Foldable OLED firms replacing polarizer with color filters 

Color filters will replace polarizers in foldable organic light emitting diode (OLED) panels in the future, a South Korean research firm said on Friday.

Major panel companies were working on such technology as color filters will allow the panels to become thinner and more brighter, UBI Research said.

Polarizers in OLED panels are used to deflect reflection from external lights. 

The current iteration of foldable OLED panels stacks a touch on encapsulation layer, polarizer, optical clear adhesive, cover window atop the light emitting layer. It uses polyimide films or ultra thin glasses for the cover window, depending on the vendor.

Panel companies were already applying polarizers that are in the 10 micrometer range in terns of thickness from the previous 100 micrometer ones to increase the flexibility of the panels, UBI Research said. However, this thinner polarziers are still considered thick and lowers the brightness of the OLED panels, it said.

In 2017, Chinese display giant BOE showed off a 5.46-inch WQHD foldable OLED panel that used a lower temperature color filter instead of polarizer at the Society of Information Display (SID) 2017 tradeshow.

The company at the time said the display was 100 thinner and 23% more bright than OLED panels that used polarizers. The panel also reflected light less and consumed 20% less power, BOE said at the time.

Samsung Display was researching the same technology and will likely apply it commercially two to three years from now, UBI Research said.

Meanwhile, the research firm was skeptical of other methods that were being tested to make foldable OLED panels thinner. There is currently two layers of polyimide films stacked at the bottom of the panel and there are attempts to change this to one layer. However, UBI Research said substrate with one layer of polyimide film was more difficult to handle and may be damaged during the laser lift off  process __ this is when a polyimide film is cut off via laser from a carrier glass. 

Another attempt to make OLED panels thinner is to make the inorganic and organic materials used to make the thin film encapsulation thinner. Currently, the inorganic materials are 1 micrometer thick while the organic ones are between 4 micrometers to 8 micrometers. But making the organic materials thinner will increase the signal to noise ratio of the touch sensor from the thin film transistor signals, UBI Research said.