Display Panel Intermediate Layers for Impurity Blocking
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Solution Overview
Problem
Self-luminous elements, such as organic electroluminescence (EL) elements, face issues with deterioration due to impurities like water and oxygen, leading to decreased luminance efficiency and shortened emission life, primarily because low work function alkali metals and alkaline earth metals used in functional layers react easily with these impurities.
Innovation Solution
A display panel structure is developed with a fluoride of a first metal as the first intermediate layer to block impurities, and a rare earth metal as the second intermediate layer to improve electron injection and stability, preventing deterioration and enhancing luminance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a functional layer containing low work function alkali metal or alkaline earth metal is used to improve electron injection, then electron injection property is improved, but the functional layer deteriorates due to reaction with impurities such as water and oxygen, causing decreased luminance efficiency and shortened emission life
Solution Approach 1:
An inorganic barrier layer is introduced as an intermediary between the light-emitting layer and the functional layer containing alkali/alkaline earth metals. This barrier layer prevents impurities (water and oxygen) from reaching and reacting with the metal-containing functional layer, thereby protecting it from deterioration while allowing the functional layer to maintain its electron injection function.
Solution Approach 2:
The inorganic barrier layer creates a protected environment that isolates the reactive alkali/alkaline earth metals from harmful impurities. By blocking the diffusion of water and oxygen molecules, the barrier layer effectively creates an inert environment for the functional layer, preventing oxidation and degradation reactions.
2Stability of the object's composition
If an inorganic barrier layer is provided to prevent functional layer deterioration from impurities, then storage stability is improved, but light extraction efficiency may be affected
Solution Approach 1:
The thickness of the inorganic barrier layer is precisely controlled within a specific range (0.1 nm to 5 nm). By optimizing this parameter, the layer provides sufficient barrier function to block impurities while remaining thin enough to allow light transmission, thus balancing protection functionality with light extraction efficiency.
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 solution effectively suppresses cathode and electron injection layer deterioration, improves electron injection to the light-emitting layers, and maintains high luminance efficiency and stability over time by blocking impurities and reducing oxidation of the second intermediate layer.
Implementation Method 1
a first intermediate layer disposed on or above the light-emitting layers, the first intermediate layer including a fluoride of a first metal or a complex of the first metal... deterioration of the cathode and an electron injection layer can be suppressed by the first intermediate layer
Implementation Method 2
reduction of the first metal in the first intermediate layer can improve electron injection from the cathode to the light-emitting layers
Implementation Method 3
reduction of the first metal in the first intermediate layer
Implementation Method 4
The second intermediate layer includes a second metal... rare earth metals... suppressing deterioration of the second intermediate layer itself
Data Source
AI summary
A display panel including a substrate, anodes disposed on or above the substrate, light-emitting layers disposed on or above the anodes, a first intermediate layer disposed on or above the light-emitting layers, a second intermediate layer disposed on the first intermediate layer, and a cathode disposed on or above the second intermediate layer. The first intermediate layer includes a fluoride of a first metal or a complex of the first metal. The second intermediate layer includes a second metal. The anodes are light-transmissive and the cathode is light-reflective, or the anodes are light-reflective and the cathode is light-transmissive. The first metal is selected from a group consisting of alkali metals and alkaline earth metals. The second metal is selected from rare earth metals.