These are halcyon days for TV technology. Ultra HD 4K is now established, HDR is readily available, and streaming puts a near-infinite supply of content at our fingerprints all day, every day.
But these are also confusing times for TV technology, with new acronyms and marketing terms raining down like confetti at the wedding of the managing director of a confetti company.
One of the current confusions lies in the comparison between the two technologies competing at the premium end of the TV market: OLED and QLED. So what exactly are they, what's the difference, and which is in pole position if you want the best possible picture? Allow us to fill you in.
OLED pros and cons
OLED (Organic Light-Emitting Diode) is a type of display tech that involves a carbon-based film being placed between two conductors that pass a current through and cause the film to emit a light.
What’s most important is that this light can be emitted on a pixel-by-pixel basis, so a bright white or coloured pixel can appear next to one that’s black or an entirely different colour, with neither impacting the other.
This is in direct contrast to a traditional LCD TV, which relies on a separate backlight to generate light that’s then passed through a layer of pixels.
Despite many attempts over the years, no TV with a backlight has ever managed to completely eradicate the issue of light bleeding from an intentionally bright pixel to those around it.
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Other advantages of OLED are that the panels are lighter and thinner than a typical LCD/LED arrangement, viewing angles tend to be significantly wider, and response times can be supremely quick.
The major disadvantage is that OLEDs are comparatively expensive to produce. Prices are steadily getting more realistic – thanks in no small part to LG (currently the only producer of OLED panels for TVs) selling panels to other manufacturers such as Sony, Panasonic and Philips, increasing both the amount being produced and competition in the shops – but OLED TVs still tend to be a fair bit more expensive than standard LCD models. That said, Samsung's top QLEDs are actually now pricier than many OLEDs.
For now, there isn’t an OLED TV available that’s smaller than 55in, though LG Display says there will soon be a 48-inch OLED screen available. OLEDs also struggle to reach the same peak brightness levels of the best TVs that have a dedicated backlight.
Finally, the organic nature of an OLED panel means it's potentially susceptible to image retention and even burn-in, in a similar way to the plasma TVs of old. This really doesn't seem to be a widespread problem, though. We've never had image retention problems with any of the OLEDs that we've tested (or the models that staff members have bought for use at home) and manufacturers do build in features to reduce the risk.
That said, those manufacturers do still feel the need to warn customers about the potential for image retention either in the TV's manual or as a pop-up message on first installation, so make of that what you will.
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QLED pros and cons
The one major TV manufacturer not onboard the OLED train is Samsung, which is instead promoting a rival technology called QLED.
QLED stands for Quantum-dot Light-Emitting Diode which, in theory at least, has a great deal in common with OLED, most notably that each pixel can emit its own light, in this case thanks to quantum dots - tiny semiconductor particles only a few nanometres in size.
These quantum dots are (again, in theory) capable of giving off incredibly bright, vibrant and diverse colours – even more so than OLED.
The problem is that the quantum dots in current QLED TVs do not emit their own light. Instead they simply have the light from a backlight passed through them, in just the same way that an LCD layer does on non-QLED/LED backlit sets.
Quantum dots still improve colour vibrancy and control over LCD, but this isn’t the next-gen, game-changing technology that Samsung is suggesting with its QLED branding - it’s more a refinement of a technology the company was using in 2016.
OLED’s ability to light each pixel individually gives it a distinct advantage in that regard. While overall brightness levels are undeniably lower, contrast is still incredibly impressive.
But things get really exciting when we look forward to next-gen quantum dots, which will be capable of emitting their own light. These photoluminescent quantum dots will give the TV the ability to light up and turn off individual pixels, just like an OLED set, while theoretically retaining the advantages of greater vibrancy and brightness.
Unfortunately, it looks as though TVs that utilise these new quantum dots are still quite a long way off - we'd hazard a guess at 2021 at the earliest. Samsung’s main focus for 2019 has been on improving the black levels and viewing angles of its QLED TVs.
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Samsung's 2019 TV line-up includes some ranges that use direct LED backlighting and others that use edge-lit. We’ve also seen two concepts that go a step further - one that uses a MicroLED panel for a backlight, and another with an LED backlight consisting of around 10,000 zones that can be lit individually.
In the here and now, Samsung's incremental changes to its QLEDs have been very successful. The flagship Q90R offers viewing angles not far off an OLED and impressively deep blacks.
We've also now tested a 49in QLED, the Q70R, and while this is clearly a step-down in performance from the Q90R, it's a great option at the size (remember that you can't get an OLED smaller than 55in).
Arguably, the perfect TV technology would combine the brightness and vibrancy of current QLEDs with the black performance and uncompromised contrast of OLED, and current thinking is that the next-generation, genuinely light-emitting quantum dots could offer just that – to the extent that many manufacturers, including LG, are apparently working with that in mind.
MORE: What is QLED TV?
There’s no telling how far away those next-gen QLEDs are, though, so for now a TV buyer is forced to choose which combination of strengths and compromises best suits their taste.
In 2017 our TV reviews suggested the more natural and authentic images offered by OLED just about trumped the awesome punch of QLED. But with Samsung’s 2017 range generally costing significantly less than 2017’s OLEDs, there was still a compelling case for its QLED screens.
In 2018, the fight was even closer. We put the 55in LG C8 against the Samsung Q9 and it was mighty close. While the Samsung Q9FN is perhaps the more dynamic performer, particularly with HDR content, the LG C8’s balance, consistency and effortless naturalism see it take victory by a tiny margin.
For 2019, Samsung has more or less solved two of the underlying flaws in its QLED tech by vastly improving black depth and viewing angles. That might cause you to presume that that makes the flagship Q90R better than an OLED, and it's true that for many people it will be the preferred option. But LG has stepped things up more than expected, squeezing yet more picture performance from its OLED panels with clever processing. The C9 is the pick of the company's 2019 range (the E9, W9 and R9 all offer better sound and different aesthetic but the same picture), and hasn't yet been beaten by any OLEDs models from rival manufacturers.
So, in the battle of the Samsung Q90R and LG C9, the Samsung is still the punchier, more vibrant, more dynamic performer, but the LG C9 is faultlessly natural and consistent, and its perfect blacks and contrast are still thrilling.
The long and short of it is that both TVs are utterly brilliant and we can't imagine anyone being anything other than thrilled with whichever one they buy. Pushed to hand over our own money, we'd be tempted to go for whichever model offered the better value, and at the time of writing that's the LG C9.