltammetry and chronoamperometry measurements over a potential window ranging from-2.0 to+1.2 V(versus Ag/AgCl)in a 0.5 mol·L^(-1)LiClO_(4)-PC electrolyte.The WO_(3)/TiO_(2)composite films exhibited cathodic electrochromism,characterized by a reversible color change from dark blue to transparent.This improved EC performance in comparison to pure WO_(3)films is attributed to enhanced double ion/electron insertion and extraction efficiency.Furthermore,the WO_(3)/TiO_(2)composite films demonstrated excellent optical modulation properties,with a significant modulation at 633 nm(46.87%).The coloration efficiency reached a high value of 193.25 cm^(2)·C^(-1),indicating their potential for practical EC applications.Moreover,the WO_(3)/TiO_(2)composite films displayed exceptional EC stability,with no significant degradation observed over 2500 cyclic voltammetry cycles.This superior EC performance can be attributed to the synergistic effect between the hexagonal WO_(3)NRs and anatase TiO_(2).This study highlights the significance of the synthesis method and the unique structural characteristics of the composite in enhancing the EC performance.

Reversible Zn^(2+) Insertion in Tungsten Ion-Activated Titanium Dioxide Nanocrystals for Electrochromic Windows

Zinc-anode-based electrochromic devices(ZECDs) are emerging as the next-generation energy-e cient transparent electronics. We report anatase W-doped TiO_(2) nanocrystals(NCs) as a Zn^(2+) active electrochromic material. It demonstrates that the W doping in TiO_(2) highly reduces the Zn^(2+) intercalation energy,thus triggering the electrochromism. The prototype ZECDs based on W-doped TiO_(2) NCs deliver a high optical modulation(66% at 550 nm),fast spectral response times(9/2.7 s at 550 nm for coloration/bleaching),and good electrochemical stability(8.2% optical modulation loss after 1000 cycles).

An Electrochromic Nickel Phosphate Film for Large-Area Smart Window with Ultra-Large Optical Modulation

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(NiHPO_(4)·3H_(2)O,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 cm^(2)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 cm^(2)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.

Oxygen-deficient tungsten oxide nanoflowers for dynamically tunable near-infrared light transmittance of 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 longlasting challenge about how to achieve a low NIR transmittance during the past decades.In this work,we synthesize oxygendeficient 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).

An all solid-state electrochromic smart window

An all solid-state electrochromic smart window employing prussian blue and electrodeposited WO-3 film with poly (vinyl chloride) (PVC) gel electrolyte that has high conductivity (2 mS/cm) at room temperature has been fabricated for the first time. The smart window has been found to be excellent for electrochromism and memory characteristics.

Active and passive modulation of solar light transmittance in a uniquely multifunctional dual-band single molecule for smart window applications

Functional materials may change color by heat and electricity separately or simultaneously in smart windows.These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of life.Unfortunately,dual-responsive materials have not received ample research attention due to economic and technological challenges.As a consequence,the broader utilization of smart windows faces hindrances.To address this new generational multistimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(NIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(NIPAM)n-based smart material for better utility and activity.These constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(thermochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(electrochromic)states.Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance.Each unique chromic mode operates independently and modulates visible and near-infrared(NIR)light in a distinct manner.Hence,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.

Recent progress in Prussian blue electrode for electrochromic devices

Great progress has been made in the electrochromic(EC)technology with potential applications in various fields.As one of the most promising EC materials,Prussian blue(PB)has attracted great attention due to its excellent EC performance,such as low cost,easy synthesis,rich color states,chemical stability,suitable redox potential,and fast color-switching kinetics.This review summarizes the recent progress in PB electrodes and devices,including several typical preparation techniques of PB electrodes,as well as the recent key strategies for enhancing EC performance of PB electrodes.Specifically,PB-based electrochromic devices(ECDs)have been widely used in various fields,such as smart windows,electrochromic energy storage devices(EESDs),wearable electronics,smart displays,military camouflage,and other fields.Several opportunities and obstacles are suggested for advancing the development of PB-based ECDs.This comprehensive review is expected to offer valuable insights for the design and fabrication of sophisticated PBbased ECDs,enabling their practical integration into realworld applications.

