Researchers at South Korean panel maker LG Display (LGD) pointed out that the company has developed an efficient OLED on Silicon (OLEDoS) and color filter structure.
According to LGD researcher Choi Dong-wook, the thin-film encapsulation material, which protects OLEDs from water and oxygen, can be made 2.5 micrometers thick, enough to prevent light from leaking out and mixing different colors of light.
And LGD developed a method to directly form a 1.5-micron-thick CoE structure (Color filter on Encap) on OLEDoS thin-film encapsulation.
Choi Dong-wook points out that this approach has advantages in viewing angles and preventing color mixing compared to thin-film transistors (TFTs) that are held together with glass substrates and attached to OLEDoS structures.
As for SONY’s OLEDoS method, the color filter of OLEDoS is formed separately first, and then it is combined with OLEDoS.
Choi Dong-wook pointed out that this method will affect the light transmittance, so SONY will use lens technology to improve the brightness.
In addition, in order to form color filters on thin film packages, LGD has also developed a material and process that can form color filters below 100 degrees to protect OLED materials from deteriorating states when exposed to high temperatures.
And SONY’s approach is carried out at 230 degrees, which can not affect the OLED material.
Choi Dong-wook also pointed out that LGD uses atomic layer deposition (Atomic layer deposition) to deposit the first thin film, and then puts silicon nitride on top to achieve 1.5-micron thickness color filters.
LGD is developing OLEDoS that puts red, green, and blue filters on top of white OLEDs, and the company aims to be a follow-on supplier to Apple’s first mixed reality (MR) device in 2023. Since Amoled technology display is generally for large platforms, OLEDoS will be more for small devices.