OTI Lumionics, a leader in the development of advanced materials for OLED displays, recently announced that the latest version of ConducTorr cathode patterning material (CPM) is ready for mass production. It will start shipping to display customers in Q4 2020 for use in next-generation mobile devices with under display camera and face unlock.
With the increasing demand for mobile devices with larger screens and smaller bezels, device manufacturers are looking for innovative solutions to make the display partially transparent. They can move front-facing camera and 3D facial recognition sensors (i.e., face unlock) under the display to eliminate having to make a notch or cut-out in the display.
Elaborating on the latest version of ConducTorr, Michael Helander, CEO of OTI Lumionics said: “We received a lot of positive feedback from our customers in regards to the performance of our ConducTorr CPM materials. However, one consistent pain point that we heard across the board was that our solution required some changes to their manufacturing process, which could slow down adoption in mass production.
“Using our proprietary computational materials design platform, we were able to rapidly incorporate this customer feedback into the next-generation of ConducTorr CPM materials, that are now compatible with all the existing OLED display manufacturing, which makes it easier for our customers to adopt in mass production with minimal changes to their existing manufacturing process.”
Partially transparent displays
It would be interesting to know how the displays are made partially transparent. He said that the displays used in our mobile devices today are already partially transparent due to small gaps between all the various layers that allow a very small amount of light through. You can see this very limited transparency in optical based under display fingerprint sensors.
However, to move the camera and 3D facial recognition (e.g., Face ID) under the display, we need at least an order of magnitude higher transparency. To achieve this high level of transparency, we cut millions of tiny micrometer size holes in the display that fit between all the pixels.
These tiny holes allow more light to pass through the display, making it transparent, but still allows the display to function since the holes are positioned between the pixels. The manufacturing challenge is then making all of these tiny holes in the display without damaging the surrounding pixels, which is where the ConducTorr CPM materials come into play.
That leads to the query: how will the cathode layer work? He added that if you look at a cross-section of the OLED display used in most modern smartphones, it is made up of many different layers of material stacked on top of each other. Most of these layers are actually already transparent (or partially transparent).
However, the cathode layer is a thin layer of metal that covers the entire surface of the display blocking light. The ConducTorr CPM materials allow the cathode layer to patterned with the millions of tiny holes required to make the display transparent enough to move the camera and 3D facial recognition under the display. The holes are created through a self-assembly process, essentially atoms and molecules arranging themselves on the nanoscale using ConducTorr CPM.
Working with mobile device makers
It will be interesting to know about the mobile device makers that OTI has worked with, and in what areas. Helander said: “We work with the top mobile device brands (and their display suppliers) in Korea, China and USA that represent >90 percent of the combined market share. They are covering smartphones, smart watches, tablets, laptops, monitors and TVs. We are expecting the product announcements from our customers starting next year.”
Next, what is being done in the other areas, like transparent displays for AR, high-bright display with longer battery, etc. According to him, the large-area transparent displays are another major area of focus for us. To make a transparent display, you also need to cut millions of tiny holes in the display in between all the pixels.
“If you look at the recently announced Xiaomi transparent OLED TV, which is based on an LG transparent OLED panel, the transparency is only ~33 percent (based on the LG panel spec). The reason the transparency is this low is that the cathode layer is unpatterned, meaning that it actually covers all the millions of tiny holes in the display, absorbing a lot of light. With the ConducTorr CPM, the transparency can easily be increased by 2x or more. We actually demonstrated a transparent display at SID Display Week 2019 with >65 percent transparency in partnership with ITRI in Taiwan.”
Finally, a look at the areas where OTI will be working on next. Helander said: “We believe that rollable and foldable displays will enable exciting new form factors for mobile devices, but that current technology results in displays that have limited flexibility (i.e., large bending radius) and prohibitively high costs.
“To help address these barriers to mass adoption of rollable and foldable displays we are working on a new line of advanced materials that will help make these displays thinner, cheaper and more flexible.”