Holst Centre

Researchers from the Holst Center has applied spatial atomic layer deposition (sALD) to create both the semiconductor and dielectric layer in a thin-film transistor (TFT) Oxide-TFT (IGZO) display backplane - for the first time ever.

The researchers created a 200 PPI QVGA OLED display prototype on a thin PEN foil. This shows how TFTs can be produced in a low temperature process (below 200 degrees Celsius) using sALD on a cheap transparent plastic foil. The TFTs achieved a mobility of 8 cm²/V2 with channel lengths down to 1 um.

In 2016 the EU launched the PI-SCALE project, which established a European-wide roll-to-roll flexible OLED lighting pilot production line, with an aim to enable companies of all sizes to quickly and cost effectively test and scale up their flexible OLED lighting concepts. In 2018 the EU has launched a €14 million initiative within PI-SCALE called LYTEUS, which provides the expertise and capability required to progress an OLED lighting concept from an idea and into a commercialized product.

The PI-SCALE project has successfully been completed, and the Fruanhofer FEP institute now announced that following a meeting with the EU Commission representatives, it was decided that the OLED lighting pilot line services will continue to be funded, under the lead of the Fraunhofer FEP. The pilot line service will continue under the name LYTEUS.

The Netherlands based SALDtech, established in 2018 as a spinoff from the TNO institute, announced that it closed its 2^nd financing round led by Innovation Industries and BOM, Brabant Development agency.

SALDtech developed deposition tools based on the Holst Centre's Spatial Atomic Layer Deposition that can be used to produce large area ultra-thin layers with world class performance. SALDtech says it will used the investment to develop and build flexible OLED production equipment.

The Holst Centre announced that it will show several new fingerprint sensor innovations at Display Week 2019 next week. The research center will show a new high-resolution (500 PPI) under-the-display sensor that uses the Center's proprietary collimator technology as well as an in-display sensor concept that uses photolithography patterning to integrate the OLED and organic photo diodes (OPD) pixels side-by-side.

The Holst will also showcase a new over-the-display (suitable for LCDs) transparent sensor which at 70% the center says is the world's most transparent fingerprint sensor.

The Fraunhofer FEP institute, the Holst Center and other partners have developed a 15-meter long OLED lighting panel, the longer OLED device ever (beating their own 2017 record of a 10-meter OLED). This work was done as part of the Lyteus, the EU's €14 million initiative within PI-SCALE.

The partners in this project say that this is the first OLED produced using a new unique roll-to-roll (R2R) process that combines the performance of an evaporated OLED stack with solution processing of auxiliary layers.

The Fraunhofer FEP, together with VTT and the Holst Center developed a new wearable OLED lighting bracelet, one of the first one of the first flexible organic electronic product to be produced at the European PI-SCALE pilot production line.

The yellow and red OLED deposition in this prototype was performed at the Fraunhofer FPP (which can handle both sheet-to-sheet and roll-to-roll processes), while the barrier web was produced at the Holst Centre. VTT integrated the OLEDs into the bracelet. Such a bracelet, with its low power consumption, could be used as a security device, as a fashion jewelry, and more.

The Holst Centre is demonstrating a new optimized encapsulation (barrier) layer for foldable OLED panels. The new barrier is made from an organic layer sandwiched between two layers of silicon nitride (SiN). These are standard materials, but by optimizing the stack design the researchers at the Holst Centre were able to control its mechanical properties and create a much more flexible barrier.

The Holst researchers used an organic material that can withstand 400 °C and can be applied by slot-die coating. This allows the SiN layers to be deposited at 350 °C, improving their quality and ability to prevent water penetration. The Holst tested the OLED prototypes that use the new barrier for 1,000 hours (in accelerated lifetime testing) and no black spots appeared, even after 10,000 folding cycles (bending radiud 0.5 mm).

Taiwan-based Chunghwa Picture Tubes (CPT), in collaboration with European research institute imec (in the framework of the Holst Centre collaboration) have demonstrated an ultra-high resolution OLED display that was patterned using photolithography - without the need for an FMM (metal mask). A photolithography process offers a high aperture ratio, large substrate sizes and good yield control.

The prototype display that was demonstrated is a passive display with a 1400x1400 resolution (or 1250 PPI!) of side-by-side orange and green OLEDs. imec reports that preliminary lifetime investigation shows operation of each color after patterning for a few hundred hours at more than 50% of the original brightness.

The Holst Center presented a new functional demonstrator that uses the Holst' in-mold electronics (IME) technology to show new human-machine interfaces in automotive electronics and consumer appliances. One of the new technologies embedded in this demonstrator is flexible OLED lighting that is used to illuminate touch controls.

The Holst Center says that this is the first time a flexible OLED has been used to illuminate touch controls. Usually several LEDs, light guides, complex wiring and bulky PCBs are required to achieve this effect. Flexible OLED lighting provides a much easier solution with complete design freedom.

Researchers from the Holst Centre developed a new process to deposit semiconductor layers with better performance and high throughput than PVD-based process. the new process is based on scalable, atmospheric-pressure process spatial-ALD.

The Holst Centre used sALD to deposit IGZO backplanes that achieved charge carrier mobilities of 30 to 45 cm²/Vs. The researchers say that similar backplanes deposited with PVD (supttering) achieve about 10 cm²/Vs. The sALD layers also exhibited low off current, switch-on voltages around 0 V and excellent bias stress stability.