All modern televisions use one of two basic display technologies: LCD and OLED. The vast majority are LCD, and only some more recent TVs from LG and Sony are OLED. While LCD may be the norm, OLED TVs offer better picture quality overall, though at a higher price.
You may have heard OLED discussed when it comes to mobile phone displays. The top-of-the-line models from Apple, Samsung, Google and others, use OLED screens. This is similar, though not exactly the same, as the OLED tech found in TVs.
What makes OLED different from the LCDs found in most homes? How do they create better-looking images? Why are they so expensive? Read on.
OLED stands for organic light-emitting diode. Each pixel in an OLED display is made of a material that glows when you jab it with electricity. Kind of like the heating elements in a toaster, but with less heat and better resolution. This effect is called electroluminescence, which is one of those delightful words that is big, but actually makes sense: "electro" for electricity, "lumin" for light and "escence" for, well, basically "essence."
What's the "organic" part? The specific electroluminescent materials used in OLED displays are organic compounds, which means they contain carbon plus some other ingredients. Each color requires a different organic compound (though these aren't necessarily the colors you see on the TV -- more on that later).
What this means is that each tiny OLED pixel in the screen creates light depending on how much electric current you send it. Lots of current, lots of light. No current, no light. And that's one key to OLED's excellent picture quality.
OLED TV marketing often claims "infinite" contrast ratio (expressed as the brightest white divided by the darkest black) is technically infinite. And contrast ratio is arguably the most important aspect of picture quality., and while that might sound like , it's one of the extremely rare instances where such claims are actually true. Since OLED can produce a perfect black, emitting no light whatsoever, its
OLED TV highlights:
- Extremely dark blacks
- No "blooming" around bright objects on a dark background
- Best contrast ratio of any current display type
- Not as bright as most LCDs
- Currently only made by LG Display, though sold by LG and Sony (and other brands outside the US).
OLED vs. LCD
OLED is the only technology capable of absolute blacks and extremely bright whites on a per-pixel basis. LCD definitely can't do that, and even the vaunted, beloved,plasma couldn't do absolute blacks.
Why can't LCD do that? The liquid crystal that makes an LCD an LCD only blocks the light created by its backlight. It's like putting sunglasses in front of a candle. Even the best LCDs can't completely block all the light, so in order to get those inky movie-theater-like blacks, you have to turn the backlight down (the "candle" in this analogy).
In the most LCDs, the entire backlight works as one, dimming the entire screen (if that).LED LCDs are far better, but still only dim and brighten relatively large "zones" of the screen independently. With OLED TVs, the "dimming" operates on a per-pixel basis. So while the best local dimming LED LCDs may have a few dozen, a few hundred or dimming zones on the screen, a 4K OLED TV has more than 8 million -- one for each pixel. No LCD has as much control over each pixel's brightness as an OLED TV.
OLED doesn't have the extreme light output of the best current-generation LCD TVs, though. They're still very bright, and have better blacks for a better contrast ratio, but in a well lit room, or in direct sunlight, you'll be able to see an LCD better. Because of that better contrast ratio, in most other situations, or in a room with curtains, TV shows and movies -- everything from standard-def to high-def to 4K with-- all really pop.
Yellow plus blue makes green (and red and cyan and magenta)
Currently, all OLED TVs are made by LG, and how they've made them is rather unusual. All TVs, to create the images you watch, (well, not quite all colors, but most). To create the colored light, LCDs use RGB color filters, while plasmas used RGB phosphors and Samsung's short-lived OLED TV (and all their OLED-screened phones) use red, green and blue OLED elements.
LG's OLED only use two colors: a sandwich of blue and yellow OLED materials. Then, using color filters, the yellow and blue light is filtered to create red, green and blue. To add a bit more brightness, there's also a clear "white" element, too. It's a lot easier if I show you:
Though this seems odd and convoluted, it obviously works since LG is the only company that has successfully marketed large-screen OLED TVs in any numbers. This is because it's more cost-effective to make ("more" being the key word there).
