LG’s upcoming Signature rollable OLED display will be able to store itself away in its base when not in use thanks to flexible display technology

ppi resolutions on FMM for OLED display fabrication. Such resolutions are especially important for AR/VR applications, where high pixel densities are required due to the displays being very close to the user’s eyes. However, challenges still remain, Park

noted, especially where the super high- resolutions of UHD and AR/VR displays are concerned, where pixel size can reach 10µm or below. He explained that the thin-film transistor devices involved in display production need to be made smaller, and that laser crystallisation – the process used in the creation of amorphous thin films – needs to perform with much more uniformity than it does currently. ‘It is because the device dimension is approaching the grain size of polycrystalline silicon, therefore grain size instability becomes very sensitive, [and] so does the device eventually,’ he said.

Flexible displays Flexible displays are rising higher in the list of design priorities for consumer electronics and smart home devices, due to them enabling better product designs and novel use cases. Evidence of this can already be seen in emerging technologies such as LG’s rollable TV and Samsung’s foldable smartphone, both of which are expected to go on sale by the end of the year. Demand is also being seen for flexible displays in the automotive sector, where an increasing amount of surface area inside vehicles is now being devoted to displays – flexible displays could address this by

being integrated into the curved and shaped surfaces of a vehicle’s interior. This drive for higher-quality displays with increased functionality and new form factors will continue to push laser systems to their limits, according to Coherent’s Pätzel: ‘New materials and technologies, such as OLED, micro-LED, transparent and foldable displays, will expand the range of [laser] applications. With this, we see the trend of using shorter laser wavelengths and also the need to innovate on the laser processing strategies.’ For manufacturing flexible displays in

particular, multiple laser firms are now offering UV nanosecond-pulsed laser systems that use advanced beam shaping technology to separate the flexible displays from their glass substrate in the laser lift-off process. ‘The combination of the laser sources

with process-optimised beam profiles transforms the laser sources into a precise tool,’ said Dirk Hauschild, chief marketing officer at Limo, a developer of optics and

“New materials and technologies, such as OLED and foldable displays, will expand applications for lasers”

beam-shaping solutions. Limo’s Activation Line UV system is

used in the production of flexible, foldable and transparent OLED displays. The Limo beam shaping system uses up to eight diode-pumped solid-state laser (DPSSL) UV nanosecond sources to form a line beam focus that results in more than 30 per cent higher productivity, compared to other laser lift-off systems with the same power. The system also uses the company’s new ‘sGauss’ intensity distribution to achieve a superior depth of focus, according to Hauschild. ‘This demonstrates the high added

value that optical beam-shaping systems can bring into professional production lines,’ he added. ‘This milestone motivated our customers to continue scaling their systems to the next level and to also use our equipment for the low-temperature polycrystalline silicon process called solid- state laser annealing, instead of the typical excimer laser annealing process.’ Laser giant Trumpf also manufactures

Ultrafast lasers can be used to drill precise holes in the manufacture of fine metal masks, which are used to deposit organic RGB pixel materials in the manufacture of high-resolution displays


complete laser systems featuring line beam shaping to enable lift-off for flexible displays. These systems incorporate lasers such as those in the TruMicro Series 8000 – high-power, solid-state UV nanosecond lasers that enable the sensitive



AP Systems


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