OLED vs Mini LED: The battle of the premium panel technologies
What’s the difference between an OLED and a Mini LED TV, how do they work and which is better?
If you’re thinking of buying a mid- to higher-range 4K HDR TV you’ll probably be looking at an OLED or a Mini LED model. But what do those terms mean? Join me as we take a deep dive into these TV display technologies, and find out all about their strengths and weaknesses.
OLED vs Mini LED: What is OLED?
OLED stands for Organic Light-Emitting Diode, but since that probably doesn’t help much let’s break it down further. A diode is simply a component that conducts electricity, and if you combine it with something that glows when a charge is passed through it, you create a light-emitting diode.
In the case of OLED, that something is an organic compound of carbon-based materials that are electroluminescent, so when an electrical charge is applied they glow. If you then take this compound and sandwich it between a thin-film transistor to provide the electrical charge and a glass filter at the front you’ve created an OLED panel. The limited number of components in an OLED TV is one reason why they’re so thin, but the other is that because the technology is self-emissive there’s no need for a backlight.
The self-emissive nature of OLED has another advantage beyond the depth of the panel. Since each pixel only glows when an electrical current is applied, if you switch off that current it immediately stops glowing, thus creating absolute black with no light spill or afterglow.
Until recently the main type of panel used was WRGB OLED, which stands for White, Red, Green and Blue. This design uses an OLED that produces white light and then applies colour filters to create red, green and blue, along with an additional fourth sub-pixel for white.
This approach bypasses a problem where the organic compound used to create the colour of blue decays faster than those for red and green, while the extra white sub-pixel increases the overall brightness of the OLED panel. One TV we’ve reviewed that makes use of a WRGB OLED panel is the Philips OLED809.
In recent years this WRGB OLED design has been refined by adding thousands of microscopic lenses to each pixel. This is called a Micro Lens Array (MLA) OLED, and the addition of these microscopic lenses helps direct the light emitted by each pixel in a more focused fashion. It’s used in several flagship models from big-name manufacturers, including the Panasonic Z95A and LG G4.
MLA not only improves the efficiency of a WRGB OLED, boosting its peak brightness towards 2,000 nits on specular highlights, but does so without needing to drive the panel harder, and thus reduces the risk of image retention or permanent screen burn. Although WRGB has dominated OLED for the last decade, it isn’t the only game in town.
QD (Quantum Dot) OLED TVs such as the Samsung S95D use a panel that employs multiple layers of blue OLED material to get around the decay issue. Each pixel is composed of three sub-pixels: a blue sub-pixel consisting of the original blue light, along with red and green sub-pixels created with quantum dot filters.
Since this approach doesn’t use a regular colour filter and quantum dots are more efficient, the result is an image with a wider colour gamut and impressively bright peak highlights. In fact, in testing, QD OLED TVs can compete with MLA OLED in terms of peak brightness, but also deliver a native colour gamut that covers over 80% of the larger BT.2020 standard.
OLED vs Mini LED: What is Mini LED?
Before I explain how Mini LED works there’s something I want to make clear because certain TV manufacturers have often been rather disingenuous in their marketing. Regardless of whether it’s an LED, QLED or Mini LED TV, they all use LCD panels. They may have an LED backlight or quantum dots for improved colour performance, but ultimately it’s still LCD technology.
So what is LCD? Well, a Liquid Crystal Display uses a panel composed of up to six layers, with a backlight, glass substrates containing a liquid crystal layer, a thin-film transistor and a polarising filter. As a result, the panel has to be fairly deep to accommodate these various components.
There are two main types of LCD panels: VA (vertical alignment) like those found on the Samsung CU7100 and IPS (in-plane switching). The former is designed to deliver better native black levels, but suffers from very narrow optimal viewing angles, while the latter has wider viewing angles but poor blacks and contrast performance.
The liquid crystal layer can be transparent or opaque depending on whether an electrical current is applied but doesn’t generate light of its own like an OLED does. As a result, an LCD TV requires a backlight behind the panel to illuminate the image created by the liquid crystal layer.
Initially, LCD TVs used CCFL backlights, which were effectively a series of fluorescent tubes. This resulted in good light uniformity but fairly chunky panels. The adoption of LED backlights has revolutionised the TV market, not least because they’re a more efficient method of illumination.
Often marketed as LED TVs, this type of backlight uses rows of LEDs, either along the edges of the panel or directly behind. It’s worth noting that a QLED TV is still an LCD TV with an LED backlight, but adds quantum dot filters on the LEDs for richer and brighter colours.
Edge-lit TVs bounce the light from the LEDs off a mirrored surface behind the LCD layer, keeping the panel thinner but often creating clouding and uniformity issues in the process. The alternative, which is found on the TCL C655K, puts LEDs directly behind the LCD layer, helping with uniformity but also making the panel deeper.
