OLEDON Chief executive Hwang Guang-hoon said on May 27 that he received mostly positive reviews at SID 2019.
“We had a lot of good feedback,” said the CEO of the South Korean manufacturer, adding that such upbeat views are rare at the event.
The response was to the company's announcement that it can achieve up to 10,000 pixels per inch (PPI) by using vertical plane evaporation source method instead of the existing inline evaporation process to minimize the shadowing effect.
Hwang, who founded OLED three years ago, also noted that Samsung Display is showing keen interest in its latest technology.
Shadowing effect indicates unintended excessive shadowing due to high-incident angle incident molecules relative to the normal angle, which are prevented from reaching the substrate.
Currently, the maximum PPI for mass produced OLED displays is under 600. It’s hard to get past that threshold is because it’s not easy avoiding shadowing when you have more holes in the fine metal mask (FMM).
Pixels in OLED panels are created by depositing organic materials through tiny holes into the FMM. The closer together the holes, the higher the PPI. But this also means the FMM had to be thinner because the shadowing effect gets worse due to the aspect ratio.
OLEDON says its vertical plane evaporation technology has solved the problem.
“The vaporized organic material is transported in a linear fashion, meaning that the FMM can be thicker to prevent excessive shadowing,” said Hwang.
As evidence, the CEO presented data on shadowing, which didn’t occur while producing a higher PPI under the vertical plane evaporation method.
When the organic materials are deposited through 1000 PPI masks, a PPI of up to 10,000 was achieved.
“With plane evaporation, we can improve the PPI for small and mid-sized OLED panels,” said the CEO. “We can also use it for ultra-large panels for 12th generation production lines without causing the substrate to sag under the FMM weight.”
Currently, only the 10.5th generation lines produce substrate for the largest mass-produced displays.
Vertical plane evaporation also makes it possible to enhance the efficiency of organic materials while controlling the mixing ratio between the host and dopant. Dopant is what emits the light in the panel, while the host is increases the efficiency of the light. Light efficiency usually depends on this ratio.
Vertical plant evaporation is utilized through a metallic belt.
Organic materials are first deposited in the inline method underneath the belt. The belt is then removed. Then heat is applied from under the substrate to the organic material on the belt. The donor film on the belt doesn’t spread because it doesn’t pass through a nozzle. It also moves in a direct line to the board.
“We found that results were better when using a curved plane source on the belt,” said Hwang.