QD-OLED vs. WOLED

What Type Of OLED Should You Buy?

What Is OLED?

Before we explore the technical differences between WOLED and QD-OLED, let's answer a simple question: what is OLED? OLED stands for organic light-emitting diode. This refers to the way the TV produces light. OLED displays generate light by applying an electric charge to a layer of organic materials, which then emit light. This light is then passed through various filters to generate the colors needed.

On the other hand, LCD TVs use a non-organic backlight, which is passed through color filters to generate the final desired color on the screen. Almost all LCD TVs made in the last ten years use LED lights as a backlight. Before that, fluorescent lights were commonly used as backlights in LCD TVs.

The main difference between OLED and LED backlights is size; LEDs are relatively large, and modern TVs can have anywhere from a few dozen of them up to many thousands in Mini LED TVs. On the other hand, OLEDs are extremely small, the size of an individual pixel. These size differences make OLEDs extremely interesting for TVs, as you can control the light output of each individual subpixel. In contrast, LED TVs can only control the brightness of relatively large zones. This leads to much better contrast on OLEDs, as the brightness of each individual pixel can be controlled independently, so bright highlights can exist directly next to dark pixels.

On the other hand, since OLEDs use organic compounds, these compounds age over time and lose efficiency. Although modern TVs have many different mechanisms to compensate for this, all organic displays will eventually fade. If your display ages uniformly, you likely won't notice this, but if some areas of the screen are driven harder than the rest, you'll see darker spots on your screen. This phenomenon is commonly known as burn-in.

Read more about the differences between LED and OLED TVs.

The Problem With OLED

So why are there different types of OLED? First, a bit of a history lesson. Many of the first OLED displays on the market used a separate OLED emitter for each subpixel, so they'd have one that produces red light, one that produces green light, and one that produces blue light for each pixel. The problem with this was that the organic compounds used for each subpixel age at different rates, so over time, colors shift and fade in a phenomenon commonly called burn-in. This was generally fine for small displays on MP3 players and other small consumer electronics, but it's far from ideal for TVs.

Solution #1: White light

LG's solution to this problem was to replace the separate red, green, and blue emitters with a single layer that produces white light. This white light then passes through color filters to produce separate red, green, and blue light, and a fourth subpixel with no filter that allows the white light to pass straight through. The white OLED layer at the bottom gives the display technology its name: White OLED, or WOLED for short.

There are a few noticeable issues with this solution, though. Color filters aren't very efficient. The display takes energy to produce white light across all four subpixels, but the color filter blocks much of that light. Similar to a projector color wheel, this solution produces brighter whites but dilutes color purity. This reduces the overall color volume, and saturated colors appear dull and muted compared to bright white highlights.

The overall structure of these WOLED panels is also slightly problematic, as a lot of light is lost to the internal layers and electronic structures in place. LG Display introduced Micro Lens Array, or MLA, tech in 2023 on the LG G3 OLED. This technology aims to recapture and focus some of that lost light, resulting in a significant increase in light output without increasing the overall power draw or pushing the panels harder.

The second problem with this solution is that it doesn't even really solve the initial problem. As we've learned in our accelerated longevity test, burn-in is still a very possible issue with WOLED technology.

Solution #2: Blue light

WOLED vs. QD-OLED structure (source)

In 2022, Samsung Display entered the market with an entirely new solution. Instead of a white OLED layer with inefficient color filters, QD-OLED panels use a blue OLED layer as a light source, with Quantum Dots printed in a separate layer above it to convert blue light to red and green. Why change to blue, and why does this matter?

Unlike inefficient color filters, Quantum Dots are extremely efficient at producing light. Instead of blocking the undesired wavelengths from passing through, they absorb light from an external source and then re-emit photos at a different wavelength without needing an electric charge. Quantum Dots are far more efficient at converting light from one color to another, so the underlying OLED emissive layer doesn't have to work as hard to produce bright highlights.

