In the future we should hope for all of our displays to be OLED; it’s thin, light, deep with colour, and energy efficient to boot. It’s also incredibly expensive. That could soon change though thanks to a jumped-up inkjet printer.
A company called Kateeva has been developing a new technique, which it’s now made available to display makers, which uses technology similar to that in a domestic printer to create displays. A moveable platform precisely positions glass or plastic panels beneath printheads, each of which contains hundreds of nozzles. Each nozzle can deposit picoliter droplets — that’s a trillionth of a litre — in exact locations to build up the pixels of a display.
Usually OLEDs are made in a vacuum chamber, where thin films of organic materials are deposited by condensing vapours onto the panel, using a fine metal stencil — called a shadow mask — to make sure it ends up in the right place. But that technique is often wasteful: the vapours condense onto the entire surface, stencil and all, so it uses more material, and the act of removing the stencil can easily damage the displays too. That means a lot are written off, which jacks prices up.
The inkjet method promises to solve both problems, although until now it’s been far from a commercial possibility because the deposited materials aged badly. Now, however, as MIT nanotechnologist Vladimir Bulović explains, “the latest material sets are actually extremely stable” when printed.
The only possible downside to the process, then, is that it’s “dirty”, at least in the sense that no mask is used, so it’s possible for material to fall where it’s not wanted. Kateeva insists that careful design mitigates this potential problem; in fact, it says it’s reduced particle contamination by as much as 10 times compared to conventional processes. All of which suggests that ink jets could, before too long, be used to print your TV, as well as your documents. [Technology Review]