Quantum Dots: Material Innovations and Commercial Applications

Perovskite quantum dots are well known for their unmatched color purity but unfortunately also for their strong tendency to degrade under humidity, temperature and blue flux due to the fact that perovskite quantum dots are based on a halide salt compositions. Over the last 7 years we have intensively worked on our green perovskite quantum dots and achieved a near- unity quantum efficiency, an FWHM of 22nm and last but not least a sufficient stability against humidity, temperature and blue flux turning our perovsite QDs commercially viable now. In this presentation we give an overview about our technical perovskite solutions for miniLED backlight films (LCD displays) and also QD pixelated color converters (QD-PCC) for microLED displays.
A color conversion film with green and red color conversion materials is needed for mini-LED based LCD displays because the traditional approach of using phosphors on-chip does not work for such displays due to technical limitations. Thus we present different color conversion films with our green perovskite QDs and different red conversion materials and show the benefits these films will bring to LCD displays and the LCD industry in general.
MicroLED displays are getting more mature and are close to market-entry but one of the main challenges is manufacturing costs due to chip mass transfer and involved pixel repair processes of red, green and blue microLEDs. Therefore the microLED industry requests green and red QD color conversion materials to be able to only use blue LED chips in the manufacturing process. Perovskite QDs also excel in this type of application due their advantageous properties including highest absorbance, lowest FWHM and highest quantum efficiency. Here we present our development status for QD-PCC materials based on green perovskite QDs including optical properties and different pixel deposition processes.

MicroLEDs have a tremendous potential for future displays. However, there are several technical challenges to overcome prior to widespread deployment of MicroLEDs. One key hurdle is developing a process to release the dies from the sapphire growth wafer. Another is a process to transfer these to the display substrate with micron-level precision and reliability. Laser processing offers several opportunities for MicroLED display production, such as Laser Lift-Off (LLO) to separate the finished MicroLEDs from the sapphire growth wafer and Laser-Induced Forward Transfer (LIFT) to move the devices from a donor to the substrate.

In this presentation, laser-based system solutions for the different manufacturing steps for microLEDs, will be presented. Integrated process control and monitoring are used to assure stable and reliable operation to ensure high throughput and low yield losses.

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Even though µ-LED manufacturing has moved forward over recent years, it is still in early development stage, resulting high costs and poor yields. Thus, finding pathways to reduce manufacturing costs and improve overall yield is of major interest to the industry. An alternative path would be to replace the solder paste in solder paste printing by plating process. To solve this issue Atotech Group has developed a new auto-catalytic tin process that can overcome the thickness limitation of existing immersion tin process. Besides that, the process allows tin deposition not only limited to copper, but also different metal stacks.

GaN microled is the key display technology for the next generation AR/MR glasses and Metaverse. Microled arrays driven by CMOS circuits are needed for GaN microdisplays and large area displays.
Several technologies can be used to hybridize the two parts. We will review the challenges for their fabrication, show solution provided such as microtube technology and recent results with hybrid bonding.

The roadmaps for MicroLED sizes are clearly indicating that future manufacturing technologies needs to be prepared for sizes down to 5 µm. Some current technologies adapted from MiniLED production are capable to process today´s MicroLED´s of around 50 µm but running into yield and basic challenges for the next generations.
Lasers are a key enabling manufacturing technology. This is because lasers have an unrivalled ability to yield smaller and more precise features at high throughput, and to work without physically damaging or overheating delicate parts.
Our presented laser processing technologies are capable to process very small MicroLED´s either from the growth (EPI) wafer, called the Laser Lift-off (LLO) or the mass transfer from temporary carriers. This is a future-proof technology approach and help MicroLED display makers to invest once, adapt a technology for the next years, and transfer the processing technologies into mass production.
We will present our latest information and results about laser processing solutions for MicroLED displays – from very small to very large displays.

Issues and experience of mini LED adapted into the display stepping to address micro LED display outlook.

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