The Orientation: Organic light-emitting diodes

Being green and working in the tech world often times don’t mix. The manufacturers of everything that gets me giddy takes a huge dump on Mother Earth in the process and that stinks. Green Peace keeps tabs on companies and lets us know who piddles in the pool and who takes a hungover-all night bender-Hot Pocket eating-dump. But we’re a long ways away before each and every company on the planet adheres to the rules and realizes what they’re doing to the environment.

Ok, I’ll get off my soapbox now and talk about OLED.

Organic light-emitting diodes, or OLEDs as we’ve become familiar with them, is the hot new buzz in displays. Sony has a tiny 11-inch OLED HDTV that costs a whopping $2,500. It also helps that it’s only 3mm thin. OLEDs are typically brighter, crisper and use far less electricity than normal LEDs or LCDs. That’s fine and dandy, but where did all of this begin and is it really that new? Yes and no. OLED technology has been around since the 80s thanks to Eastman Kodak, but it hasn’t hit the consumer market until recently.

oled cell

So what makes an OLED an OLED? Well, think of it like a sandwich. The top layer consists of a cathode followed by an emissive layer then a conductive layer, an anode and then a substrate. Both the emissive and conductive layers are organic in some respect. Each film consists of a hole-injection layer, hole-transparent layer, and an emissive layer that is then followed by an electron-transport layer. When a bit of juice is applied to the OLED, the positive and negative charges come together in the emissive layer and create light. To further elaborate on this I’ll try and break it down as best I can from the brain cells that are still around from college and retained some of this knowledge. The flow of electricity goes from the cathode to the anode via the layers in between. The positive electrons are pulled from the cathode through the emissive layer, which is then extracted by the anode through the conductive layer. When this happens all the positive balls of energy cluster together and bam. We now have light. Of course, it’s entirely way more detailed than that, but I think you get the drift.

oled process 1

What are the advantages of OLED? They’re a heck of a lot brighter than LEDs. They’re also lighter and more flexible than LCDs and LEDs. They don’t require any backlighting like LCDs. They can be made as large or as small as someone wants since substrates are easy to come by and these tend to be plastic and/or flexible, opening the door to a whole world of possibilities. The viewing angle is much better than on LCDs and the response time is way faster as well.

The advantages certainly outnumber the disadvantages, but the disadvantages are a huge deal as to why OLEDs aren’t more readily available in devices today. They’re crazy expensive to produce. An 11-inch TV that costs $2,500?! Exactly. That’s a red flag. Lifetime on the OLEDs isn’t that great, either. It’ll last roughly 5 years if it’s left on for 8 hours a day. But it’s a work in progress. I hate to say it, but my favorite element is a real killer here. Any amount of water will destroy or severely damage the organic materials involved rendering your investment worthless.

In the coming years, we’ll see all sorts of variations of OLEDs in various devices. It seems like a lot of mobile phone screens are getting the AMOLED treatment and the main difference is that an AMOLED has a layer of TFT underneath the Anode that forms a matrix. Because of this combination, certain pixels get turned on while others don’t. The possibilities here look to be endless. Anything with a screen can be replaced with OLEDs. That reduces the amount of power being used and gives us better picture quality. Don’t you just love the future of technology?

Images from How Stuff Works.