LCD and OLED are two very different display technologies that currently coexist on the mobiles and televisions markets. There are other (older) technologies such as Plasma (TV only), but right now, most users have to choose between these two. This page will give you some knowledge about both, and will highlight the differences between them — and provide a general direction for you to decide which is best for your specific usage, and budget.
LCD, which stands for Liquid Crystal Display, is based on the idea that white light goes through a color filter (a pixel) using liquid crystals to create various colors. White llight is filtered through red, green and blue liquid crystals sub-pixels. By manipulating the electric current sent to each sub-pixel, it is possible to control how much light goes through, and therefore, control the subpixel’s color intensity. If you are curious about how millions of colors can be produced from three base colors, read this.
Black pixels are done by masking completely the white light, which turns out to be very difficult. In reality, there’s always an amount of light leakage that happens, which is why “black” is never truly black on LCD displays.
Passive vs. Active Matrix
LCD displays have been around since the 80s when they were first used in “portable” computers. Such displays have a “matrix” of pixels ( the name for a 2D array of pixels) which was either a Passive Matrix or an Active Matrix. The Active Matrix was more modern and allowed finer-grain control, and faster pixel state switching when compared to the Passive method. Active Matrix screen was first introduced using the TFT (thin-film transistor) technology, but other variants also appeared, to essentially do the same job at a better cost ratio.
All LCD displays required to have some form of backlighting from white light. Over time, different types of lighting technologies were used. The goal was to have brighter and more uniform lighting, at an ever smaller form-factor to allow thinner and lighter displays.
LCD started with cold cathode fluorescent lamps (CCFLs) lights, but modern displays typically use LED lights these days. Also, some LCDs have not only white but also colored LED lights to produce specific colors which are difficult with the basic white light setup.
Backlighting vs. edgelighting
Although the light is always coming from behind the LCD layer, most displays have lights coming from the edge of the screen, typically in the bezel – this is called edgelighting. This is so the design of the screen can be more flat.
Television that may not have such a depth constraint sometimes features an array of LED lights placed directly behind the LCD layer – this is called backlighting. This makes the lighting more uniform, and optionally more controllable with micro-dimming (shutting down lights by region).
LCD IPS and PLS
IPS stands for In-Plane Switching (also called Super TFT) and is an LCD variant. IPS was designed to provide better color accuracy over wider view angles. The first LCD displays’ color accuracy depended strongly on being right in front of the screen.
IPS displays can reproduce colors within a 178 degrees field of view (that’s the specifications for most IPS displays). IPS displays can also be touched without having the colors be affected, which is why it has become the de-facto standard for touch-devices. Yes, old LCD displays would have odd colors where your finger touched…
There are many variants of IPS technology, including Super-IPS (S-IPS), Advanced Super IPS (AS-IPS), IPS-Pro, and more. Not all IPS displays are equal, but in general, IPS-type displays are the best LCD displays.
PLS, or Plane to Line Switching, is an IPS-like technology which is proprietary to Samsung. Samsung claims better brightness and more efficient production costs, but we could not confirm this independently. LG is a leader in IPS panels.
LCD + Quantum Dots
Quantum Dots is a technology designed to improve the amount of color hues that LCD displays can produce. Quantum dots are semiconductor nanocrystals that can absorb a specific light spectrum, depending on their size. This property can be used to create/tune better shades of Red, Green, and Blue. To the user, this means that colors come out more saturated – they “pop” more.
This breakthrough has been introduced to the market recently and allows the best LCD televisions to have OLED-like color properties. At the moment, this concerns high-end TVs, but over time, we expect the technology to trickle down. Quantum dots have potential applications with anything that requires a precise control of light wavelengths, including communications.
OLED, which means Organic Light Emitting Diodes, works on the principle that each pixel is its own light source, and it doesn’t need a separate light or a colored filter. Each pixel of an OLED display is composed of a minimum of three Red, Green, Blue sub-pixels. Manufacturers have been using other base colors, such as yellow as well, but the principle remains the same.
Because of this, black pixels are simply pixels that emit no light at all. No light needs to be blocked by a filter, and there is no leakage of light at all. That’s why OLED displays can produce true “black”. The OLED black levels are so dark that the contrast ratio becomes incredibly high (for practical purposes, it is often considered “infinite”). The contrast ratio is the ratio between the brightest white and the darkest black that the display can produce.
