Ghent researchers won two VLAIO projects to further investigate the possibilities of these innovative materials. Together with established players from the industry and Flemish start-ups, they want to bring this groundbreaking research to the market and put Flanders on the map as a pioneer in the world of displays.
Quantum dots produce richer, more vibrant colors than traditional display technologies and increase the energy efficiency of image display. The advantage of these innovative materials is that they radiate or absorb adjustable colors and that you can print them very easily. This brings many advantages economically, for example because you can reduce your production costs. But equally interesting is that printable materials can be combined with many available technologies, which offers many possibilities for new applications.
Imagine if you could measure the amount of smog in the air with your smartphone camera. That you could improve your vision in fog. Or that cars would no longer start if they determined that the driver had been drinking. Since infrared light can ‘see’ through fog and smoke, can capture chemical information about the objects it interacts with and does not interfere with human vision, imaging scenes with infrared light offers remarkable advantages – as a user you have a sixth sense, as it were .
The biggest stumbling block to deploying sensors for infrared light is the cost price. If you know that a current infrared camera easily costs 25,000 euros, it is logical that car manufacturers or electronics companies do not just integrate such devices in their products.
‘The high cost price is due to the limitations of current technology,’ says UGent professor Zeger Hens. ‘An infrared camera is relatively complex because you have to combine many different materials that are rarely used, which drives up the price considerably. Precisely because you can print quantum dots, it is possible to combine different materials in a much simpler way. Just like with a normal inkjet printer, you can then print such an infrared sensor. That is much easier and cheaper than producing very diverse materials with complex technologies and combining them afterwards.’
‘With this VLAIO project, we want to make such infrared sensors affordable, so that they can also be used in everyday products. For example, they increase the range of your smartphone from the visible to the infrared, so that in addition to your visible images, you also obtain chemical information without your vision being hindered or damaged. The applications are endless. Just think of monitoring nitrogen emissions in a barn, observing gas installations to identify leaks,…’, argues Zeger Hens.
Red, blue and green light
Quantum dots also offer many opportunities when it comes to increasing the energy efficiency and colorfulness of displays. ‘If you think about how computer screens display a color image, for example, you get gray hair,’ reveals Professor Hens. ‘Actually, you create a lot of white light. You get black by placing a screen in front of that white light. Red light is created by filters, which allow red light to pass through and block the other colors, the same for green light. Optically that is very inefficient, because you throw away a lot of light.’
‘Another option is to immediately produce light in the right color where you want it,’ explains Zeger Hens. This already exists in LED displays. They are made up of thousands of pixels, each of which emits a specific color of light and thus together form a total image. But you can’t just use these displays in a watch or smartphone, because the current LEDs are much too large. ‘You can also make those elements much smaller in so-called microdisplays, where micro refers to the size of a single LED. But that’s not easy because you have to put those microscopic red, green and blue light sources all together. Each of these microLEDs consists of a different material, each made up of a different technology, and which you have to place all together in a grid. Not obvious at all.’
‘Here too, quantum dots can make a difference, because you can use them to emit light. The idea is to place microLEDs with only one basic color in these microdisplays, so that they can be made in one material. You add the other colors by printing quantum dots on top of those light sources. For example, you can make red, blue and green pixels with the same type of materials.’
With the second approved VLAIO project, the researchers want to explore the possibilities of ultraviolet as a base color, in which blue, red and green are added afterwards using quantum dots. This avenue opens up many possibilities, for example for ‘human centric lighting’, where the light spectrum of a screen or a lamp is adapted to the human circadian rhythm, say the biological day and night clock. For screens, this strategy can also mean a further increase in energy efficiency.
Collaboration between academia and industry
‘The applications of these microdisplays are endless. Just think of smartwatches that have to offer very bright, high-resolution screens, while still being affordable. That combination requires innovation in the field of materials research and the integration of those different technologies,’ adds Eva Ryckeboer. As a UGent business developer of NB-Photonics on photonics, the scope of these projects, she guides research groups in collaborations with companies. Photonics or optoelectronics focuses on the interaction between light (photons) and electrons (electronics).
‘Although a multitude of industrial partners are involved in these projects, photonics remains a domain that requires a transfer from strategic basic research to industrially oriented research and development. The partners involved in the various projects, with established names such as AMS, chemical knowledge companies such as ChemStream, knowledge and research institutions such as Imec and UGent, and start-ups such as MICLEDI and QustomDot, cover the entire value chain. This allows results at all levels to be transferred to companies and thus find their way to the consumer.’
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