Journal of Inorganic Materials-Channel: TOPLCAL SECTION Channel: TOPLCAL SECTION http://www.jim.org.cn EN-US http://www.jim.org.cn/EN/1000-324X/current.shtml http://www.jim.org.cn 1000-324X <![CDATA[Molybdenum Oxide Electrochromic Materials and Devices]]> http://www.jim.org.cn/EN/10.15541/jim20200416 Electrochromic materials show reversible color-changeable characteristics, which are widely used in smart windows, displays, adjustable reflective mirrors, electronic paper, military camouflage and other fields. Compared with other kinds of display devices, electrochromic display devices have advantages of multi-colors, high contrast, no blind visual angles, and maintainable color after power off. As a typical cathodic colored electrochromic material, molybdenum oxide exhibits advantages of short response time and colored state closer to the sensitive wavelength band of the human eye to light, so that the electrochromic devices composed of molybdenum oxide is important in the research. This paper briefly introduces the definitions and applications of electrochromism, electrochromic materials and devices. In particular, electrochromic technology recently realized a demonstration application in smart phones, indicating the good prospects for the future development of electrochromic technology. We summarized mainly the research progress of the preparation of molybdenum oxide films, the modification of molybdenum oxide, and the molybdenum oxide based electrochromic devices. Finally, we presented current existing problems and solutions on molybdenum oxide based electrochromic films and devices with development prospects.

]]> <![CDATA[Reflective Property of Inorganic Electrochromic Materials]]> http://www.jim.org.cn/EN/10.15541/jim20200465 Optical property, such as color, transmittance, reflectance and emissivity, of electrochromic materials can be changed reversibly under low applied voltages. Electrochromic materials have a wide range of regulatable spectrum, which can realize the broadband control from the visible to mid-far-infrared. Electrochromic materials show a wide application prospect in the fields of intelligent window, display, anti-glare rearview mirror, intelligent thermal control, and camouflage. At present, most of researches on inorganic electrochromic materials focus mainly on transmission characteristics, but less on reflection characteristics. This is mainly because most inorganic electrochromic materials have single color and are not as easy to design as organic electrochromic materials. In recent years, through special preparation and structural design, the research on reflective properties of inorganic electrochromic materials has gradually attracted researchers鈥� attention. Based on reflection characteristics of inorganic electrochromic materials, methods and principles of regulating the reflectance spectrum in the visible near infrared to mid-far-infrared bands are introduced, and the latest research progress is summarized. Within the visible band, reflectance spectrum control is mainly achieved by vanadium pentoxide (V2O5) and V2O5 doping, microstructure of one dimensional photonic crystal, Fabry Perot nanocavity structure and localized surface plasmon resonance (LSPR). Within the mid-to-far infrared band, electrochromic devices (ECDs) based on the molecular vibration absorption of tungsten oxide (WO3) or other electrochromic materials and related theory are designed and fabricated to regulate reflectance spectra. Finally, the practical application of inorganic electrochromic materials in future is prospected.

]]> <![CDATA[Infrared Electrochromic Property of the Colorful Tungsten Oxide Films]]> http://www.jim.org.cn/EN/10.15541/jim20200463 Electrochromic materials are capable in a dynamically modulation over their absorption, transmission, reflection and emissivity covering the visible and infrared regions, which is recognized as one of the most effective strategies for an artificial control over the optical spectrum. In practical devices, the modulations for color (visible light) and heat (near-infrared irradiation) are both in demand, and thus it is of significant importance to achieve the dual-band control within single electrochromic device. However, the present design of electrochromic materials mainly focuses on the adjustment ability of visible spectrum or color transformation, while leaving the modulation of infrared spectra often negligible. In this study, a multi-color tungsten oxide film with F-P cavity structure is selected to explore the wide-spectrum electrochromism of visible and infrared spectral regions. The tungsten oxide film material with F-P cavity structure presents diversified and bright colors in the visible region with various color patterns, and diversified color alternation can be realized under applied biases. At the same time, the infrared reflectance of colorful tungsten oxide films can also be modulated significantly, for example, infrared modulation rates higher than 25.00% can be obtained in the middle wavelength (around 3.5 渭m) in the colored films. The research shows that the multi-color tungsten oxide film can realize the discrete and controllable adjustment of the visible and infrared spectral region in the wide spectrum, and has great potential in the application of smart window, thermal management, radiative cooling and other fields, which can even achieve the in-demand cooperative modulation of light and heat performance.

]]> <![CDATA[Preparation of Lithium Titanate Thin Film for Electrochromic Smart Window by Sol-Gel Spin Coating Method]]> http://www.jim.org.cn/EN/10.15541/jim20200584 Electrochromic materials are attractive for applications like smart windows and thermal management which can modulate transmittance from visible to near-infrared wavelengths. Lithium titanate has been proven to be a potential electrochromic cathode material, but its application prospects in the field of smart windows still lack data support. In this work, Li4Ti5O12 thin films with high transmittance and good crystallinity were prepared by Sol-Gel spin coating. The electrochromic properties of the films were characterized by different methods. It is found that all Li4Ti5O12 thin films are very sensitive to the test conditions, such as scanning rate, displaying excellent dual band modulation property. Also, the thickness has a significant effect on the initial state transmittance, modulation amplitude, response time, voltage window and cycle durability of the Li4Ti5O12 thin films. The colored and bleached response time of the 450 nm Li4Ti5O12 is 19.1 and 8.9 s, respectively, while the transmittance modulation is 45% in the visible light region (550 nm). The performance of the films have not been significantly degraded after 20000 s continuous cycle. It is worth mentioning that the transmittance modulation in the near infrared band (1000 nm) is as high as 80%, showing excellent energy saving potential. Finally, Glass/FTO/Li4Ti5O12/LiNbO3/NiOx/ITO, an all-solid-state inorganic electrochromic device with good cycle performance from gray to blue was successfully assembled. Above data demonstrate that lithium titanate is a strong competitive material for the popularization of electrochromic smart window.