Unfortunately, neither approach directly addresses one of the main weaknesses of an LCD TV – the backlight still has to pass through the liquid crystal layer, making it difficult for this type of display technology to deliver deep blacks.
Luckily LEDs can be dimmed or even turned off, which helps with perceived black levels and overall contrast. Some TVs use what’s called global dimming in which all the LEDs are turned off when showing black, but this doesn’t help much with images composed of dark and light areas.
The solution is local dimming where the backlight is broken up into independently controllable zones where the dark areas are turned off and the brighter areas are left on. A local dimming algorithm analyses the image, adjusting the zones accordingly, and the more zones at its disposal, the better the results.
Too few zones and you get what’s called blooming, which is a glow around bright objects against a dark background. This is where Mini LED TVs come in. The development of much smaller LEDs not only allows for thinner panels but also enables manufacturers to use thousands of them in the backlight.
A Mini LED TV still uses an LCD panel with a direct LED backlight but generally includes far more dimming zones than earlier LED TVs, often running into the hundreds if not thousands. This allows for significantly more independent zones with more precise dimming control and improved contrast. Two of the most recent examples we’ve reviewed are the Hisense U8N and TCL Q9BK.
OLED vs Mini LED: What is Micro LED?
Mini LED should not be confused with Micro LED, which is a completely different display technology. Micro LED is self-emissive much like OLED, but instead of organic compounds, each pixel is composed of minute red, green and blue LEDs. This type of display is currently very expensive to produce but has the potential to offer the best of both worlds by combining the strengths of OLED and Mini LED with none of their weaknesses.
OLED vs Mini LED: Which is better for certain features?
OLED vs Mini LED: Brightness
In the past, the brightness of a TV was largely moot because, regardless of the display being used, it was easily capable of delivering the 120 nits target used for standard dynamic range (SDR).
This all changed with the advent of high dynamic range (HDR), which saw content being graded with a peak luminance of at least 1,000 nits and sometimes up to 4,000 nits. Suddenly how bright a display was became increasingly more important, and it’s an area where Mini LED has an inherent advantage with many recent models hitting over 3,000 nits on a 10% window.
However, this is less of an issue than it might at first appear, partly because MLA and QD OLEDs are now hitting luminance peaks of nearly 2,000 nits, but also because a lot of content is currently only graded at 1,000 nits. It’s also worth remembering that these peak brightness numbers only relate to specular highlights rather than the entire image.
This is an area where an OLED has limitations when compared to a Mini LED, often struggling when rendering a bright full-screen image in HDR. Why? Because when energising its entire panel, an OLED TV’s automatic brightness limiter kicks in. As a result, a full-field white pattern on an OLED won’t reach more than 350 nits, whereas a Mini LED TV can easily hit over 700 nits.
TV manufacturers seem to be squeezing more brightness out of their OLED panels with each successive year, and it’s possible they could also reach as high as 3,000 nits. However, in discussions with TV manufacturers, I have been told the limiting factor is the possibility of increased image retention or even screen burn as a result of OLED panels being pushed too hard.
Winner: Mini LED
OLED vs Mini LED: Black levels
Of course, being able to reach high luminance levels is only half the picture because dynamic range is all about the difference between absolute black and peak white. The wider that difference, the higher the dynamic range and the greater the overall contrast performance.
When it comes to black levels the self-emissive nature of OLED gives this type of display an inherent advantage over LCD. The latter has tried to emulate OLED using VA panels for deeper native black levels and dimmable zones for better contrast performance, but Mini LED still struggles to compete with OLED in this area.
This is also true of detail just above black because if the local dimming is applied aggressively in an attempt to deepen the black levels, this can result in crushed shadows. The ability to render greater latitude in the darker parts of an image is one of the benefits of HDR and remains an area where OLED has a clear advantage. It can’t be understated how important contrast is to an image; it’s what gives it depth and punch. It’s also why OLED TVs often look better than Mini LED TVs despite not being as bright, the perceived contrast between the darker and brighter parts of an image is more pronounced.
Winner: OLED
OLED vs Mini LED: Specular highlights
It’s a common conception that HDR is all about a bright picture, but this isn’t true. If you were looking at full-frame images at 1,000 or 4,000 nits, the only thing you’d get would be a headache.
The reality is the super-bright parts of the image are reserved for the specular highlights. These are small points of light such as the glint of a chrome bumper, the sun reflecting off waves or an explosion detonating. The more precisely you can render these highlights the better.
The self-emissive nature of OLED TVs means they can control each pixel individually, allowing them to deliver precise specular highlights. When you combine deep blacks with these bright but precisely rendered highlights, you get a huge dynamic range and superior contrast performance.
