The AV industry is filled with acronyms: LED, LCD, ULED, OLED, HDR, DLP, and of course AV, just to name a few. All these letters can get confusing if you aren’t immersed in the terminology on a day to day basis and one of the most common mix ups occurs with the phrases LED and OLED. These acronyms are obviously quite similar but don’t let that trick you into thinking the technologies themselves are the same. Let’s clear up some of this confusion by asking and answering some questions about these evolving display types.
What does LED stand for?
LED stands for Light-Emitting Diode.
What does OLED stand for?
OLED stands for Organic Light-Emitting Diode, and while OLED diodes are technically “diodes that emit light,” they are not quite the same as traditional light-emitting diodes like those made by NanoLumens.
What’s different about OLED then?
Both LED and OLED diodes emit light through electroluminescence, the production of light in response to the running of an electrical current. Electroluminescence is what happens when negatively charged free electrons, excited by an electrical current, combine with positively charged “electron holes” within a semiconductor. Because the electron holes have a lower energy level than the electrons themselves, the electrons must release energy in order to combine. (You can read about that process here.)
While the traditional LEDs used by NanoLumens create light when a current is run through an inorganic semiconductor, an OLED creates light when this current is run through a film of organic compound functioning as a semiconductor.
What are these organic compounds?
The organic compound within an OLED device varies but the very first OLED devices employed small organic molecules deposited onto substrates using a costly and inefficient process called vacuum deposition. Many OLED products are still made using this process which explains their high price point relative to other technologies. Some recent versions of OLED devices now use large polymer molecules like polyaniline for their conducting layer and polyfluorene for their emissive layer. These organic polymers are more easily produced and deposited onto substrates.
Is using an organic compound as a semiconductor better?
Using an organic compound as a semiconductor, as OLEDs do, is not inherently better or worse than using an inorganic semiconductor. The greatest practical difference derived from using organic compounds is that you’re able to mount the diodes onto a wider variety of substrates. While traditional LEDs perform best when using direct band gap materials, OLEDs can function with indirect band gap materials and thus can be mounted onto substances like silicon.
What are the advantages OLED provides?
Because OLEDs can use plastic substrates, they can create display surfaces that flex, roll, bend, and contort in ways traditional LED displays cannot. OLEDs are lighter than LEDs and a bit brighter as well.
What’s the catch?
Well, while OLEDs certainly seem like a flashier display solution, they are not nearly as durable as a traditional LED and are far more expensive to boot. While the diodes NanoLumens uses have lifespans of 100,000 hours to half brightness, blue OLEDs have typically been known to last only 14,000 hours (though companies creating OLED products will claim otherwise). In any case, that these blue OLEDs degrade faster than other color OLEDs can eventually corrupt the color balance of a display. An additional complication is that OLEDs can decay even when not in use due to oxygen and moisture ingress. OLEDs are also more sensitive to temperature.
What’s the conclusion then?
While exciting in its application in smart phones, televisions, and (eventually) wearables, OLED technologies are not really viable in the large-format space right now so commercial AV consumers need not dedicate much focus to it. Ultimately, the only reason we’re talking about it is because it includes our three favorite letters: LED! If you have any further questions about LEDs and related AV technologies, we encourage you to register for our upcoming webinar on November 14th where we’ll be hosting a Q&A with our Vice President of Systems Engineering!