]]> <![CDATA[Sandwich Structured Electrolyte of High Sputtering Efficiency for All-solid-state Electrochromic Devices by Optical Design]]> http://www.jim.org.cn/EN/10.15541/jim20200633 The all-solid-state electrochromic devices (ECDs) have been widely developed for energy-saving windows, screen displays, multi-functional energy storage devices due to their characteristics such as large optical contrast, fast switching speed and good cycle stability. However, traditional all-solid-state ECDs based on monolayer electrolyte system are often limited by ordinary optical transmittance and inadequate sputtering efficiency. Herein, the all-solid- state ECDs integrated with LiAlOx/Ta2O5/LiAlOx (ATA) sandwich structured electrolyte were successfully fabricated by reactive DC magnetron sputtering technique. By means of introduction of ATA sandwich structured electrolyte, the prepared ECDs with seven layer (ITO/NiO/LiAlOx/Ta2O5/LiAlOx/WO3/ITO) was endowed with superfine optical transmittance and substantial sputtering efficiency simultaneously. The ATA-based ECDs realized satisfactory coloration efficiency of 79.6 cm2/C, fast switching speed as short as 1.9 s for coloring and 1.6 s for bleaching, and excellent cycling stability over hundreds of cycles. Furthermore, ATA sandwich structured electrolyte makes full use of the excellent ionic conductivity and stability of Ta2O5, as well as enough lithium ions to meet the demand for fast color switching. Hence, ATA-based all-solid-state ECDs by continuous DC sputtering is expected to provide effective guidance for the mass production and practical application of the high-performance ECDs.

]]> <![CDATA[EDITORIAL: Eletrochromism Research in China]]> http://www.jim.org.cn/EN/10.15541/jim20200902 Electrochromism has been developed for more than 50 years since it was discovered in the 1960s. The optical properties, such as color, transmittance, reflectance and emissivity, of electrochromic materials can be changed reversibly under low applied voltages. Electrochromic materials have a wide range of regulatable spectrum, which can realize the broadband control from visible to mid far infrared. Electrochromic materials show a wide application prospect in the fields of intelligent window, display, anti-glare rearview mirror, intelligent thermal control and camouflage. In the past decade, electrochromism research has shown a trend of vigorous development, especially in China. Electrochromism is attracting researchers in the fields of nanomaterials, vacuum coating, lithium-ion batteries, supercapacitors, sensing and display to get involved in this interdisciplinary field, gradually becoming one of hot research topics.

In the last special issue: Electrochromic Materials and Devices (2021, 36(2)), we published 5 papers. 鈥淢ulti-functional Electrochromic Devices: Integration Strategies Based on Multiple and Single Devices鈥�, 鈥淓lectrochromic Devices Based on Tungsten Oxide and Nickel Oxide: a Review鈥�, 鈥淧rogress in Flexible Electrochromic Devices鈥�, 鈥淒ynamic Process of Ions Transport and Cyclic Stability of WO3 Electrochromic Film鈥�, and 鈥淗igh-conductivity Hydrophobic Fumed-SiO2 Composite Gel Electrolyte for High Performance Electrochromic Devices鈥�. In this special issue, experts working in the field of electrochromism from Harbin Institute of Technology, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Institute of Nanotechnology and Nano-Bionics, Chinese Academy of Sciences, Beihang University and University of Shanghai for Science and Technology contributed 5 papers. LI Yao鈥檚 group introduces the methods and principles of regulating the reflectance spectrum in the visible near infrared to mid far infrared bands and the latest research progress, and prospects the practical application of inorganic electrochromic materials in future. WANG Jinmin鈥檚 group introduces electrochromic materials and devices, preparation of molybdenum oxide films, modification of molybdenum oxide, and the research progress of molybdenum oxide based electrochromic devices. The paper also presents current existing problems and solutions of molybdenum oxide based electrochromic films and devices, and looks forward to their development prospects. DIAO Xungang鈥檚 group reports the preparation and electrochromic properties of lithium titanate thin films by spin coating method, and assembly of an all-solid-state inorganic electrochromic device. JIN Pingshi and CAO Xun鈥檚 group reports all-solid-state electrochromic devices based on LiAlOx/Ta2O5/LiAlOx (ATA) sandwich structured electrolyte fabricated by reactive DC magnetron sputtering technique. ZHAO Zhigang鈥檚 group reports the preparation of a multi-color tungsten oxide films with F-P cavity structure and their wide-spectrum electrochromic properties of visible and infrared spectral regions.

The special issue of Electrochromic Materials and Devices focuses on the latest research progress and future development trends in the field of electrochromic, and hopes that colleagues will benefit from it. It is expected that the electrochromism research in China will develop more rapidly in the future, gradually leading the new trend of international electrochromism research.

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