Inside The Quantum Dot

Quantum dots, a relatively new and emerging technology, are creating a buzz in the industry. Basically, when inserted into an LCD TV, quantum dots can boost the color gamut in the display, enabling vivid picture quality with relatively little capital. Quantum dots can also be used in other applications, such as solar and LED lighting.

To get a handle on the technology, Semiconductor Engineering recently talked to Michael Edelman, chief executive of Nanoco, one of the emerging players in the quantum dot business. What follows are excerpts of that conversation.

SE: What are quantum dots?

Edelman: They have been around since the mid-1980s. They are unlike the chips we hear about. These are semiconductors made using a chemical solution process. Through chemistry, we’re able to put compounds together to make compound semiconductors, which are very small. We are working between 1nm and 10nm. What’s unique about these materials is that as you change or alter the size of the compound crystal, you’ll alter the electronic properties. This, in turn, changes the optical properties. So the size determines the color that these colors fluoresce.

SE: How are quantum dots made?

Edelman: The chemistry is fairly complicated. But the capital, compared to semiconductor fabrication, is very minimal. You’re looking at chemical reactors versus semiconductor fabs. The semiconductor industry is used to dealing in the billions of dollars. That’s not the case here. There is no vacuum equipment. Inkjet could be used to deposit quantum dots on various substrates, but not in the actual manufacturing of the dots themselves. We are using chemical reactors, which are basically vessels. You are adding stuff, stirring stuff, and heating stuff. It’s a solution.

SE: Where are we in the quantum dot industry?

Edelman: We are absolutely in the infancy of the industry. We are in the beginning of what we believe is a major industry for a new set of materials.

SE: Why is the industry interested in quantum dots?

Edelman: What’s driving their adoption is the fact that they give off very, very bright, what we call monochromatic light. This is light of a narrowband, pure color light with very little energy going into it. Whenever you have a material that gives off a very bright light, where you can tune the color easily and the materials don’t require a lot energy to generate that light, people get excited.

SE: What are the applications?

Edelman: People are interested in everything from the display industry, to imaging of cancer cells, to solar and LED lighting.

SE: What are some of the challenges with quantum dots?

Edelman: The problem involves any new material that is introduced. How do you physically make enough of this new material that the industry can successfully bolt them into products? And can those products become affordable.

SE: The first big market for quantum dots is LCD TVs. To my understanding, quantum dots are sold in two forms—films and tubes. In both cases, LCD TV OEMs can simply integrate this technology into an LCD TV. In any case, what do quantum dots bring to LCD TVs?

Edelman: What quantum dots do is allow the OEM to produce very high-end, high-quality 4K color enhanced TVs. These TVs look great and go head-to-head with OLEDs in terms of color performance, but they are only a fraction of the cost. So, the clear benefit for the LCD industry is that they will get OLED-type color performance. Quantum dots have the potential of saving up to 30% in terms of power and it’s a drop in solution in most cases.

SE: Hasn’t it taken a while for quantum dots to take off?

Edelman: For us, we have been working on this with LCD companies for over six years. As one or two OEMs pioneer it and launch the technology, then everybody tends to follow.

SE: At one time, OLED TVs were supposed to dominate the high-end TV market. What about OLED TVs?

Edelman: People have been talking about OLED for a long time. But you basically have only LG now promoting it. Samsung has backed away from large-screen OLEDs and focused on quantum dots for their large LCD TVs.

SE: LCD TVs, based on quantum dots, are on the market today. But those LCD TVs are at the high-end, right? How big is that market?

Edelman: The numbers are very attractive. If you look at the numbers, it’s roughly 240 million LCD TVs being produced a year. Twenty million or so of them are very high-end and large TVs, which are greater than 55 inches. Typically, this is where quantum dot technology is starting off. This is where the OEMs tend to showcase their new technology. As the capacity comes along, it will trickle down into the other product lines.

SE: So what’s next?

Edelman: As quantum dot volumes and the capacities come on stream, you will see the technology work its way through the LCD industry in all sizes of screens, from 110 inches to your cell phones.

SE: Chinese TV makers were the early adopters for quantum dots, right?

Edelman: The technology is a great way for them to come into the market with an advanced, high-end LCD TV at a minimal cost.

SE: Any other advantages using quantum dots?

Edelman: There’s probably hundreds of billions of dollars that have been committed to LCD fabs around the world. With quantum dots, display makers don’t need to invest a lot of capital in changing their fabs.

SE: Still, there are some environmental issues with quantum dots. Europe has raised concerns. And so has China.

Edelman: The original quantum dots were based on II-VI compounds like cadmium. The majority of our competitors have cadmium-based quantum dots. Nanoco realized in 2004 that cadmium, which is heavily regulated and a highly toxic substance, is going to be difficult to get into the market in a really big way. So, Nanoco has been working for a long time to pioneer cadmium-free quantum dots.

SE: But don’t cadmium-based dots provide better performance than cadmium-free dots?

Edelman: Cadmium-based quantum dots have been around since the mid-1980s. Cadmium-free is much newer. I would say the performance gap is getting very close. We don’t see a big difference between cadmium and cadmium free. The evidence is clear. Two major OEMs, Samsung and LG, have decided that they would launch products using only cadmium-free technology. Other OEMs are also looking to move away from cadmium to cadmium free.

SE: Nanoco has a licensing deal with Dow Chemical. What does that bring to the party?

Edelman: One of the challenges that we saw in the early days was how do we supply the industry with the products it needs fast enough. So, we signed a license with Dow. That allows Dow to manufacture, market and sell quantum dots based on Nanoco’s quantum dot technology. What Dow brings to the table is scale.

SE: Quantum dots can be used in the solar industry as well, right?

Edelman: There is a lot of research going on. We have a program on thin-film nano-particles based on CIGS or copper indium gallium selenide. We make 5nm particles chemically. We then coat those. We put them into an ink and then they are coated onto a substrate. Then, they are annealed into a solar active film. That’s a program that we’ve been working on with Tokyo Electron. That program is still in the lab, but we are in the process of scaling that up.

SE: What do quantum dots bring to the solar industry?

Edelman: The value proposition here is that you have solar cells based on thin films that are very inexpensive to make. This results in a $1-per-watt figure of less than 35 cents a watt on the panel. The beauty here is that you are using very simple printing technology to get the nano-particles onto your substrate. The manufacturing facility, and the capex requirements, to make these panels are a lot lower.

SE: Are there other applications?

Edelman: We’ve already started sales in the lighting industry using quantum dots to enhance LED lightening. This is initially for niche applications. But eventually, that could be rolled out across a lot of areas.