Every transparent OLED demo I’ve seen so far looks amazing for about ten seconds, right before I notice how dim or smudgy it actually looks. A big part of the problem is the role that electrodes play in the design.
A transparent display requires a see-through electrode that sits on top of incredibly delicate organic light-emitting layers. However, most of the usual options either conduct electricity poorly or risk damaging those layers during manufacturing.
So how exactly does this new electrode get made?
A team at Seoul National University, led by professor Yongtaek Hong, just found a way around that, and a clever one no less.
Instead of using harsh chemicals or etching to add a metal layer onto a finished OLED, which can damage the organic materials underneath, the team first stamps down a pattern of a special coating.
Instead of etching a metal layer onto a finished OLED, which can damage the organic materials underneath, the team first stamps down a pattern of a special coating (an elastomer). When metal vapor is added next, it sticks everywhere except on top of that coating, which repels it.
Without any rinsing or lift-off, we get a self-aligned metal mesh electrode that is 93.6% to 99% transparent with sheet resistance as low as 1.1 Ohm per square, which is extremely low for a transparent electrode, results in better electrical conductivity, according to the study published in Materials Horizons (via EurekAlert).
Why should you care about an electrode, of all things?
Because this lesser-known component is what has been holding back transparent displays. The team’s electrode scored a figure of merit above 10,000, which they call one of the best results ever reported for something as thin.
Hong says the technique could become a go-to method for transparent and flexible displays, AR devices, car screens, smart windows, and even under-display facial recognition panels.
This doesn’t mean that a transparent iPhone or Samsung Galaxy S-series ships next year. But fixing the boring manufacturing problem is exactly how these screens go from demos to something you would actually want to use.
