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Samsung Building Large "Metaphotonic" OLED Displays To Test The Viability Of Stanford’s 10,000 PPI Invention
Stanford researchers and collaborators in Korea have developed a new architecture for OLED displays that could enable television and smartphones to support resolutions of up to 10,000 pixels per inch (PPI). They expect high-pixel-density provides stunning images with true-to-life detail. Micro OLEDs are ready support 3000 ppi. The advance is based on research by Stanford University Mark Brongersma in collaboration with the Samsung Advanced Institute of Technology (SAIT). "We've taken advantage of the fact that, on the nanoscale, light can flow around objects like water," said Brongersma, who is a professor of materials science and engineering and senior author of the Oct. 22 Science paper detailing this research. "The field of nanoscale photonics keeps bringing new surprises and now we're starting to impact real technologies. Our designs worked really well for solar cells and now we have a chance to impact next generation displays." In addition to having a record-setting pixel density the new "metaphotonic" OLED displays would also be brighter and have better color accuracy than existing versions, and they'd be much easier and cost-effective to produce as well.
OLED displays were on the mind of Won-Jae Joo, a SAIT scientist, when he visited Stanford from 2016 to 2018. During that time, Joo listened to a presentation by Stanford graduate student Majid Esfandyarpour about an ultrathin solar cell technology he was developing in Brongersma's lab and realized it had applications beyond renewable energy. "Professor Brongersma's research themes were all very academically profound and were like hidden gems for me as an engineer and researcher at Samsung Electronics," said Joo, who is lead author of the Science paper. Joo approached Esfandyarpour after the presentation with his idea, which led to a collaboration between researchers at Stanford, SAI and Hanyang University in Korea. "It was quite exciting to see that a problem that we have already thought about in a different context can have such an important impact on OLED displays," said Esfandyarpour. Samsung had given up trying to pattern side-by-side RGB in large displays in 2015 and left the field to. LG. The crucial innovation behind both the solar panel and the new OLED is a base layer of reflective metal with nanoscale (smaller than microscopic) corrugations, called an optical metasurface. The metasurface can manipulate the reflective properties of light and thereby allow the different colors to resonate in the pixels. These resonances are key to facilitating effective light extraction from the OLEDs. "This is akin to the way musical instruments use acoustic resonances to produce beautiful and easily audible tones," said Brongersma, who conducted this research as part of the Geballe Laboratory for Advanced Materials at Stanford.
In conventional RGB-OLEDs, sub-pixels have different heights. In order to create a flat screen overall, the materials deposited above the emitters have to be laid down in unequal thicknesses. Manufacturers take advantage of these difference using micro-cavities to increase the light output. By contrast, in the proposed OLEDs, the base layer corrugations allow each pixel to be the same height and this facilitates a simpler process for large-scale as well as micro-scale fabrication. In lab tests, the researchers successfully produced miniature proof-of-concept pixels. Compared with color-filtered white-OLEDs (which are used in OLED televisions) these pixels had a higher color purity and a twofold increase in luminescence efficiency -- a measure of how bright the screen is compared to how much energy it uses. They also allow for an ultrahigh pixel density of 10,000 pixels-per-inch. Samsung is trying to implement the solution on a large display, while Brongersma awaits the results, hoping to be among the first people to see the meta-OLED display in action.
Figure 1: 10,000 ppi Using Metaphotonic Technology
Stanford researchers and collaborators in Korea have developed a new architecture for OLED displays that could enable television and smartphones to support resolutions of up to 10,000 pixels per inch (PPI). They expect high-pixel-density provides stunning images with true-to-life detail. Micro OLEDs are ready support 3000 ppi. The advance is based on research by Stanford University Mark Brongersma in collaboration with the Samsung Advanced Institute of Technology (SAIT). "We've taken advantage of the fact that, on the nanoscale, light can flow around objects like water," said Brongersma, who is a professor of materials science and engineering and senior author of the Oct. 22 Science paper detailing this research. "The field of nanoscale photonics keeps bringing new surprises and now we're starting to impact real technologies. Our designs worked really well for solar cells and now we have a chance to impact next generation displays." In addition to having a record-setting pixel density the new "metaphotonic" OLED displays would also be brighter and have better color accuracy than existing versions, and they'd be much easier and cost-effective to produce as well.
OLED displays were on the mind of Won-Jae Joo, a SAIT scientist, when he visited Stanford from 2016 to 2018. During that time, Joo listened to a presentation by Stanford graduate student Majid Esfandyarpour about an ultrathin solar cell technology he was developing in Brongersma's lab and realized it had applications beyond renewable energy. "Professor Brongersma's research themes were all very academically profound and were like hidden gems for me as an engineer and researcher at Samsung Electronics," said Joo, who is lead author of the Science paper. Joo approached Esfandyarpour after the presentation with his idea, which led to a collaboration between researchers at Stanford, SAI and Hanyang University in Korea. "It was quite exciting to see that a problem that we have already thought about in a different context can have such an important impact on OLED displays," said Esfandyarpour. Samsung had given up trying to pattern side-by-side RGB in large displays in 2015 and left the field to. LG. The crucial innovation behind both the solar panel and the new OLED is a base layer of reflective metal with nanoscale (smaller than microscopic) corrugations, called an optical metasurface. The metasurface can manipulate the reflective properties of light and thereby allow the different colors to resonate in the pixels. These resonances are key to facilitating effective light extraction from the OLEDs. "This is akin to the way musical instruments use acoustic resonances to produce beautiful and easily audible tones," said Brongersma, who conducted this research as part of the Geballe Laboratory for Advanced Materials at Stanford.
In conventional RGB-OLEDs, sub-pixels have different heights. In order to create a flat screen overall, the materials deposited above the emitters have to be laid down in unequal thicknesses. Manufacturers take advantage of these difference using micro-cavities to increase the light output. By contrast, in the proposed OLEDs, the base layer corrugations allow each pixel to be the same height and this facilitates a simpler process for large-scale as well as micro-scale fabrication. In lab tests, the researchers successfully produced miniature proof-of-concept pixels. Compared with color-filtered white-OLEDs (which are used in OLED televisions) these pixels had a higher color purity and a twofold increase in luminescence efficiency -- a measure of how bright the screen is compared to how much energy it uses. They also allow for an ultrahigh pixel density of 10,000 pixels-per-inch. Samsung is trying to implement the solution on a large display, while Brongersma awaits the results, hoping to be among the first people to see the meta-OLED display in action.
Figure 1: 10,000 ppi Using Metaphotonic Technology
