QLED and OLED may have similar names, but they're totally different technologies. QLED refers to an LED TV using quantum dots to enhance its performance. OLED TVs have received high praise from tech journalists and reviewers across the board, including Digital Trends. For those reasons – and, let’s face it: the word QLED sounds and looks a lot like OLED — it’s important to compare the merits of these dueling display technologies in a QLED vs. OLED comparison. As always, Digital Trends is here to lay it all out for you. First, we’ll discuss what QLED is — and isn’t — and then we will pit the two technologies against each other in a point-by-point battle for supremacy.
 
WHAT IS QLED?
Generally speaking, QLED TVs are just LED TVs that use quantum dots to enhance performance in key picture quality areas. Samsung, however, claims its QLED TVs are special, offering brightness levels that meet and exceed any competing TV technology, and better black levels than other LED TVs, and can reproduce more colors than LED TVs without quantum dots.
 
WHAT QLED IS NOT
QLED is not an emissive display technology, like plasma, OLED, or MicroLED. Quantum dots don’t directly emit the colors you see; they’re spread on a piece of film that acts almost as a filter within an LED TV panel. LED backlights beam through this film, the light is refined to an ideal color temperature, and from there, brightness and color are significantly enhanced.
 
WHAT IS OLED?
OLED stands for organic light-emitting diode. Very simply put, OLEDs are made with organic compounds that light up when fed electricity – hence the term emissive display. A single OLED is the size of one pixel, so it takes millions of them lighting up and shutting off independently to fill your TV screen. Because of this flexibility, when an OLED TV’s pixels are shut off, they are completely off and appear completely black. While QLED TVs can be made very thin, OLED TVs can be made even thinner, and even flexible.
 
QLED VS. OLED
Now we’ll pit the two technologies against each other on a point-by-point basis and see how they stack up in terms of contrast, viewing angle, brightness, and other performance considerations.
BLACK LEVEL
A display’s ability to produce deep, dark blacks is arguably the most important factor in achieving an excellent picture quality. Deeper blacks allow for higher contrast and richer colors (among other things) and, thus, a more realistic and dazzling image. When it comes to black levels, OLED reigns as the undisputed champion.
 
QLED TVs improve on LED display black level performance, but they still rely on backlights shining behind an LCD panel. Even with advanced dimming technology, which selectively dims LEDs that don’t need to be on at full blast, QLED TVs still suffer from an effect called “light bleed,” the backlight spills through on what is supposed to be a black section of the screen. This effect is noticeable in scenes with bright stars on a night sky, or in the letterbox bars at the top and bottom of a movie. The result is a slight haze or halo around bright objects which blurs lines that should be sharp.
 
Source: www.digitaltrends.com