imec and Fujifilm figure out submicron patterning for full-color OLEDs
The development paves the way to producing high-resolution and large organic Electroluminescent (EL) displays and establishing cost-competitive manufacturing methods.
Organic EL displays are increasingly used for televisions, mobile devices including smartphones as well as wearable devices. Since they can be made thin and flexible, while also offering excellent response time and contrast ratio. Today’s products require organic EL displays of high pixel density, i.e. around 200 ppi for 4K televisions, 500 ppi for full HD mobile devices and even higher density for compact displays for wearable devices.
In 2013, Fujifilm and imec jointly developed photoresist technology for organic semiconductors that enables submicron patterning without damaging the organic semiconductor materials, based on photolithography capable of high-resolution patterning on large substrates. There is no need for additional capital investment since an existing i-line exposure system can be used for the new technology. This is why the technology has attracted wide attention since the development announcement with anticipation of a cost-effective way of manufacturing high-resolution organic semiconductor devices.
In the latest achievement, Fujifilm and imec produced full-color OLEDs with the photoresist technology for organic semiconductors and successfully verified their performance. Red, green and blue organic EL materials were patterned, each in the subpixel pitch of 20 μm, to create full-color OLEDs. An OLED array of 40 x 40 dots at the resolution of 640 ppi was realized and illuminated with UV rays to confirm that red, green and blue dots separately emitted light. The emission of red, green and blue lights was also confirmed in a test involving the application of voltage rather than illumination, confirming its correct performance.
The results open new opportunities, such as using the novel photolithography in a multiple patterning process. An example would be creating an OLED array that adds a fourth color to red, green and blue, as well as developing previously-unseen devices such as a new sensors that integrate OLED with the organic photodetector.
Related articles and links:
www.fujifilmholdings.com
www.imec.be
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