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EHDJet printed QDs on microLEDs with 15um pitch for >1000PPI displays

high-PPI RGB microLEDs, printed electronics, and quantum dots? The three themes are closely linked since QDs can be digitally printed as color conversation materials atop blue microLEDs to enable wide color gamut RGB uLED displays without requiring a separate transfer step for each color. Join TechBlick's event on microLEDs to learn more

Inkjet is the common technology investigated for such a purpose. As shown below by Armin Wedel, however, its 4pL droplet is too large, allowing at best a 40um pixel and not able to reach even 850 dpi

Electrohydrodynamic printing (EHD) can however address this issue. In EHD, the droplets are pulled out by an electric field from a nozzle which sits close (50um or so) to the surface and thus requires a good printing facility.

As shown below, the droplet volume is only 0.5pL, enabling 1-10um pixels in the lab and 15um reproducibly. This will enable one to achieve 850ppi and 1000ppi!

Slide 2 shows an example of a QD color filter (QD-CF) for a microLED display deposited using EHDJet. Here, 15um pitch is reported, achieving 1000ppi. The roadmap will be to evolve the technology towards even 2000ppi!

Of course, EHDJet is a relatively new technology. It is mainly single head and slow, although multi-head print heads are emerging. Nonetheless, it is an elegant solution for depositing color filters on high-PPI microLED displays.

To learn the latest about these technologies joint TechBlick's specialist event on microLEDs and Quantum Dots where Prof. Wedel will also present:

You can hear from the likes of Samsung, Sharp, Yole, ASMP, Coherent, Nanosys, CEA, AUO, Allos Semiconductor, KIMM, Luxnour, Omdia, Playnitride, micromac, and many many more


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