Subpixel Structure

The differences mentioned above lead to a vastly different subpixel structure. Look at the two macro images below; when displaying pure white, the white subpixel on the G3 is clearly visible, but so are the red and blue ones. Conversely, the QD-OLED combines red, green, and blue subpixels to display pure white.

LG G3 OLED Subpixel Structure

Samsung S95C OLED Subpixel Structure

As you can see above, WOLED and QD-OLED displays have vastly different pixel structures. WOLED panels use rectangular pixels with four subpixels in a red, white, blue, green configuration. QD-OLEDs, on the other hand, use a triangular red, green, blue subpixel structure. The WOLED subpixel structure has remained pretty much the same over the last ten years. They've tweaked the size and shape of each subpixel over the years to improve efficiency and reduce the possibility of burn-in, but the overall structure hasn't changed.

Performance

Now that we've explored some of the technical differences between QD-OLED and WOLED technology, how do they compare? Is there a clear winner that performs better than the other? Which one should you buy?

Color Gamut

LG G3 OLED Rec. 2020 Color Gamut

Rec 2020 xy: 72.46%

Rec 2020 uv: 75.48%

Samsung S95C OLED Rec. 2020 Color Gamut

Rec 2020 xy: 86.06%

Rec 2020 ux: 91.39%

Looking at the color gamut of each display, the benefits of a quantum dot color layer are immediately apparent. QD-OLEDs like the Samsung S95C OLED can display a much wider range of colors, especially looking at the range of greens. This difference is largely due to the purity of colors, as pure colors are far more precise on QD-OLED displays.

The structures of these TVs and the different ways they drive their pixels mean there are significant differences in the purity of the colors they produce. The spectral power distribution chart is an interesting tool to evaluate the purity of a TV's colors. This chart shows the intensity of light at different wavelengths when the TV displays a white slide and is captured by our Colorimetry Research, Inc. CR-250 Spectroradiometer during the TV testing process. Looking at the SPDs of the LG G3 OLED and the Samsung S95C OLED below, the spikes of pure blue, green, and red are far more precise on the S95C. There's less noise between pure colors, as they're not diluted by the white subpixel.

LG G3 OLED Spectral Power Distribution (SPD)

Samsung S95C OLED Spectral Power Distribution (SPD)

Winner: QD-OLED.

Brightness & Color Volume

LG G3 OLED Rec. 2020 Color Volume ITP Picture

10,000 cd/m² Rec 2020 Coverage ITP: 38.9%

Samsung S95C OLED Rec. 2020 Color Volume ITP Picture

10,000 cd/m² Rec 2020 Coverage ITP: 50.5%

Brightness and color volume are two closely related aspects of a display's performance. Whereas the color gamut measurements above look at the simple range of colors a display can produce, color volume looks at how well it can produce those colors across a range of luminance levels, from dark shadow details up to the brightest highlights. QD-OLED and WOLED panels paint two very different pictures when we're talking about brightness and color volume. The extra white subpixel helps WOLED displays when showing pure white. You can see this in the color volume numbers, as the LG G3 is significantly brighter than the S95C when displaying pure white. MLA technology has a huge part to play in this, as the LG C3 OLED isn't nearly as bright.

On the other hand, QD-OLEDs only have red, green, and blue subpixels, so pure white is simply the combination of those three subpixels. When displaying saturated colors, QD-OLEDs are as much as twice as bright as their WOLED counterparts, resulting in a much more vibrant, colorful viewing experience overall.

Winner: WOLED for pure whites, QD-OLED in general.

Reflections

LG G3 OLED Bright Room - Off Reflections Photo

Total Reflections: 0.9%

Indirect Reflections: 0.6%

Calculated Direct Reflections: 0.3%

Samsung S95C OLED Rec. 2020 Color Volume ITP Picture

Total Reflections: 1.0%

Indirect Reflections: 0.7%

Calculated Direct Reflections: 0.4%

Although it's not very evident in the photo above, there's a clear difference in how QD-OLED and WOLED TVs handle reflections. Both panel types feature glossy anti-reflective coatings that significantly reduce the intensity of direct reflections, which is great if you're in a bright room. QD-OLEDs like the Samsung S95C OLED and the Sony A95L OLED have a purple tint, which can be distracting if you're in a room with ambient light. The panel structure causes this purple tint, as QD-OLED panels lack a polarizing layer. This structure raises the amount of ambient light that bounces off the internal structure, and we can measure this.

