Next Generation Quantum Dot Pixel Based LCD Displays

AZoNano talks to Norman Luechinger, CTO of Avantama AG, about the developments of next generation QD pixel based LCD displays and other quantum dot applications.

Can you give a brief overview Avantama AG and the work you do?

Avantama AG is specialized in the development and supply of printable and coatable materials for the manufacturing of optical or electronic thin films. Avantama’s materials are based on liquid formulations and inks containing semiconducting metal oxides or luminescent perovskite quantum dots

Could you please explain the basic theory behind Quantum Dots for our readers?

Quantum dots (QD) are very small semiconductor particles, only several nanometres in size, able to luminesce with a very defined color when excited with blue or UV light. The color of existing commercial QDs such as cadmium selenide (CdSe) or indium phosphide (InP) can be tuned by controlling the QD size precisely. The narrower the particle size distribution, the narrower (and purer) the resulting color which is a prerequisite for displays with a large color gamut. These QDs require an inorganic shell (e.g. of zinc sulphide) for sufficient quantum efficiency and stability.

How do the Avantama AG quantum dots differ from existing products on the market?

Avantama’s QDs show several differences when compared to other commercial QDs (CdSe and InP), for example;

1. The chemical composition is based on metal halide perovskites such as e.g. CsPbBr3
2. The QD color is mainly controlled by the chemical composition and not by the QD size.
3. No additional inorganic shell is needed for high quantum efficiency and stability.
4. The absorbance per gram of QDs is at least 3 times higher than CdSe or InP, which is crucial for the second generation of QD TVs (QD color pixels).

What advantages do these differences provide?

Since the color tuning is mainly controlled by chemical composition, production at larger quantities is more straight forward and production costs are substantially lower. Another cost saving factor is the fact that our QDs can be synthesized in a 1-step-process at ambient conditions. This is possible because no inorganic shell needs to be deposited on the QDs nor is the QD size control critical. Our metal halide perovskite QDs yield the highest possible quantum efficiencies of > 95% which will result in best peak brightness of LCD displays. The FWHM of < 25 nm of our green QDs enables one of the purest green colors achievable by QDs which will result in best display color gamuts possible on the market. The very high intrinsic absorbance of our metal halide perovskite QDs makes them a suitable material candidate to enable the next generation QD pixel based LCD displays. In summary our metal halide perovskite QDs are the most suitable material for LCD display applications.

How do your next generation quantum dots differ from the previous generation?

Besides the advantages in optical performance as discussed in the last questions, our next generation QDs show improved thermal stability which is a condition for the next generation LCD TVs where the color filters are replaced with QDs (QD-pixel type LCD).

Image Credits: Avantama AG

What proof of concept have you applied to the next generation quantum generations?

We have proven that our next generation QDs fulfil the most important requirements of the QD-pixel based LCD displays which are currently developed by the display manufacturers, for example;

1. Best-in-class optical performance
2. High optical density of QD-pixels for blue backlight: We have achieved an optical density of 2 (only 1% of the blue backlight can pass the pixel) at at pixel film thickness of less than 5 micron
3. Baking stability of 2 hours at 150°C

Which industries will benefit from the next generation quantum dots?

Our QD innovations enable next generation LCD displays. This means that future LCD displays can create even more colors, show a further improved energy efficiency and a higher peak brightness. This will further strengthen the LCD display technology in the future making it challenging for other display technologies like OLED to become dominant in the market.

What’s next for Avantama AG?

We are currently installing a production line with an annual capacity of QDs sufficient for 2 Mio m2 of LCD displays and shipping of qualification samples is expected for Q3 2018

About Norman Luechinger, PhD

Norman earned his PhD in Chemical Engineering from the Swiss Federal Institute of Technology (ETH Zurich) after completing his materials engineering education in Zurich and Sydney/Australia. During his education Norman has developed several patent protected materials and processes. He is winner of the Quadrant Award and the ETH medal for the best doctoral thesis. Norman is in charge for the materials development at Avantama.