UDC is one of a handful of companies pioneering OLED development and manufacturing techniques for the big boys such as Samsung, Sony, LG and of course, the US Department of Defense. No one's written about how they make these displays, panels that'll make up our next generation of super-slim HDTVs, until now. This week, Benny and I visited Universal Display Corporation's headquarters in Princeton, NJ for an exclusive tour of the factory, where we witnessed just how they make 'em. We gowned up, donned stylish hairnets and observed OLED panel fabrication up close, a process that involves expensive super-heated dope and something called a shadow mask. (Sounds like fairly nice evening in Vegas, doesn't it?)
OLEDs (organic light-emitting diodes) differ from LCDs in that they don't need a backlight of any kind, because each pixel is made of a phosphorescent particle that lights up on its own when excited. The trick is getting the particles onto the glass, plastic or metallic screen - the substrate, they call it - in an orderly fashion. There are a few techniques, but here's the basic process:
1. The phosphorescent coloured particles, or "dope," are prepared. The three colours, red, green and blue, are actually made from powders that are red, yellow and orange. To this day no one is certain why. The powder is carried in vials to the fabrication room.
2. Meanwhile, in a Class 100 clean room (shown in video and gallery under UV protective yellow-tinted glass), the substrate is prepared to be fused with the particles. I think I saw a salad bar in the back, but our guide, Janice Mahon, VP of Technology Commercialisation, only laughed knowingly. Intel has Class 10 clean rooms, btw, but Jesus says his mum's house is even cleaner than that.
3. Here's where the magic happens: dope meets substrate in a sticky act of love. In the big business of OLEDs these days there are four ways to make this happen:
• Vacuum Thermal Evaporation - This is UDC's tried and true technique, a hot and steamy method involving super-heated dope that evaporates up into a grid, known as the shadow mask, that is placed over the substrate. First the red particles are evaporated, then the grid is shifted ever so slightly, then green is evaporated, then a final shift for blue. In the end, the panel has RGB pixels evenly distributed across the whole thing. Since you have to hang the shadow mask up under the substrate, there's a chance it could sag on larger screens, so VTE is aimed at smaller screens.
• Organic Vapor Phase Deposition - This is where the vapour is heated up then streamed into a system of "showerheads" that deposit the particles on a cooled substrate.
• Ink-Jet Printing - If the dope can be mixed into liquid form, it can run through technology similar to the stuff inside your printer. Precise depositing of dots on a substrate is easy, but the challenges are turning the dope into a liquid and then depositing the right amount in little wells on the substrate where they can dry.
• Organic Vapor Jet Printing - It's what it sounds like, a printing technique that lets you shoot particles through a printhead and straight onto the substrate. The benefit of this is that you don't have to turn the stuff into a liquid first, and you don't have to worry about getting the particles to dry later. But it's still really really hard.Glass is the easiest thing to use to make OLEDs, because it is rigid and because it is not porous: moisture and oxygen can't get in and ruin the little glowing organic molecules. Plastic is the worst, because it is easily penetrated. Metal foil is a middle ground, because the metal side keeps the molecules secure, but the glowing side still needs a special coating, and won't last as long as a glass OLED.
Like phosphors in a plasma TV, OLED materials fade over their lifetime, even when tightly sealed. At this point, red and green last hundreds of thousands of hours, so they could easily last as long as other technologies. But blue is still an issue. In any situation, it's going to be the first to go, though some OLED panels are now being rated in the 50,000-hour range.
Next up for UDC is a working flexible screen on metal, hopefully sooner than later. [UDC]
–Video was shot and edited by the multitalented Benny Goldman; I took the photos.