Flat panel displays

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Flat panel displays can be grouped into several different categories based on technology and the materials contained inside. The oldest one is LCD displays, then came plasma displays for larger TV:s and lately OLED displays have arrived on the market.

The common component in all these technologies is the drive electronics, cables, a steel / aluminum frame and plastic casing. These components can be refined or recycled as any other electronic scrap.

There are only small amount of precious metals in the displays, silver in plasma displays and small amounts of silver in some OLED:s. There can also be integrated circuits and connectors at the edge of the display that could contain a bit of gold or silver. References talks about rhodium being used in the manufacturing of glass for LCD and plasma screens (49000 oz during 2006) and also ruthenium, but if it's used in the glass furnace or deposited on the screen is not clear.

There is new development (2013) in the area of transparent conductors and an alternative that can replace Indium Tin Oxide (ITO) in flat panels is Silver Nano Wires (SNW) and that would make ordinary LCD:s a source of silver too.

Contents

LCD

In principle the display is made up of a back lighter, a polarizer (plastic film) and two sheets of glass with liquid crystals in between. To control the light passing through the display the conductors have to be transparent. A mixture of indium and tin oxides are used and sits on the inside of the glass sheets. The amount of indium used in a screen is tiny, about 0.01% of the weight of the glass. (0.1g / kg) The liquid crystal is a mixture of 10 to 25 different compounds and are highly toxic to the environment. It can be dissolved in a solution of 17% (vol%) isopropyl alcohol assisted by ultrasonic.

Plasma

In a plasma screen (mostly used in TV sets) the light is created in small gas discharges inside the screen. The conductors in this case is often made up from silver and reports are talking of 0.6 g/kg up to 30 g/screen but often "a lot less".

OLED

OLED stands for Organic Light Emitting Diode and is a way to build a screen from a matrix of LED dots made by carbon based components. The main advantage over older technology is power savings as there is no backlighter, it is lighter since there is no glass screens and it is flexible and can be made into curved shapes. Electrical contacts in OLED could be made from silver or indium tin oxide.

References

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