Perovskite-based quantum dots - a guest post by Ossila

What are Quantum Dots?

Quantum dots (QDs) are semiconducting nanocrystals that are very small – only a few nanometres in size. In display technologies, the most common types of QDs used are composed of a metal chalcogenide core. These QDs have the chemical formula XY – where X is a metal and Y is sulfur, tellurium or selenium (e.g. CdTe, CdSe, ZnS) – which is encased with the shell of a second semiconductor (e.g. CdSe/CdS). Their tiny dimensions mean that charge carriers are confined in close proximity, which gives QDs optical and electronic properties that are substantially different from those of large semiconductor crystals.

QLEDs vs OLEDs

In particular, QDs have enhanced light absorption and emission, making them particularly suitable for display technologies. Metal chalcogenide quantum dots (MCQDs) have already made it into commercial products – most notably, in Samsung’s QLED television range. Here, a blue LED backlight excites a layer of quantum dots on an LCD panel, causing them to emit light. The color of light emitted by the quantum dots depends on their size – with small dots emitting blue light, and progressively larger dots emitting green, yellow, orange, and red light.

Ossila QD structure imageLeft: Core-shell quantum dot structure. Right: The size of the dot defines the color of light that the dot emits. (Source: Ossila.com)

Is Apple developing perovskite-enhanced QD-LED displays?

Quantum Dots are used today in the display industry to enhance the quality and efficiency of LCD-based displays, most notably in TVs (one example is Samsung's premium QLED TV range). While these are still LCD displays enhanced by QDs, quantum dots also have the larger potential to create truly emissive displays (QD-LED) which could compete with OLEDs and even surpass them in quality, efficiency and ease of production.

Apple iPhone XS photo

Several companies (including Samsung, BOE, LG, CSoT and others) are indeed developing QD-LED displays (Samsung, interestingly, is preparing to kick-start hybrid QD-OLED TV pilot production next year). Apple is not left behind, and the company is already known to be looking into QD-LED technologies.

Quantum Materials Corp. announces a high volume production process for perovskite quantum dots

quantum Materials Corp logo imageQuantum Materials Corp., manufacturer of Cadmium-free quantum dots, recently announced it has developed a continuous flow manufacturing process to produce stable, low cost, high purity perovskite quantum dots (PQDs). Quantum Materials Corp has reportedly developed a high volume production process that produces extremely high purity PQDs with significantly improved stability.

PQDs have many unique properties that make them an ideal material for utilization in applications such as solar cells and displays. PQD-enhanced solar cells have demonstrated impressive conversion efficiencies, and as a phosphor replacement in flat panel displays, PQDs have the potential to provide industry excellent color gamut picture qualities due to their extremely narrow emission wavelength profile.

Quantum Solutions demonstrated its perovskite QDs at Displayweek 2018

Saudi Arabia-based Quantum Solutions demonstrated its perovskite quantum dots (with a focus on its green-colored ones) at SID Displayweek 2018, in addition to its Lead-Sulfide (PbS) QDs.

Quantum Solutions says it uses a flow reactor to create uniform and high-quality QDs at high yields and minimal waste. The company also develops encapsulation technology to protect the perovskite QDs. Their current materials have a lifetime of around 8,000 hours.