Everything You Need to Know About OLEDs, Quantum Dots & iPhone, Part I

Paul Gagnon, IHS

A new LCD display technology for 4K UHD is called Quantum Dots. On the other hand, Organic LEDs are often mentioned as a next generation technology for iPhone displays. I interviewed Paul Gagnon, Director of TV Research at IHS Technology to find out more about these two technologies and possible use in Apple's future iPhone.


There are two next generation display technologies that we often hear discussed. The first, in the context of 4K UHDTVs is Quantum Dots. It's an exotic sounding name, but it's really just a next generation LCD technology that better constrains electrons, leading to better and brighter colors.

The second is organic Light Emitting Diodes or OLEDs. This is basically an organic semiconductor that emits light when a current is applied. OLEDs remain very expensive, per surface area, compared to LCD displays, and so they're most often mentioned in the context of our small smartphone displays.

Recently, I had the pleasure of chatting with IHS's Paul Gagnon (pronounced gan'-yon), and he answered some questions I've had for a long time.

TMO's John Martellaro: I've only learned a little about Quantum Dots so far. How do they work?

Paul Gagnon Basically the way Quantum Dots work is that they are activated by a blue wavelength of light, blue LEDs, and then the Quantum Dot material, of different size for each of the three major wavelengths, emits red or green light. The blue passes through. So depending on the size of the Quantum Dots, the manufacturer can tune it precisely and mate it with the color filter used. The result is a very pure light, that is, a very narrow frequency range of the three colors.

TMO: Is that to obtain a desirable color gamut?

PG: Yes. It improves the color gamut and color accuracy.

TMO: How do the Quantum Dots start their lives?

PG: The Quantum Dot material originally comes in a liquid form. Then the manufacturer either applies the solution in a very thin layer, a film, that's placed against the backlight. Or it can be used to coat the inside of a glass tube, and then they put that into, say edge light devices.

TMO: With respect to TV displays, do Quantum Dots work better with matrix lighting than with edge lighting?

PG: The two approaches have their pros and cons. The matrix approach is better suited to large displays, TV-sized applications.

TMO: How much more expensive is a Quantum Dot-based TV display than a standard LCD display, relatively speaking? A factor of two?

PG: No, not that high. In the case of most large format displays, a Quantum Dot display ends up being about 20 percent more expensive. However, in the last year, there's been a great amount manufacturing and cost efficiency introduced. So the cost premium is coming down. That's why, at CES this year, many of the TV manufacturers announced Quantum Dot technology.

TMO: So how does the Quantum Dot technology compare to Organic LEDs? (pronounced oh'led. Like Olaf.)

PG: With Quantum Dots the basic issue is solving a particular problem: the color performance. Whereas, OLEDs hav a host of other benefits as well.

TMO: Namely, being brighter? [for equal areas]

PG: Actually OLEDs are less bright by comparison.

TMO: Does that hinder their use with High Dynamic Range (HDR) technology?

PG: It does, actually! When the UHD Alliance announced their Ultra HD Premium specification at CES, they offered two different brightness ranges for compliance with HDR. One of the brightness ranges specifies a peak brightness of 1,000 nits. [A nit is one candela per square meter]. And then a minimum black level of 0.05 nits.

The alternate specification is a peak brightness of 540 nits—but ... a minimum black level of 0.0005 nits. This one is suited for OLED, and the first one is suited for LCDs. That's because LCDs cannot get as deep a black level. There is always some light leakage of the backlighting in an LCD. On the other hand, OLED emits its own light, and so you can completely cut the power to a single pixel. But, in the end, the important thing is the dynamic range-the span from bright to dark.

TMO: Because OLEDs are self-illuminating, is the net power required lower than LCDs—because there's no backlighting required? [You can see I'm thinking about iPhones down the road here.]

PG: Ahhhh, that's a very interesting point because it depends on the content. If you are looking at a mostly white display, OLEDs have a slightly higher power consumption than LCDs. But if it's a mostly dark display, then OLED's have less power consumption. This has been one of the issues when adopting OLEDs for, say, PC applications. For example, an Excel spreadsheet or a Web browser has a mostly white background.

TMO: And..., as I recall, OLEDs remain more expensive.

PG: Yes. In the case of the most expensive Quantum Dot TV, it's still going to be less expensive than an equivalent OLED TV. The OLED TV will be least 50 percent more. Sometimes up to 2x, depending on the screen.

In Part II, I ask Paul about the future of each technology, relative benfits, and the applicability to the iPhone.


Teaser image via Shutterstock.