What is a QD-OLED TV?
QD-OLED is one of the latest acronyms to enter the consumer display market, uniting two seemingly competing systems into a single display technology. Many of the terms commonly used by manufacturers are primarily marketing tools designed to highlight the unique selling points of a specific product line. Though important to consumers, these are rarely ground-breaking. QD-OLED displays, however, could be truly revolutionary.
Combining functional quantum dots (QDs) with organic light-emitting diodes (OLEDs) has been an important area of research for years. Many companies have invested heavily in novel display panel systems that hybridize the two technologies. However, inherent material challenges and production bottlenecks have prevented each technology from progressing separately – never mind in an innovative combined format. QD-OLED displays have subsequently been considered something of an elusive goal.
Realizing high-performance QD-OLED displays would require significant re-allocation of resources and a concerted effort to utilize the latest QD formulations and OLED panels. Fortunately, large-scale manufacturers are beginning to do just that.
All You Need to Know About Quantum Dots
QDs are nanostructured semiconductors with characteristic optoelectronic properties determined by their size. When stimulated by photons, QDs become excited and emit light of characteristic wavelengths. The smallest crystals – approximately 2 nanometres (nm) in diameter – tend to emit shorter wavelengths (450 – 485 nm) which corresponds to blue light. This characteristic emission can be tuned by controlling the particle size, with the largest QDs – approximately 7 nm in diameter – emitting longer wavelengths (625 – 740 nm) corresponding to red light.
So far, QD displays have gone through an intensive series of development phases. The current leading technology is based on film-type QDs integrated into a typical liquid crystal display (LCD) matrix. Given the high peak brightness of LCDs and the unprecedented spectral capabilities of QDs, these arrays are renowned for exceptional color quality. QD-OLED displays aim to combine such impressive colour reproduction with the efficiency and enviable black levels of existing OLED panels.
Understanding OLED Panel Technology
An OLED panel is a thin stack comprising a photo-emissive, carbon-based emitter sandwiched between an anode and a cathode. When a current is induced across the array it causes the OLED material to fluoresce. The spectral properties of this light are dependent upon the composition of the emitter, though the two primary technologies yield either blue or white light. As OLED panels are self-emissive, they do not require a backlight to generate pictures onscreen. The main benefits of this are two-fold: they can be significantly more energy-efficient, and individual pixels can be switched off to produce true black pigments for infinite contrast ratios.
Today, OLED panels are one of the leading technologies for large-sized premium consumer displays. Yet they lack the brightness of premium LCDs and offer poor color gamut coverage compared to QD enhanced alternatives. Blending QDs and OLEDs into a hybrid QD-OLED display subsequently seems like the logical next step for manufacturers – yet there are still bottlenecks to overcome.
Functionalizing QD-OLED Displays
Two main formats have been suggested for QD-OLED display technologies. The first involves a complex arrangement where some emitters are based on QDs and others are based on OLEDs. This would require a fundamental re-think of how each technology is manufactured, notwithstanding overcoming several material limitations, such as the thermal instability of many QD formulations. The second seems more promising and has gained traction in recent months.
The second method involves depositing layers of red and green QD color converters into an OLED stack with a blue carbon-based emitter. The QDs convert incoming blue light into crisp reds and greens, while all the blue light visible onscreen is produced directly by the back panel. This would eliminate significant wastage associated with filtering white backlight. An existing concern is the poor efficiency of current generation blue OLED panels and concerns about the lifetime, but it could still represent a significant offset compared to traditional LCD technologies where up to 66% of all light generated can be wasted.
Read More: How & Why are QD-OLEDs Being Developed?
At Avantama, we are following the progress of these next-generation QD-OLED displays keenly and will update our readers as and when new information is made available. If you would like to learn more about the current market status, browse some of our previous articles. Otherwise, contact a member of the Avantama team directly with any questions.