What Is Electrochromic Film?

Electrochromic (EC) film is a fairly commonly used material and is similar in technology to electrochromic glass.

Electrochromicology is a science that involves coloration of materials such opaque or transparent film material to affect change.

It’s interesting to note that film material was originally composed of vegetable, mineral and animal ingredients. This is a clue to how electrochromic films are processed.

However when film was originally invented, it was made from cellulose nitrate. Today film is made from either a cellulose acetate or polyester base and has a coating of “light sensitive” minerals, chiefly silver salts.

The Link Between EC Film and EC Glass

Electrochromic film is intended to be heat and light-sensitive so that it is more useful to a wider range of products as an EC device. There is a distinct link between electrochromic film and electrochromic glass, both are an electrochromic material but the film thickness and flexibility is much different than that of EC glass.

The process is relatively simple to understand. To set up a distributable electric field, voltage is applied between transparent electrical conductors in the electrochromic layer- mostly using an electrolyte or lithium ions to change the transmittance spectra of the electrochromic films.

Imagine the distributable electric field as an orbit with invisible positive and negative lines that can be equal. So, you insert an electrical plug into an outlet and it is connected to the volts that activate an electrical charge.

This is similar to what electrochromic film does to glass materials. Light changes according to volts to make electrochromic film sensitive to light, just like in an electrochromic window. In an electrochromic device, electrical volts with lithium ions and electrons create a field of sensitivity that disperses light in a layer.

The History of Electrochromic Film

The early history of electrochromic film begins with the discovery of electrochromism when a dye maker, Johann Jacob Diesbach, in 1703 discovered in the process of making paints for artists, he accidentally mixed an ingredient in cochineal, used to make red dyes, with potash, which is an alkali and saw that it changed to blue. It was known as Prussian blue. This was electrochemical oxidation, a chemical and optical property that allows for the fast switching speed of the colored state of a material.

That mishap created the color that changed the world and for many artists, like Vincent Van Gogh whose painting, “Starry Night” typifies the use of this extraordinary color find.

From that point on combining tungsten oxide and an alkali led to the ability to color change light on paper, glass and other materials through applied voltage in a substrate. Thus, through the use of ions and electrical volts the EC process was established.

Enter Tungsten Oxide Film

When experiments were carried out on electrical properties of tungsten electrodes, the result was the forming of an oxide film. It’s easy to see why tungsten oxide film plays a role in electrochromic performance in smart glass and EC film.

As with LCD technology, EC technology requires liquid crystals and an ion storage layer, and are also a significant part of the optical property of the electrochromic layer of thin film.

Smart glass resembles a multi layer sandwich. The outer layers can be glass, paper or metal while the inner layers are EC film. Glass electrodes play an important role in chemical analyses and chemical studies in labs and research and development of new technology such as EC film.

A glass electrode is an ion selective sensoring component that detects changes in light or heat. Through the electrode transmission process, only ions are introduced into a liquid crystal structure of a crystalline member or film.

The Scientific Process

For most of us there are two ways to view EC film: First as a highly scientific process and secondly, as a more generic, practicable process that is as useful as it is convenient in generic applications.

A scientific process is not so very different than a baking recipe. It has ingredients as components intended to produce a desired result and a protocol (directions) that confirm analytical findings. Thus the EC scientific film process requires three main ingredients that include:

. Chemicals such as tungsten oxide

. Electrical stimulants such as electrodes and ions

. A reactive substance or material such as glass, paper, polymer or metal

Most people are more familiar with the generic process of EC film because of its usefulness and convenience. Instead of fabric shades or curtains on windows that darken a room, windows with EC film do it automatically by sensing changes to varying degrees of light in the entire room. Through transmittance of core electrochromic properties to glass material, it is possible to maintain and regulate sunlight.

Uses of EC Film

Windows and doors are only one use of EC film. Existing windows and doors are replaced with smart glass and in new homes and buildings these are pre-installed with EC film on glass windows and doors at time of manufacture and before these structures are sold.

However, there is the option of stick on EC film that adds a thin film to existing the surfaces of windows and doors. In addition to glass material that regulates light, EC film also helps retain heat. This is a valuable energy saving feature that reduces energy costs.

One necessity for high heat control is graphite. Graphite is used to make a graphite electrode as a conductor of electricity when free electrons such as those found in an electrochromic device, are present. A graphite electrode is considered to be a semi-metal by the solar energy industry.

In the solar energy industry, solar cells may be made of graphite and titanium oxide. Using the multiple layer sandwich example, a solar panel has an aluminum frame beneath which is a layer of tempered glass that protect solar cells. encapsulant material and a junction box.

When solar panels are treated with EC film as a transparent conductor of renewable energy, the sun does the job of emitting electromagnetic radiation also referred to as solar radiation.

Through the use of electrochromic technology, solar radiation is captured by tempered glass coated with EC film. Each nanoparticle in solar cells store solar radiation as detected and collected by the EC film on the glass layer of the solar panel.

In this process, EC film serves as a magnetic semiconductor of heat and light.

EC Film of the Future

When it comes to electrochromic film, it’s easy to imagine how this technology will continue to evolve long into the future. Once you envision the idea of adding film that senses changes to sunlight and heat, the possibilities for future use are endless. These possibilities include:

. Time and temperature applications

. EC pixels for digitizing

. Multispectral energy modulation

. Smart heating thermostats

. Cooking and baking equipment

. Rear view mirrors in vehicles with light sensors

. Heavy duty industrial equipment

. Spectroscopy

. Engineering equipment such as probes and micromanometers

. Virtual reality equipment

. Medical equipment

. Reflective overlays for sensitive sheeting for municipal safety devices

. Advanced lighting patterns for traffic

And That’s That

Though electrochromic technology may seem complex to the average individual when all of the components are taken into consideration the realistic view is quite simple. A technology that changes every day life is always readily accepted and soon becomes a utilitarian expectation.

If we expect our sunglasses to adapt to changes to make our vision more precise and less compromised, why not expect the same of solar panels and the household and business equipment we rely on to make work less difficult?

Advanced applications of EC film will inevitably become more available for home and business use. In fact, in years to come, it may be possible that curtains will be obsolete when heat and light-absorbing film is applied to windows. Insulation materials would also be a thing of the past. If you can dream it, it can be done.

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