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Pervoskite quantum dot (QDs) for mini and microLED displays

Perovskite quantum dots (PeQDs) offer ultranarrow FWHM and emission even when manufactured at low temperature with relatively high defect densities. The red PeQDs remain elusive due to instability challeges. However, the green one is already stable enough.


Avantama will be presenting exciting results at the TechBlick conference on microLEDs and Quantum Dots on 30-Nov-2022 and 2-Dec-2022, showcasing how PeQDs can deliver value as conversion films in miniLED LCDs and as color converters in microLEDs. See full agenda and register here www.TechBlick.com/microLEDs


MiniLEDs

In the first slide below, you can see a color conversion film composed of green PeQDs (by Avantama) and red KSF phosphors. The red KSF phosphors offer five ultra narrow red peaks. They are now an established solution in many backlight systems in which they are used as the red phosphor directly on the LED chip.


The unique combination (gree PeQD and red KSF phosphor) thus marries the best performance, combining narrow emission of green PeQD with narrow emission and proven stability of KSF phosphors.


The emission spectrum of the yellom color conversion sheet is shown in slide one. This sheet can be applied to LCD displays with min-LED backlights. The results are shown in slide 2. Here, one can see that the PeQD+KSF film allows 40% higher brighness when compared with a low-Cd QD-only color conversion film. It also offers a slighly wider color gamut. This proves that this is a good solution performance-wise


But the question of stability remains. This is the big challenge of perovskites. But as shown in slide 3, the Avantama PeQD/KSF film is as stable as a Apple's phosphor-only sheet under heat (60C)-humidity (90% r.H.) test. Furthermore, it shows that the film is as stable as Samsung's InP QD enhancement sheet even under light (300mW/cm2)-heat (50C) stress. This are good results showing sufficient stabiliy for commercial adoption.


MicroLEDs

Slide 4 shows the performance of pure PeQDs (without resins) as a color converter, showing no reabsorption losses, no QD quenching and very high opticl density (2 per 5um thickness) which is required to avoid leakage of blue light.


Of course the question remains how to deposit the QDs onto microLEDs. One option is photolithography. This is shown in slide 5. Of special interest will be the resin-free approach which will eliminate additional UV-curable resin which would lower OD/um ratio


The last option is to print the technique using electrohydrodynamic printing. This techniques allows <10um pixel printing! Furthermore, no resin is needed and it is an additive process.


Join us on 30-Nov-2022 and 1-Dec-2022 for a wonderful programme of talks on microLEDs and Quantum Dots from all the leaders in the field. See the full See full agenda and register here www.TechBlick.com/microLEDs




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