电色smart窗

综述了电色smart窗的由来、设计准则、窗的基本结构。介绍了组成窗的各层膜特性，某些试制型窗的实例、还探讨了电色开关窗器件的耐久性问题。

MgF_(2) as abundant and environmentally friendly electrolytes for high performance electrochromic devices

Electrochromic devices(ECDs)can regulate the indoor solar radiation by adjusting optical transmissive properties,showing great commercial potential and important social value of green energy saving.However,the unsafety and high cost of Li^(+) based electrolyte hinder the large-scale and industrialized production of ECDs.Other metal ions have been used as electrolyte ions,but they are rarely reported in all solid state ECDs.In this study,MgF_(2) film is used as the solid electrolyte to construct all solid state ECD with the structure of glass/ITO/WO_(3)/MgF_(2)/NiO/ITO.The ECD shows the large optical modulation(~83%at 820 nm,with 100 s durations)and fast response(19.2 s for bleaching and 8.3 s for coloring,with 25 s durations).Moreover,the ECD achieves the extreme transmittance value of colored states Tc=0%,which can give an absolute private state.This work not only indicates that MgF_(2) film can be an alternative to Lit based electrolyte in all solid state ECDs,but also broadens the applications of all solid state EC smart windows to private buildings.

Laminated all-solid state NiO/WO_3 complementary electrochromic device

Based on the previous studies on the rf reactive sputtered nickel oxide film with nanostructure and its electrochromism, i. e. electrochromic effect of the films is attributed to the reversible change of the non-stoichiometry in the nanocrystaltine gram boundaries and interfaces due to the injection and ejection of Li+ ions, a prototype of all-solid-state NiO/WO3 complementary electrochromic device using LixTaOy thin film as inorganic electrolyte was designed and prepared. The results indicate that the solar reflectance of the device could be modulated from 0. 15 in colored state to 0.60 in bleached state with excellent cyclic reversibility, durability and high response speed (less than 0.3 s from colored state to bleached state).

高分子凝胶电解质及其在电色Smart窗中的应用

研究了高分子凝胶电解质高氯酸锂－碳酸丙烯酯－聚甲基丙烯酸甲酯体系（ＬｉＣｌＯ４－ＰＣ－ＰＭＭＡ）的离子导电性、导电机理以及在电色Ｓｍａｒｔ窗中的应用．其离子电导率与温度的关系服从Ｖｏｇｅｌ－Ｔａｍｍａｎｎ－Ｆｕｌｃｈｅｒ方程，并与体系的ＰＭＭＡ质量百分数、玻璃化温度（Ｔｇ）、碱金属盐的浓度等有关．当ＬｉＣｌＯ４浓度为０．５ｍｏｌ／Ｌ，ＰＭＭＡ＝３５％时，电解质具有良好的粘附性、光学透明度及较高的室温离子电导率（σ＝８．７５×１０－４Ｓ／ｃｍ）．由其组装成的全固态电色Ｓｍａｒｔ窗具有良好的光谱特性，可见光调制范围为４０％～６０％；具有良好的光开关特性，响应时间仅为５ｓ．

CaF_(2):A novel electrolyte for all solid-state electrochromic devices

The energy consumption in building ventilation,air,and heating conditioning systems,accounts for about 25%of the overall energy consumption in modern society.Therefore,cutting carbon emissions and reducing energy consumption is a growing priority in building construction.Electrochromic devices(ECDs)are considered to be a highly promising energy-saving technology,due to their simple structure,active control,and low energy input characteristics.At present,Hþ,OH-and Liþare the main electrolyte ions used for ECDs.However,Hþand OH-based electrolytes have a high erosive effect on the material surface and have a relatively short lifetime.Liþ-based electrolytes are limited due to their high cost and safety concerns.In this study,inspired by prior research on Ca^(2+)þbatteries and supercapacitors,CaF_(2)films were prepared by electron beam evaporation as a Ca^(2+)þ-based electrolyte layer to construct ECDs.The structure,morphology,and optical properties of CaF_(2)films were characterized.ECDs with the structure of ITO(indium tin oxide)glass/WO3/CaF_(2)/NiO/ITO show short switching times(22.8 s for the coloring process,2.8 s for the bleaching process).Additionally,optical modulation of the ECDs is about 38.8%at 750 nm.These findings indicate that Ca^(2+)þbased ECDs have the potential to become a competitive and attractive choice for large-scale commercial smart windows.

