OLED Arched Optical Coupling Layer for Light Extraction
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Solution Overview
Problem
The existing OLED array substrates suffer from lowered light extraction efficiency due to total reflection inside the uniform-thickness type optical coupling layer, which attenuates light emission and affects the color and density of emitted light when viewed from different angles.
Innovation Solution
An OLED array substrate with an arched top optical coupling layer, where the optical coupling layer has a thickness of λ/4n, with λ being the wavelength of light emitted and n being the refractive index, is designed to reduce total reflection by allowing refraction instead of total internal reflection, and the thickness can vary for pixel units of different colors to optimize light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a uniform-thickness optical coupling layer with high refractive index is used, then the microcavity effect is attenuated and transmittance increases, but total reflection occurs inside the layer causing light intensity loss and reduced light extraction efficiency
Solution Approach 1:
The optical coupling layer transitions from uniform thickness to having different thicknesses in different regions. The central region has a first thickness while the peripheral region has a second thickness that is different from the first. This local variation in thickness allows different parts of the layer to serve different optical functions, reducing total reflection while maintaining the high refractive index benefit for attenuating microcavity effect.
Solution Approach 2:
The thickness parameter of the optical coupling layer is changed from a constant value to a spatially varying parameter. By adjusting the thickness distribution (first thickness in central region, second thickness in peripheral region), the optical properties of the layer are optimized to reduce total internal reflection and improve light extraction efficiency without sacrificing the microcavity attenuation benefit.
2Reliability
If the optical coupling layer has high refractive index to attenuate microcavity effect, then transmittance of cathode increases, but total reflection inside the layer lowers light extraction efficiency
Solution Approach 1:
The optical coupling layer is designed with non-uniform thickness where the central region and peripheral region have different thicknesses. This local quality variation allows the layer to simultaneously achieve microcavity effect attenuation (through high refractive index) and reduced total reflection (through optimized thickness distribution), resolving the contradiction between these two optical performance requirements.
Solution Approach 2:
The optical coupling layer adopts a curved thickness profile rather than a flat uniform structure. The central region has one thickness and the peripheral region has another, creating a gradient or stepped thickness distribution that optimizes light extraction while maintaining microcavity attenuation, effectively using curvature to resolve the optical performance contradiction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The arched top optical coupling layer enhances light extraction efficiency by minimizing total reflection and maximizing transmittance, resulting in improved light emission uniformity and color consistency across different viewing angles.
Implementation Method 1
material for forming the optical coupling layer 5 has a refractive index larger than that of material for forming the cathode 4
Implementation Method 2
total reflection inside the uniform-thickness type optical coupling layer 5
Data Source
AI summary
The present invention provides an OLED array substrate, a manufacturing method thereof, an OLED display panel and an OLED display device. The OLED array substrate comprises a substrate and a plurality of pixel units provided thereon, each pixel unit comprising a TFT, and a first electrode, an organic light-emitting layer, a second electrode and an optical coupling layer sequentially arranged on the TFT, wherein the optical coupling layer comprises a bottom contacting with the second electrode and an arched top protruding towards a light-exiting direction. By forming the optical coupling layer of each pixel unit on the OLED array substrate to be the arched top optical coupling layer, the OLED array substrate, the manufacturing method thereof, the OLED display panel and the OLED display device of the present invention attenuates total reflection of light inside the optical coupling layer, thereby improving light extraction efficiency.