It seems like this is an intentional decision by the panel manufacturer, Samsung Display, as a way to boost brightness. Since this is coming like this from the panel manufacturer, all QD-OLED displays have this issue. It's possible that manufacturers could add additional anti-reflective coatings to reduce this issue. The Samsung S95D OLED, for example, features a matte anti-reflective coating that significantly reduces reflections, but it's unclear if it'll also reduce the purple tint issue.

Winner: WOLED.

Uniformity

LG G3 OLED - Gray Uniformity

50% Std. Dev: 1.184%

50% DSE: 0.131%

Samsung S95C OLED - Gray Uniformity

50% Std. Dev: 1.396%

50% DSE: 0.117%

Although almost all OLEDs have fantastic uniformity, there are a few issues worth mentioning, as there are differences between QD-OLED and WOLED displays. Although our gray uniformity testing doesn't usually capture these issues, there have been widespread reports of multiple issues affecting LG WOLED displays in recent years. The issues reported include a slight pink tint, especially at the sides of the screen, as well as a grid-like pattern visible on some units.

Although these issues are noticeable on test patterns like the above gray slide, they're rarely noticeable on either QD-OLED or WOLED panels, so you shouldn't worry about it.

Winner: QD-OLED, but only slightly.

Burn-In

LG G3 OLED - 8-month update

Samsung S95C OLED - 8-month update

We've been running some of the latest OLED panels on our long-term accelerated longevity test for over eight months, and we've seen some interesting results. Although the first generation QD-OLED used in the Samsung S95B OLED developed permanent image retention very quickly, the newer Samsung S95C OLED appears far more resilient. After eight months, the S95C shows almost no sign of image retention, whereas the latest, greatest WOLED panel used in the LG G3 OLED already shows severe image retention. So it's clear that the newer S95C OLED is more resilient than both 1st generation QD-OLED and the latest WOLED panels, but it's unclear why exactly this is. Samsung Display has made changes to the panel itself that they claim improves durability, but some significant software changes to the S95C also appear to have a significant impact at reducing the possibility of burn-in.

Now, it's worth pointing out that our test is an extreme case. Two months of runtime on our test is the equivalent of watching about four hours of CNN per day for about eight months without ever changing channels or watching anything else. As long you watch varied content and don't leave static elements visible on the screen for long periods, you shouldn't have any issues with either panel type.

One of the big questions that remains to be answered: how each brand and panel type handles compensation cycles. After we posted our first 2-month update, Samsung Electronics released a firmware update for the S95B to change how the large compensation cycle was triggered. This large compensation cycle used to run only when the user manually ran it from the TV's menus, but they changed it to run automatically after about 2,000 hours. It's clear from our before and after pictures that this compensation cycle is extremely effective at reducing the appearance of burn-in, but it's unclear how it achieves this. If it's just hiding burn-in by decreasing the brightness of the rest of the screen to hide the issue, we'll see a gradual brightness decrease over time.

Winner: Too early to call. You can find the latest updates on our longevity test here.

Conclusion

So, now that we've covered the differences in technology and the pros and cons of each panel type, which one's best, and what should you buy? Overall, QD-OLED seems to be on a path to being declared the winner, but there are still some noticeable downsides. If you often watch TV in a bright room, the superior reflection handling and higher peak brightness of pure whites on WOLED panels make them a clear winner. The overall performance of each TV is more important than the specific panel used, and due to differences in specific panels, the best one overall depends on the individual TV. For lower-end or mid-tier OLED TVs, QD-OLED seems slightly better, but higher-end WOLED panels with MLA deliver significantly brighter highlights and better reflection handling.