OLED technology has evolved since their lab debuts in 1987 and has become popular and cost-efficient with the arrival of smartphones. Because OLED displays use fewer layers than their LCD counterpart, they tend to allow thinner designs, which is particularly important for mobile devices. For televisions, it depends on your preferences, but we consider that thinness is no longer a major sway factor in the OLED vs. LCD battle.
LCD vs. OLED Technology: point by point
With this fundamental difference in mind, we can explore how this affects a certain number of imaging properties for both technologies, going from the most perceptible, to the least visible.
Black Level: OLED wins
Black level designates the darkest “black” color that the screen can reproduce. Since many display technologies such as LCD, but also DLP or projection, relies on filtering or blocking a white light, making true black is extremely difficult. In fact, LCD displays cannot produce true black because the light blocking is never perfect. On the other hand, OLED can produce true black because no light is emitted at all from OLED black pixels.
Contrast Ratio: OLED wins
The contrast ratio is the ratio between the brightest white and the darkest black the display can produce (white:black). Again, because most display technologies are based on blocking light to produce blacks, LCD tends to have an advantage with high brightness (especially with HDR), while OLED has an advantage with Black Level. Overall, OLED displays tend to have a better contrast ratio, just because the math of a ratio combined with a near-zero level of black leads to a huge value.
Viewing Angle: OLED wins
While the best IPS displays could compete with the best OLED display on viewing angle, the truth is that most LCD displays are not IPS (especially for TVs, more so than for mobiles). Even if they were, they may not be the highest quality IPS (LG and Panasonic would be your go-to brands for IPS TVs).
Overall, OLED would get better view angles, which is particularly important for TVs since viewers could be a bit off to the sides, or watching at an angle while doing something.
Color Gamut: OLED wins
On paper, OLED can produce excellent color gamuts (set of colors supported), but the recent introduction of Quantum Dots has made LCD TVs just as capable. Independent reviews of the best LG OLED TVs going against the best Samsung Quantum Dot LCD TVs have shown that both technologies can compete hand to hand.
Since only the very best LCD TVs can compete, in general, OLED is the better choice for color gamut.
Brightness levels: LCD Wins
Because LCD TVs use a separate lighting apparatus, it is, in general, easier to build extremely bright LCD displays. In reality, the very best LCD and OLED TVs have brightness around 400 NIT, but in general, LCD Technology can push higher absolute brightness. Note that a higher brightness makes the image better in a bright ambient light.
And this is particularly true with HDR technology which can push brightness to 1000 or even 10000 NITS. At this moment, the best OLED HDR TVs do peak at an impressive 600 NIT of brightness, but some Sony HDR LCD TV can hit 1000 to 1300 NIT. That said, the brightness should ALWAYS be put in relation to the Black Level and Contrast Ratio.
Color Uniformity: OLED Wins
Being able to reproduce a flat color in a uniform way is a very important characteristic for any display. Because LCD displays tend to have light coming in from the edges of the screen, the uniformity is often not so great. If the light comes from an array at the back of the screen, things are better, but these are still discrete points casting a light that needs to be diffused.
On the other hand, OLED is much better because each pixel generates its own light, without the need for diffusion. In the real world, even OLED display are not perfectly uniform, because of the manufacturing, of even because the screens are curved. However, they are better than LCDs.
Power Consumption: LCD wins
At a given level of brightness, LCD tends to consume less power than OLED. It’s not new, but it’s a tradeoff that people have to accept. For mobile devices, higher brightness can mean better usability outdoors. For Televisions, higher brightness is good during daytime, although during night time, it doesn’t matter as much.
On the other hand, OLED power consumption varies depending on how many pixels are lit, which makes them great for always-on displays and screen savers.
Cost efficiency: LCD wins
At the moment, LCD is the most cost efficient display type, by far. However, OLED remains under intense research and cost-reduction efforts remain underway. It’s not clear if and when the cost ratio will cross, but OLED has a bit more potential in the long term because it can be shaped in different ways, and could be used in shock resistant or flexible devices.
Conclusion: OLED has the best image quality, but…
As you can see, OLED wins nearly every “image quality” factors. It is evident that it is a better imaging technology, but one that remains limited by the cost of production, and size limits if you want something really big.
That said, in specific use cases – involving brightness – LCDs can still make a significantly positive difference. If you want to dive in technical details, I found this article from DisplayMate about high-end LCD and OLED TVs to be interesting. Amazon has a short page that will bottom-line most of what I’ve said above about OLED and LCD, although it doesn’t offer an explanation.
At the end of the day, “budget” drives the ultimate purchase decision, which is why LCD still dominates televisions, and even mobile devices, to a lesser extent.