The apparent downsides, such as light output and color accuracy, don't seem to be issues. Sure, they're not as bright as the brightest LCDs, but they are still very bright, and the current models have the same color saturation as the best LCDs.
Speaking of apparent downsides, here's another: burn-in. Or at least, the potential of burn-in. Burn-in is when an area of the screen can't produce the same amount of light as the rest. It's essentially more worn out than the rest. That section might look like it has a bit of a shadow, or in extreme cases, you can make out the shape of what burned in. For example, a shadowy after-image of a news station's channel logo might be visible when you change the channel.
OLED TVs are susceptible to burn-in, but in all but the most extreme cases what you'd see is more accurately described as "image retention." Image retention goes away after watching something else for a few minutes. Burn-in is permanent, and would only happen if, say, you only ever watch one channel for 8 hours a day every day. As long as you use your TV to watch a variety of content (i.e., more than one channel), you should be fine.
We don't think burn-in will be an issue for most people, which is why we still recommend OLED TVs for people looking for the best image quality. If you're curious about burn-in and image retention, check out.
Another common question I get about OLED TVs is about how long they'll last. The blue OLED material was always shorter-lived than other "flavors" of OLED. But wait! I hear you exclaim. Wouldn't that mean the LG's whole TV will die out at the faster blue rate, since every pixel incorporates blue? Apparently pairing the blue OLED with yellow, as LG did, provides longevity benefits.
According to LG's spokesman: "We have secured a lifespan for OLED TVs of more than 50,000 hours, which is generally longer than conventional TVs." So if you watch six hours of TV a day, that's over 22 years of use.
At least, that's how long they expect the panel to last. On most modern TVs of any technology, it's the power supply that dies long before the panel. Not to mention that a TV bought today probably won't be able to be connected to anything in 22 years (just like how TVs circa 1994 are obsolete today). But that's for a different article.
Like any technology, we'll see larger, cheaper and better OLEDs from LG, at least in the short term. LG has already showed, as well as .
Samsung briefly sold OLED TVs, but it has effectively conceded the OLED TV space to LG. There are rumors that might be changing in the near-ish future, but for now it's still LG's game. Sony buys OLED panels from LG and puts their own processing and design to them. Outside the US, companies like Panasonic and Philips do the same.
One of the most interesting current LCD technologies is. These microscopic particles glow a certain color when you give them energy. Many new TVs have the photoluminescent version, with dots that glow a specific color when hit with light (usually the light from an LED backlight). These help LED LCDs achieve the deeper colors required of the aspect of .
Down the road a little farther is the electroluminescent version of this technology. No LED backlight at all; just pixels made of quantum dots. These direct-view quantum dot displays, "QLED" if you will, should offer all the benefits of OLED at even cheaper prices., since it couldn't get OLED to work in large screen sizes.
Perhaps most interesting, these aren't mutually exclusive technologies. Quantum dots (the photoluminescent version) don't really care what kind of light you give them. So you could have an OLED material creating one color of light, with quantum dots creating the other colors (instead of color filters). Maybe that would be QOLED ("Quoh-lead")? Q-DOLED ("Que-doh-lead")?
Either way, we shall see.
In the nearer future, there's. While this still uses an LCD layer, there are far, far more LEDs creating the light. Most local dimming LCDs, (i.e., pretty much all high-end LCDs on the market today) have a few hundred LEDs. The first mini-LED, , has 25,000 LEDs. The result is an image far closer to OLED, without that technology's price premium. Will we see more mini-LEDs in going forward? Probably, at least until we get , which is a completely different technology, and an even cooler one at that.
OLED displays are expensive, but their drop in price from just a few years ago is dramatic. That has leveled off somewhat, but in return they've gotten even better, with higher brightness and wider color gamut.
We've reviewed several OLED models over the years, and they consistently make fantastic-looking images. They're regularly CNET's pick for best picture quality of the year.
Would we like to see them even cheaper, and made by more than one company? Absolutely. Until then, they sure make some lovely images.
Got a question for Geoff? First, check out all the other articles he's written on topics like , , and more.