Tungsten Oxide Electrochromic Thin Film-Boeing 787 Dream Window

The dream window of Boeing 787 owns the ability to dim or brighten without the window shades. The effect is very similar to the tungsten oxide electrochromic thin film.

The Boeing 787 Dreamliner is an American long-haul, mid-size widebody, twin-engine jet airliner made by Boeing Commercial Airplanes. Its variants seat 242 to 335 passengers in typical three-class seating configurations. It is the first airliner with an airframe constructed primarily of composite materials. The 787 was designed to be 20% more fuel-efficient than the Boeing 767, which it was intended to replace. The 787 Dreamliner’s distinguishing features include mostly electrical flight systems, raked wingtips, and noise-reducing chevrons on its engine nacelles.

The windows are a dreamy 19 inches tall and 65% larger than the standard airplane windows so you'll get to see a lot more of your surroundings.

Although Boeing 787 windows do not have shades, the electro-chromatic dimmable windows give cabin crews the ability to dim or brighten an entire cabin at the press of a single button. Of course, the captain can also dim directly in the cockpit when the night falls. Besides, the discoloring of electronic window is gradual, so you don’t have to worry that your eyes will be uncomfortable. What’s more, the window will be completely clear when blackout occurs. Some readers may wonder whether it is possible to implement this dream window at home easily or not. It seems a mission impossible. In fact, we only need a cool technology which can make you enjoy dream window at home--- the tungsten oxide electrochromic thin film.

Every time we try something new, we will start from its concept and principle. Let’s learn about the concept of electrochromism. Electrochromism refers to a phenomenon in which the optical properties (reflectance, transmittance, absorptivity, etc.) of a material undergo a stable and reversible color change under the influence of an applied electric field which can be observed from the reversible change of color and transparency. So, what is the principle of electrochromism? The principle is that the use of electric energy can change the color of a conductive medium sandwiched between two thin pieces of glass, such as gel. Electric current flows through the transparent conductive layer on the outer glass, and causes a chemical reaction of the electrochromic medium which leads to a change of the transparency of the medium. To be more specific, we can learn the principle of tungsten oxide electrochromism. The medium is tungsten trioxide film. As the small voltage is applied to the film, it darkens. When blackout occurs, it can return to a transparent state. The voltage can be precisely under control. The required transparency can be obtained by increasing or decreasing the voltage.

As for the practical application, this glass can be regarded as a type of smart glass. Under the influence of electric field, the glass is characterized by the adjustability towards transparency. It can selectively absorb or reflect external heat radiation and internal heat diffusion, thereby reducing the amount of energy that must be consumed by residential and office buildings. In a word, it is beneficial for energy saving and emission reduction. Meanwhile, this smart glass can also improve the natural light level and prevent people from being peeped. The press of a single button can solve many problems!

Tungsten oxide owns the property of electrochromism, that is, it is a kind of electrochromic material. The devices which are made by electrochromic materials are called electrochromic devices. There are some applications of these devices, such as EC display and EC anti-glare rearview mirror. The electrochromic materials have the property of bistability. Therefore, the EC display does not need the backlight. As long as the display content does not change when it displays a static image, the energy won’t be consumed. At present, most anti-glare rearview mirrors are made by liquid crystal so that they can only switch between light and darkness, which gives your eyes an uncomfortable feeling. When summer sunlight is strong, the sunlight will do harm to people’s eyes and lead to car accident. However, EC anti-glare rearview mirrors can adjust the reflectivity automatically according to the outside condition which makes people’s eyes comfortable. 

Finally, let’s take a look at the material requirements for tungsten oxide electrochromic thin film glass. In practical applications, especially in the preparation of electrochromic devices, electrochromic materials generally meet the following requirements: good electrochemical redox reversibility, fast color change response, reversible change of color, high sensitivity of color change, long cycle life, a certain storage memory function and stable chemical properties.

Electrochromic materials are widely applied to information, electronics, energy, construction, defense and so on. As one of the most promising smart materials at present, electrochromic materials have been extensively studied, such as the study of inorganic metal oxides. Nowadays, many devices made by WO3 electrochromic materials have been put on the market. In the future, driven by the implementation of the national environmental protection policy and the urgent need for energy saving and emission reduction, the installation of the “dream window” at home is possible to be realized.

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