What is ITO Glass Coating and How is it Used?
Indium tin oxide (ITO) is a hugely useful transparent conducting oxide coating that can be applied as a thin film onto glass surfaces. This advanced material has opened up various high-tech applications thanks to its unique combination of electrical conductivity and optical transparency.
What is ITO?
ITO is composed of 90% indium (III) oxide (In2O3), and 10% tin (IV) oxide (SnO2). Although indium tin oxide sounds metallic, it is actually colourless and transparent when applied as a thin coating onto glass or clear plastic surfaces. The tin oxide dopant gives the material its electrical conductivity, while the indium oxide provides transparency and bonding properties.
The thickness of ITO coatings on glass can range from around 100-500 nanometres. At these nano-scale dimensions, visible light can easily pass through, allowing a sheet resistance of less than 10 ohms per square. This makes ITO an ideal transparent electrode for use in flat panel displays, touch screens, LEDs, solar photovoltaics, and other electronics applications. ITO on glass can be found via manufacturers like Itotek Ltd.
Touchscreen Displays
One of the most widespread uses of ITO glass coatings is in touch-sensitive display screens and interfaces. From smartphones and tablets, to self-service kiosks and interactive whiteboards, ITO allows the display overlay to act as a large conductive sheet sensitive to human touch.
When a finger touches the screen, the ITO coating detects the location thanks to changes in the electrical charge across the display area. It then communicates this to the device’s software, telling it exactly where the user has touched or swiped on the screen. ITO touchscreens are also compatible with stylus pens for precision input.
Smart Windows & Glass
Another growing application is ‘smart’ windows and glass that can change transparency on demand. Known as ‘switchable glazing’, these windows have an ITO coating bonded to the inside of two overlaid glass panes encompassing a liquid crystal or gel electrolyte layer.
When a small electric charge is applied, the electrolyte shifts orientation, blocking light transmission and turning the entire glass sheet opaque or frosted. When switched off, the glass returns to a fully transparent state. This allows degrees of privacy, shading, or even projected imagery where desired. ITO coatings are integral in allowing the glass to switch between clear and opaque states electronically.
Solar Cells
Indium tin oxide also plays an important role as a component within thin-film solar photovoltaic cells. The thinness and transparency of ITO coatings make them well-suited as front-side electrodes on solar panels. The ITO layer usually tops the light-absorbing semiconductor material, enabling current to flow to the cell’s edges whilst letting maximal sunlight through from above.
From intuitive touchscreen devices to smart glass facades and windows that adapt to ambient conditions – indium tin oxide is driving forward human-machine interfaces and buildings that intelligently respond to their environment. This advanced transparent conducting oxide that ‘disappears’ before our eyes is truly an amazing feat of science and looks set to enable further technologies we’re yet to imagine.
