OLED Capping Layers for Front Brightness and Color Uniformity
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Solution Overview
Problem
Organic light-emitting display apparatuses suffer from insufficient brightness in the front due to light being guided along boundaries in the multilayer structure, and increasing current flow leads to deterioration of the intermediate layer.
Innovation Solution
The use of a substrate with separate pixel electrodes for red, green, and blue light emission layers, along with capping layers of varying refractive indices to enhance light emission and reduce color coordinate variations when viewed from the sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the amount of current flowing through between the pixel electrode and the opposite electrode is increased to increase light emission, then brightness is improved, but the intermediate layer becomes deteriorated
Solution Approach 1:
The patent divides the intermediate layer into multiple sub-layers (first intermediate layer and second intermediate layer) with different materials and functions. The first intermediate layer (hole transport layer) and second intermediate layer (electron transport layer) are segmented to optimize current distribution and reduce deterioration, allowing brighter display without compromising layer durability.
Solution Approach 2:
The patent uses composite material structures in the intermediate layers, combining different organic materials with specific properties. The first intermediate layer uses materials optimized for hole transport while the second intermediate layer uses materials optimized for electron transport, creating a composite structure that enhances overall device performance and durability under high current conditions.
2Adaptability or versatility
If a multilayer structure including pixel electrode, intermediate layer, and opposite layer is used, then device functionality is achieved, but light is guided along boundaries causing insufficient front brightness
Solution Approach 1:
The patent applies local quality by creating specific optical properties at different locations within the device. The intermediate layers are designed with specific refractive indices and thicknesses to locally control light extraction efficiency at the pixel electrode-intermediate layer and intermediate layer-opposite layer interfaces, enhancing front brightness without compromising overall device functionality.
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
This configuration increases brightness in the front while minimizing color variations when viewed from the sides, improving the overall display quality by optimizing light emission and color consistency.
Implementation Method 1
capping layers of varying refractive indices to enhance light emission
Data Source
AI summary
Provided is an organic light-emitting display apparatus, including a substrate, a first pixel electrode, a second pixel electrode, and a third pixel electrode, disposed on the substrate separated from one another, a red emission layer disposed corresponding to the first pixel electrode, a green emission layer disposed corresponding to the second pixel electrode, and a blue emission layer disposed corresponding to the third pixel electrode, an opposite electrode disposed over the red, green, and blue emission layers facing the first to third pixel electrodes, a first capping layer disposed on the opposite electrode corresponding to the first and second pixel electrodes, and a second capping layer disposed on the first capping layer corresponding to the first and second pixel electrodes and disposed on the opposite electrode to correspond to the third pixel electrode.