- 3 Reasons Flexible Electronics Enable Smarter Displays
- For a decade or more, flexible electronics has been just over the horizon, beaconing from a future where all mobile computerized equipment could be rolled up like a bedroll for transportation. Despite these unfulfilled expectations, here are three ways that smarter displays are realizing the unfulfilled dreams of flexible electronics.Flash Gordon popularized the idea of flying cars more than 50 years ago, but still they are not here. Likewise, the era of mobile computers that you can roll up like a scroll could still be a dream 50 years hence.
Nevertheless, the technologies that caused all the speculation about flexible electronics are already revolutionizing the multi-billion-dollar display industry. Theoretically, flexible displays could be rolled up like a blueprint or pulled down like a window blind. The reality, however, is that flexible, printable, organic electronics are finding their best uses in cost-reducing three aspects of the manufacturing of electronic displays (albeit without making the entire display flexible).
Arizona State University's Flexible Display Center shows its active-matrix electrophoretic display based on E-Ink flexible touchscreen. Instead of using stiff glass for support, it uses a flexible DuPont Teijin Film.
According to Lux Research, which held a webinar on the subject Jan. 18 called “Sorting Hype From Reality in Printed, Organic, and Flexible Display Technologies,” there are three values that flexible electronics technologies are adding to modern displays.
1. Frontplane: The active display layers that provide pixel-level coloring have already been revolutionized by flexible display layers such as the electrophoretic technology used in Amazon's Kindle. Electrophoretic displays are built with flexible polymers instead of stiff silicon crystals, even though the rest of the display is stiff by virtue of the glass covering that protects it from spilled coffee.
For the future, active-layer frontplanes will be available using a wide variety of flexible electronic technologies, from organic light-emitting diodes (OLEDs) with super-wide-gamut color resolution to electro-wetting display technologies that have the ultra-low-power features to extend battery life in mobile devices, but can display fast-moving color video that a Kindle can't touch.
2. Backplanes: Thin-film transistors (TFTs) supply the signal to turn pixels on and off, necessitating a one-to-one relationship between pixels and TFTs (for instance, a five-megapixel display has five million TFTs). Today, silicon photo-masks are used to fabricate TFTs by laying down tiny patterns of photoresist on silicon sheets, which can then be etched into the shape of the desired thin-film transistors. However, techniques enabling printers to lay down the TFTs directly will soon lower the cost and manufacturing complexity of electronic displays.
3. Transparent Electrodes: The reason that displays appear to be transparent, despite the fact that every pixel is connected to a TFT that is printed on its backplane, is that the "wires" used to supply signals to the TFTs are transparent. Today, transparency is achieved by using indium tin oxide (ITO), which is becoming increasingly rare, thus driving up the manufacturing costs of displays. However, new formulations of flexible nanowires that can be printed at room temperature using silicon, silver, and pure carbon—graphene—promise to lower the cost of displays further by eliminating the need for costly ITO.