We’ve heard so very much hype about OLED tech that it’s slightly disappointing to see how few devices have an OLED screen so far. It’s because the manufacturing is tricky and expensive–but this is something DuPont thinks it’s cracked.
DuPont’s research team have been examining the manufacturing process that makes OLED screens possible, and have innovated a new system that’s both faster and more reliable. OLEDs, unlike LCD screens, are self-illuminating: Each pixel is a tiny light source, made up of a collection of minuscule glowing LEDs that have organic chemistry in their composition. This design is why they’re so very good at delivering dynamic high-contrast imagery since, without a backlight (such as LCD TVs need), the black areas of the picture are really black.
But OLED’s complex design does make them difficult to manufacture, though–effectively each complete OLED screen is a giant single-wafer computer chip, since the individual LED elements are deposited on the screen’s substrate in layers using a precise but slow “shadow-mask deposition” technique that gently lays down the 15 or so layers needed to create each LED and its driving electronic circuitry.
DuPont’s team has invented a way to speed up this system so that it’s more like a print-out production line. The trick is to vary the “inks” used in each layer of the OLEDs themselves, using active molecules that are soluble in the particular layer being printed, but not in the ones above and below. This stops the layers from “blending” into each other, which tends to significantly degrade the performance of the individual LEDs. As well as achieving all the complex chemistry in this, the new screens are made with a multi-nozzle printer that streams ink out continuously and scans over the displays at a high speed. The upshot is a system that can print out a 50-inch OLED TV in less than two minutes, meaning production costs scale to be comparable with LCDs and the screens have a lifespan of about 15 years.