热电双响应智能窗的研究进展

近年来,能源危机日益加重,人们在节能方面做出了许多努力,其中智能窗作为一种节能产品备受青睐。本文主要对目前具有热电双响应性能的智能窗的研究现状进行了综述,可将其大概分为有机型、无机型以及有机-无机复合型。研究者们将具有热致变色和电致变色的材料进行复合,使二者的特性有机地结合起来,并将其做成器件后展示出优异的热电双响应性能,为多重刺激响应智能窗的开发奠定了一定的基础,提供了大致研究的方向和思路。在文章最后做出总结,指出现存的一些问题并进行了展望。

化学气相沉积法制备智能窗用热致变色VO_(2)薄膜的研究进展

热致变色智能窗是通过在玻璃上沉积温度刺激响应型材料,实现根据环境温度调控窗户玻璃的太阳光透过率,减少建筑物能耗的节能窗户。二氧化钒(VO_(2))是一种典型的热致相变材料,在~68℃发生金属-绝缘体相变,相变前后伴随光学性能的显著变化,在智能窗等多个领域有潜在的技术应用。然而,当前VO_(2)基热致变色智能窗的应用仍存在着相变温度(τc)偏高、可见光透过率(Tlum)低和太阳能调节效率(ΔTsol)不足等问题,无法满足实际建筑节能的需求。为了解决这些问题,研究人员开展了广泛而深入的工作。化学气相沉积法(Chemical vapor deposition,CVD)能够以合理的成本生产高质量、大面积的VO_(2)薄膜,受到研究者青睐。本文总结了近年来利用CVD技术制备VO_(2)薄膜的研究进展,系统介绍常压化学气相沉积、气溶胶辅助化学气相沉积、低压化学气相沉积、金属有机物化学气相沉积、原子层沉积和等离子体增强化学气相沉积等CVD工艺,分析了反应物种类及比例、反应温度、压力、载体流量等因素对VO_(2)薄膜质量的影响,并结合元素掺杂、纳米复合薄膜、多层膜结构等对VO_(2)薄膜的性能调控与优化进行总结,最后对未来等离子体增强化学气相沉积制备VO_(2)薄膜的研究前景做出展望。

透明建筑围护结构太阳得热动态可调的新型薄膜材料

广泛采用的低辐射(Low-E)镀膜玻璃窗节能效果良好,但不具备太阳得热动态调节功能。相比于太阳得热静态不可调窗,在制冷季低得热、采暖季高得热的智能可调透明围护结构更加节能。介绍了一种在聚二甲基硅氧烷弹性体上镶嵌3层纳米功能层的膜材料,可用于制备太阳得热可智能动态调节的透明建筑围护结构,提高建筑节能与舒适性。智能动态调节膜可以实现直接的太阳透射率调节。通过建筑能耗模拟证实,由该智能动态调节膜制备的智能窗对比传统的太阳得热静态不可调窗,在全国范围内可实现2.4%~13.8%的暖通空调系统节能。

电致变色材料及应用

在介绍电致变色器件结构的基础上讨论了传统和新出现的变色材料及其变色原理，并对电致变色机理的主要模型作了概括。

电致变色材料及器件的研究进展

电致变色材料被认为是目前最有应用前景的智能材料之一,在过去几十年里被广泛研究,相关的电致变色器件也已经上市。本文在总结了各种电致变色材料的变色机理及其成膜方法(重点介绍了本实验室采用射频溅射制备的WO3膜和NiOx膜)的基础上,研究了材料的应用及器件的组装,并对器件组装中所需要的部分其它关键材料进行了介绍。最后对未来电致变色材料及其应用进行了展望。