Samsung and LG Exit the LCD Market. Quantum Dots and Organic LEDs Take the StageApril 01, 2020 by Gary Elinoff
With Samsung and LG closing production on LCDs, the two display leaders turn their sights on two newer technologies: quantum dots and OLEDs.
Samsung Displays, a unit of South Korean Samsung Electronics, will stop producing LCDs by the end of this year, according to Reuters. The company has already shut down one of its two South Korean production lines. Also affected by the change will be Samsung’s two LCD factories in China.
The move is spurred by falling global demand for LCD panels as well as by a supply glut. The company, in an effort to reassure present customers, has stated that, “We will supply ordered LCDs to our customers by the end of this year without any issues.”
A Trending Departure from LCDs
What's interesting about this announcement is Samsung's reason for moving away from LCD technology. Last October, the company announced that it plans to invest 13.1 trillion won ($10.72 billion) to produce screens based on quantum dot technology instead of LCDs.
According to Reuters, a Samsung spokesperson stated that the company has not yet decided what to do with the former LCD factories in China. Image used courtesy of Kim Hong-Ji, Reuters
Samsung isn't the only one making the transition away from LCDs, either. Another South Korean giant, LG Display is heading in a similar direction. In a statement quoted in Reuters, LG's CEO Jeong Ho-young explained, “We will be wrapping up our LCD TV production in South Korea by end of this year and focusing on our LCD TV production in China."
But rather than focusing on quantum dot displays, LG is pinning its hopes on organic light-emitting diode (OLED) technology.
In this article, we'll narrow our focus on these two new alternatives—quantum dot technology and OLEDs: what they are, how they compare to LCDs, and what devices may spin out them.
Just What is Quantum Dot Technology?
According to Samsung's explanation of quantum dot technology, a quantum dot is a manmade nanoparticle that can range in size from two to ten nanometers. Present day, production-ready quantum dots need a backlight, and usually LEDs are employed for the task.
When penetrated by light, each semiconductor-like particle emits a specific color of the visible spectrum; larger dots for the larger wavelengths like reds, and smaller dots for higher wavelengths such as violet.
Quantum dot particle size determines color. Image (modified) used courtesy of Samsung Display
Quantum LEDs or QLEDs are noted by their extreme color specificity. As such, these devices can display dazzling display colors. Samsung claims that its QLED displays can display over one billion unique colors.
What About OLEDs?
An organic light-emitting diode (OLED) is one that utilizes an organic compound as the source of electroluminescence. Unlike QLEDs, OLEDs work without a backlight because they emit visible light themselves when a voltage is applied.
Diagram of an OLED. Image used courtesy of the Universal Display Corporation
As illustrated above, an OLED is built of a stack of thin organic layers sandwiched on opposite ends by an anode and cathode.
Quantum Dots vs. Organic Light-Emitting Diodes
The color accuracy of QLED displays is maintained even at peak brightness, whereas the colors displayed by OLED displays tend to lose accuracy, or “wash out” at higher intensities. OLEDs also tend to lose color definition as they age.
Samsung claims that its QLEDS have peak intensities of 4,000 nits, a measure of light intensity high enough for viewing even under direct sunlight.
OLEDs present practical difficulties in the manufacturing processes. This may change in the future, as it is hoped that production via ink-jet methods will prove practicable.
Even now, flexible OLED screens are being produced. Most observers note that under ideal conditions, OLED displays deliver better picture quality than do QLEDs. Luckily, electrical engineers at Stanford University have found other applications for quantum dots beyond TVs.
New Technologies Made Possible by Quantum Dots
Quantum dots are extremely efficient. They are known to emit over 99% of the light they absorb. What isn’t remitted is rendered into heat, and researchers at Stanford University are using that generated heat to measure just how high quantum dot efficiency can go. Below is a diagram from a Stanford graduate's research report on "Redefining near-unity luminescence in quantum dots with photothermal threshold quantum yield."
This research has lead researchers to believe that quantum dots can efficiently reemit the light they absorb—"a telltale measure of semiconductor quality."
The diagram depicts how an electron absorbs excitation light, causing the electron to move from a low-energy state to a higher-energy state. Image used courtesy of David A. Hanifi, et. al
The investigators are hoping that efficiencies of 99.999% can be obtained. If it can, that and the sub-microscopic size of quantum dots may well enable a whole group of new technologies.
One example is the fabrication of dye particles, which will enable the tracking of biological processes that take place on the atomic scale.
Another possibility the Stanford researchers note is luminescent solar concentrators. These may allow a small amalgamation of solar cells to absorb energy from a large area of solar radiation.
With Samsung as such a dominant leader in display technology, it wouldn't be surprising to see other developers following suit in the departure from traditional LCDs.
If you work in this industry, how might this transition affect your work at the circuit level? Do you have experiences with quantum dot technology and OLEDs? If so, please share your thoughts in the comments below.