OTI’s cathode materials to be applied to OLED under display camera

Canada-based startup OTI Lumionics’s cathode patterning materials is expected to be applied to organic light emitting diode (OLED) under display camera (UDC) technology next year.

OTI received Series A Plus funding from LG Technology Ventures earlier this year. UDC technology allows cameras to be under the front display of smartphones to achieve a full screen design, instead of having a notch or punch-in-hole.

OTI Lumionics CEO Michael G. Helander told TheElec in an interview that the company’s cathode patterning materials was at the final stages of a review by an unnamed Chinese clients. The materials is expected to be used in smartphones with UDC launching next year, he said.

OLED is electro-luminescent, meaning it emits light on its own. Top emission OLED has the light going through the cathode. Cathode is not transparent but it was attached thinly so there were no problems until now to express the screen. But for UDC, cathode requires patterning to guarantee more transmittance so that the camera can work while having a display surface atop it. 

Earlier this month, Chinese phone maker ZTE launched its Axon 20 5G smartphone that had UDC technology. Compatriot display maker Visionox supplied to the necessary displays. Visionox didn’t use cathode patterning and instead deposited a fine metal mask.

Smartphone and OLED leaders Samsung Electronics and Samsung Display has been developing UDC technology by shooting lasers on the cathode to form the needed patterns. They used open metal mask.

The camera is positioned at the top center, same as punch-in-hole cameras. Samsung Display was the first to supply a hole display OLED, to Samsung Electronics. Samsung launched the Galaxy S10 series back in 2019 that used the holed display.

OTI showcased its cathode patterning materials at Society for Information Display 2020 that can be applied to prior technologies. Previous, cathode electrode materials were needed for UDC.

OTI’s method requires just an additional cathode patterning deposition chamber added to deposition equipment already in use. Fine metal mask is used to deposit the patterns before the cathode is deposited. After these processes are done, cathode, via open metal mask, is deposited to the whole substrate. OTI says the cathode will deposited while avoiding the organic materials. Mg-Ag cathode materials will gather around and form the pattern.

Cathode patterning is expected to be applied not only to smartphone OLED panels but larger OLED panels as well.

Samsung Display’s QD Display uses OLED. LG Display meanwhile has white OLED, in which the direction of the light is opposite to it. White OLED has the light going through the anode rather than the cathode. This is called bottom emission and this method has no cathode transmittance problem.

QD Display uses the top emission method. The light passes through the cathode. Samsung Display plans to use laser to make holes and thereby make a secondary electrolyte. It will than deposit the main cathode thinly. The first commercial version of the display will launch next year.

LG Display’s white OLED can be used for transparent displays. The company last month said it supplied 55-inch transparent OLED for use in China’s subways. When transparent, white OLED uses the top emission method. OTI believes its cathode patterning technology can be used for transparent displays as well.