The Chinese manufacturer BOE has shown a 55 “” Amqled screen. This is a television based on self-emitting quantum dots, without the need for an LCD or backlight. This technology has the promise to outperform the current OLED TVs.
In a press release BOE writes that their Amqled display, or active-matrix quantum dot light-emitting diode, is considered the world’s first 55 “display with 4k resolution based on this technology. the uniformity and stability in the production process of inkjet printing of quantum dots for larger panels, which has now led to this 55 “screen that is driven by an active matrix of thin film transistors.
According to BOE, the screen can display 119 percent of the NTSC color space and has a contrast ratio of 1,000,000: 1. Such a contrast ratio corresponds to the almost infinite contrast of current OLED TVs, although the mention of the NTSC color space is somewhat remarkable, partly because this is an outdated color space.
This BOE television falls within the field of EL-QD, or electroluminescent quantum dots, where, just like OLEDs, light is emitted when current flows through them. In short, the quantum dots themselves provide light and therefore no backlight is required. Because they can also be switched off, the contrast is almost infinite, just like with OLED TVs.
Photos of the BOE television, taken from the Chinese website PJTime.
Differences from OLED
However, there are also the necessary differences with OLED. Where current consumer OLED TVs are based on white organic LEDs with color filters, BOE’s television is all about quantum dots. These are tiny two to ten nanometer crystals that can display colors based on their size. They are small semiconductor particles whose dimensions are adjusted to emit light of different wavelengths. Because inorganic materials are used for the quantum dots in BOE television, the lifespan should be relatively good.
Because there is no backlight and color filters are absent, quantum dots no longer need to convert light into another color. The latter is still the case with LCD televisions where Samsung uses the marketing term QLED. A quantum dot film is used that converts the light from the blue backlight LEDs into red and green light.
In BOE’s television, the quantum dots immediately convert the electricity into the correct frequency and thus the correct color of light. This means that color filters, which convert light into heat, can remain absent, which benefits efficiency and thus potentially the maximum achievable brightness. Furthermore, the technology is capable of a large color gamut and very good viewing angles.
Incidentally, the technology of the Amqled television also differs from the quantum dot OLED panels that Samsung Display is working on. This concerns panels with blue OLEDs and quantum dots. In addition, red and green color filters are used to create sub-pixels of those colors.
With quantum dots, there is the problem that previously good results have been achieved mainly by using cadmium. This is a heavy metal that is poisonous. With the RoHS directive, or Restriction of Hazardous Substances, the EU is trying to prevent the use of hazardous substances in electrical equipment, which also specifically aims to reduce cadmium.
Samsung seems well on its way in creating quantum dots without cadmium. Samsung’s solution, as described in a scientific paper from last year, relies on indium phosphide. Traditionally, the performance based on that chemical composition has been less good than when cadmium is used. Samsung claims to make progress in this area, although there are still issues with regard to the performance of the colors green and blue and the lifespan is not good enough.
The latter is a well-known problem: more energy is needed for green and blue in particular. As a result, these colors are more likely to wear out. LG Display has overcome this problem with its white OLEDs, so that all colors wear out equally quickly. It is not clear to what extent BOE has found a solution for this. The fact is that all screens that emit light themselves have to deal with burn-in. If the chemical effect is also not completely stable, it can go a lot faster. Samsung previously reported progress in the performance of blue quantum dot LEDs.
For the time being, BOE’s television does not seem much more than a prototype. The company also does not clarify the exact chemical composition of the quantum dots, whether cadmium has been used, what lifespan can be expected and what the maximum brightness is, for example. It is important to realize that BOE is a panel manufacturer and does not make or sell TVs itself. This will therefore at most be a prototype to demonstrate the operation of the technology applied by BOE; the television shown will certainly not be ready for production yet. It will probably be a few years before this technology ends up in consumer television.