LG Display has developed an OLED on Silicon and color filter structure with high efficiency, a company researcher said.
The thin film encapsulant, which protects OLED from water and oxygen, is made 2.5 micrometers thick, which is enough for the light not to leak out and prevents different colors of light from mixing, LG Display research Choi Dong-wook said at a conference held in South Korea.
LG Display then developed a method to form a 1.5-micrometer thick color filter directly on top of the encapsulant, called Color filter on Encap, or CoE.
The method has an advantage in viewing angle and color protection compared to having a glass substrate as a color filter on top and a glass substrate as a thin-film transistor on the bottom and attaching the two to the OLEDoS.
The latter method is used by Sony and can affect the aperture ratio. Choi said the Japanese tech giant applies lenses to increase the brightness.
LG Display used color filter materials and processes that can help it form at 100 Celsius to protect the OLED material.
Sony’s method can use up to 230 Celsius without affecting the OLED material.
Meanwhile, LG Display also used atomic layer deposition to lay the first layer of the thin film, then put silicon nitride on top, to achieve the 1.5-micrometer thickness of the color filter, Choi said.
LG Display is developing OLEDoS that lays the red, green and blue color filter on top of a white-OLED.
The company is aiming to supply them to Apple’s follow-up to its first mix realty device in 2023.