For years, the question of which type of HDTV to get was one of the most important to consider. You could get a plasma HDTV, a CCFL-backlit LCD, or if you had the money, you could buy an LED-backlit HDTV. Now that Panasonic is out of the plasma field and CCFL LCDs are nearly extinct, LED is the obvious choice. LEDs are available in any size and price range, and now approach the performance once only seen with plasmas. There is a new technology on the horizon that might give LED a run for its money, though: OLED has the potential to overwhelmingly exceed even plasma in picture quality.
The History and Technology
In the early days of HDTVs, plasma, with its inky blacks and top-notch picture quality, was the prevalent flat-panel technology among videophiles. Gradually, thinner, more energy-efficient LCDs with CCFL backlighting, and later LED backlighting became less expensive and more capable, and started gaining ground. The difference between plasma and LCD wavered for some time, with each offering different economic and visual benefits depending on the model, price, and time in the life cycle of HDTVs. LED screens have steadily produced improved pictures, with some high-end models comparable to high-end plasmas. They've also become steadily more affordable and accessible, with LED backlighting now standard in all high-end, midrange, and even most budget screens.
These technologies are vastly different, particularly with respect to how each display is lit. Non-LED screens, often just called LCDs, use cold cathode fluorescent, or CCFL lights to illuminate the panel. LED uses arrays of light-emitting diodes (LEDs) arranged either along the edges of the panel or along the back to light it up. Edge-lit LEDs can be thinner and lighter than backlit LEDs, but backlit arrays can sometimes individually control different sections of the screen and how they're lit to make darks look darker.
CCFL-lit LCDs were common as budget and midrange screens, but many companies have moved almost completely to LED backlighting. Now you can get even budget screens that are LED-backlit, thinner, lighter, and more energy efficient than they would have been a few years ago.
In plasma HDTVs, the phosphors that create the image on the screen light up themselves, and don't require backlighting. This doesn't mean it's more efficient than backlit LCD screens, though. On the contrary, plasma panels are much heavier than both CCFL- and LED-backlit LCDs, and consume much more power.
Then there's organic light emitting diode, or OLED, technology. This new display type has barely hit HDTVs yet, but the few screens using it have been very impressive. OLEDs are, electronically, light-emitting diodes like the backlights of LED HDTVs (though in the case of OLEDs, it's a thin film of electroluminescent organic material instead of an inorganic, often gallium-based chemical), but function more like plasma cells. Each OLED generates its own color and light, meaning it can completely shut off to produce black. They can potentially produce a superior picture to plasma HDTVs while staying energy efficient like LED HDTVs. They're just extremely rare and expensive, and will remain so for a few years.
The Present: LED
I have some bad news: Plasma is dying. Panasonic has left the plasma market, leaving only Samsung and LG producing plasma HDTVs. Some of the best HDTVs we've tested in the past have been plasmas, but they're fewer and farther between with each year. The technology is still clinging to life as the choice for home theater enthusiasts, but we could see plasmas completely abandoned by HDTV makers by 2016. It's a bit of a shame. Historically, plasma HDTVs have produced the best black levels, specifically the discontinued Pioneer Kuro HDTV brand. The Kuro's screen got so satisfyingly dark that it remained a popular HDTV for enthusiasts long after Pioneer stopped making the sets.
The domination of plasma in this field, however, is over. While Panasonic's 2013 high-end plasmas, the VT60 and the ZT60 series, have produced black levels of 0.005 cd/m2 in our tests, some LED HDTVs can produce comparable results. TheVizio E550i-B2 LED-backlit LCD HDTV, for example, produces an 0.01 cd/m2 black level and a contrast ratio of 11,997:1. There's also the issue that the E550i-B2 is available, while the VT60 and ZT60 series have been discontinued and Panasonic won't make any more plasmas.
LCD HDTVs used to literally pale in comparison to plasmas, but that's just not necessarily the case anymore. Generally, a black level of 0.02 cd/m2 is considered excellent, and until a few years ago LCD HDTVs couldn't come close. Now there are LED-backlit LCD screens that can get that dark, all while consuming less power and often having a lower price than comparable (and increasingly rare) plasma screens. This isn't always the case, but the technology is capable of it. That doesn't mean it will always be the best choice, though, especially for sheer picture quality.
The Future: OLED
For the deepest of blacks, OLED will almost certainly become the new standard for high-end HDTVs once they stop being astronomically expensive. The LG 55EA9800, a curved OLED screen with a sticker price of $8,000, produced something we've never seen before in testing: perfect black. Even with other parts of the screen illuminated, black produced no light. This is sometimes referred to as an infinite contrast ratio, though it's more of a mathematically impossible contrast ratio. To calculate it, you divide the peak brightness by the black level; a black level of zero would require dividing by zero.
If other OLED HDTVs can deliver similar performance, and if HDTV manufacturers can produce OLED HDTVs that cost less than a used Ford Focus, they will replace plasma screens as cinephiles' favored displays in a few years.
The Verdict
At this point, you have three choices: buy an LED-lit LCD, plasma, or OLED HDTV. Of those choices, only two (plasma and LED) are realistic, and one of those choices is dying out. Plasma screens are much more rare and expensive than most LCD screens at this point, but if you can spend over $2,000 on an HDTV and don't mind being limited to just Samsung and LG, you can pick up one that offers some of the best picture quality available. If you can spend closer to $10,000, you could get an OLED HDTV with a potentially even better picture, but that's a much less realistic option for most users. That leaves us with LED HDTVs, the most numerous and easy-to-find HDTV type, and one that can produce a great picture.
For more HDTV shopping advice, check out How to Buy an HDTV. And for a look at the top-rated HDTVs we've tested, read The 10 Best HDTVs.