OLCD: A lower energy production process for displays
July 09, 2018
Most displays in our lives today are based on silicon thin-film transistors (TFTs), built onto glass substrates. Glass is used for several reasons: it is chemically inert, optically clear and extremely flat, but most importantly it can withstand the high temperatures (around 300°C or more) needed to build the silicon transistors.
Larger display factories mean more resource consumption
As demand for displays continues to grow, so the size and scale of new display factories increases, partly for economies of scale, and partly because consumers want bigger screens – for example the average new TV size will increase by around one inch per year over the next five years. As a result, the latest generation of TV factories (so called “Gen 10.5”), are huge. A typical Gen 10.5 factory will be able to produce 10 million square meters of TV screen per year, will employ around 6,500 people and have a clean room of over half a million square meters. The power requirements for such a facility is equivalent to a medium sized power station, requiring up to several hundred megawatts of on-site capacity.
The reason for such high power requirements is that some of the process steps employed in manufacturing silicon TFTs are particularly energy-intensive: annealing, sputtering, reactive ion etching (RIE), ion implantation and chemical vapour deposition (CVD) all use a significant amount of energy per display, and we are producing ever more displays. By 2021 our planet will be producing close to a quarter of a billion square meters of display per year. Reducing the energy consumption per display is therefore of strong environmental importance as well as economic.
OLCD – a lower-energy production process
Organic transistors, like those used in FlexEnable’s Organic LCD (LCD) technology, bring many benefits to products, in terms of thinness, lightness, flexibility, whilst also having the lowest production costs of any flexible display. These attributes are driven by the unprecedented low temperature process that’s possible with solution-processed organic thin-film transistors (OTFTs), meaning that production can be carried out at maximum 100°C, rather than 300-400°C. As well as the much lower processing temperature, OTFT also does not require energy-intensive processes like CVD, because the CVD is replaced with simple solution-coating processes. Some estimates have been published that moving from PolySi TFTs to evaporated OTFTs reduces process energy by a factor of 10. Further reductions are expected when moving to solution-processed OTFT.
More generally, moving to low-temperature plastic display production has benefits right along the supply chain: new product designs and applications for OEMs, increased areal sales for display makers and volumes for materials suppliers, and lower energy production manufacturing for the planet.
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