Homebrew OLED

The goals of this project were pretty simple in theory: make an Organic Light-Emitting Diode (OLED) outside of a corporate research environment. Preferably, a transparent one.

For simplicity’s sake the idea of a real pixellated screen, even monochrome, was abandoned in favor of a simpler light idea- to have a single OLED printed in a pre-defined shape that could be turned on or off. Color didn’t matter, whatever material would be cheapest would be used. We’re working on a budget here, after all.

I decided on Indium-Tin Oxide (ITO) for my cathode and anode, and Alq3 and some other carrier/assisting materials in the middle. These layers would be deposited onto a glass substrate, then faced with another sheet of glass and sealed airtight to keep oxygen radicals from breaking down the Alq3 over time (a common problem with this material, but it was the cheapest light emitter available). Looking at it from a side view, the major chemicals/materials would look like this:

Glass
ITO
Alq3
ITO
Glass

By applying electricity through positive electrodes across the top plane and negative electrodes across the bottom, the conductive ITO “bread” would draw current through the Alq3 “meat” and energize its molecules, mixing electrons and electron holes (spaces for electrons at lower energy levels). When an electron meets a hole, it drops into that lower energy level, releasing the excess energy as light.

Unfortunately, Indium is one of the rarer elements, and ITO is accordingly pretty expensive. But it’s one of the few materials that’s transparent in thin films, and so necessary to build a completely transparent screen. Or any screen, since the light comes from the Alq3 in the middle, so at least one side has to be transparent.

But unfortunately, due to the necessity of depositing all these chemicals in extremely thin films, I would likely require several thousands of dollars worth of lab equipment to manufacture my design. I thought I had one of those labs in RIT’s Microfabrication lab, but alas, they can only really deposit on silicon wafers- not exactly what I was looking for, as silicon is neither Organic nor transparent. What I really need is a spin coater that can handle glass substrates.

This project may be re-imagined if I can find more papers about OLED printing, the idea that an inkjet printer can be modified to print OLED chemicals onto substrates. The chemicals are still expensive, but a lot more reasonable than buying a spin coater.

As OLEDs become more and more widespread, more and more papers are being published from which us homebrew hopefuls can gain more information about manufacturing processes. This design is based mostly on my own research into the field via papers and books I’ve read and conferences I’ve managed to get into. (One was actually a display conference for Taiwanese businessmen, but technically open to all RIT students since it was held at RIT. I was the only student in attendance, in my jeans and t-shirt, and was completely surrounded by old Asian men in suits. It was awkward, but I learned a lot.) But as more of these papers become available, and as more information about real corporate research is released, we have a better and better chance of being able to take back research from corporations and return it to academia and hobbyists.