To put this in perspective, since a 4K OLED is controlling each pixel individually that essentially equates to over eight million dimmable zones. As a result, even the best Mini LED TVs have a long way to go before the number of dimmable zones gets anywhere near the capabilities of an OLED TV.
Winner: OLED
OLED vs Mini LED: Colour gamut
The final aspect of HDR that has fundamentally changed how video images are produced and delivered is the colour gamut. SDR uses the BT.709 colour gamut that was developed for high-definition television, while HDR is based on the much wider colour gamut of BT.2020.
Currently, all film and TV production uses a colour gamut called DCI-P3, which was developed for digital cinemas and is wider than BT.709 but not as large as BT.2020. In terms of delivering DCI-P3, there isn’t much of a difference between the best OLED and Mini LED TVs, with both able to cover between 95 and 100% of DCI-P3.
The exception is QD OLED, which covers about 112% of DCI-P3, although this advantage is currently redundant. However, some game developers are talking about using colour gamuts beyond DCI-P3, which means gamers may get a chance to use the full capabilities of QD OLED. Great news for people who want a TV for gaming.
Winner: Tie
OLED vs Mini LED: Viewing angles
Since the light generated by an OLED panel doesn’t have to pass through an LCD layer, the optimal viewing angles are significantly wider. As a result, an OLED TV doesn’t suffer from a drop-off in contrast or colour when viewed at extreme angles (both horizontally and vertically), which means no matter where you’re sitting in the room, you’ll be watching an optimal picture.
This is a definite issue for Mini LED TVs, especially if they use a VA panel for deeper native black levels. While improvements in viewing angles have been made, you only get optimal performance with a VA panel when positioned directly in front of the screen. If it’s just you that’s not an issue, but it might get annoying for a large family.
If you really need wider viewing angles you could opt for a Mini LED TV that uses an IPS panel, but then you’ll be sacrificing the black level and contrast performance. Ultimately it’s up to you, but there’s no denying viewing angles are an area where OLED TVs are noticeably better.
Winner: OLED
OLED vs Mini LED: Image retention and screen burn
Image retention and screen burn are areas where the opposite is true, with Mini LED TVs superior in this regard. These problems don’t affect LCD panels, and it’s one of the main reasons why the technology is popular with gamers.
The self-emissive nature of OLED means it can potentially suffer from image retention and even screen burn. This is where a static image like a heads-up display in a game is temporarily, or in the worst cases permanently burnt into the screen.
It was certainly a major problem with early OLED TVs, but thankfully over the last decade, manufacturers have introduced numerous features to successfully mitigate the issue. It’s still something potential buyers should be aware of, especially if they’re prone to marathon gaming sessions, but as long as you’re sensible you shouldn’t have any problems with a modern OLED.
Winner: Mini LED
OLED vs Mini LED: Input lag
This is an area where OLED TVs theoretically have an advantage due to their very fast response times. This allows them to refresh each image quicker than a competing LCD TV. But in reality, both use sample and hold technology to keep images on screen until the next frame is displayed, so the actual response times are about the same. As a result, both OLED and Mini LED TVs support higher frame rates up to 144Hz and also offer incredibly low input lags that are regularly measured under 10ms. This makes both TV technologies great for anyone looking for a smooth and responsive gaming experience.
Winner: Tie
OLED vs Mini LED: Design
OLED has an obvious advantage here due to its thinner panel allowing for some very sleek and contemporary styling. However, there are limitations to how slim an OLED can go because space is still required for electronics, connections and especially speakers.
In recent years LCD TVs have made significant gains in narrowing the panel depth through the use of LEDs and more recently Mini LEDs. As a result, the difference in panel depth between high-end OLED and Mini LED TVs is minimal these days, with both offering designs that are attractive, minimalist and contemporary.
Winner: Tie
OLED vs Mini LED: Price
The higher-end models from the more established brands are fairly similar in terms of pricing regardless of whether they use OLED or Mini LED. However, some of the newer brands are offering Mini LED TVs at very competitive prices without skimping on zone counts and features. We’ve got a roundup of the best TVs under £500 if price is your biggest concern.
Winner: Mini LED
OLED vs Mini LED: Which one is best for you?
As you can see from the comparison across various features and traits above, there are pros and cons to both OLED and Mini LED TVs. So the answer to which is best for you depends on where your priorities lie.
If you’re a big film fan who prioritises picture quality above all else, I’d recommend choosing an OLED. The superior contrast performance will ensure the most cinematic experience when watching your favourite movies.
Conversely, gamers will probably prefer a Mini LED TV with its bright and punchy picture, along with no worries about image retention or screen burn. But these are generalisations, so the best approach is to read our reviews of specific models and make your decision based on how well the individual TV meets your needs.
