Organic EL Device Third Layer Electron Injection Control
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Solution Overview
Problem
Organic EL devices with blue light emitting layers formed using vacuum deposition methods often result in inefficient electron injection into red and green light emitting layers, leading to reduced light emitting efficiency and color purity due to the lack of selective light emission from the required layers.
Innovation Solution
Incorporating a third layer composed of an organic material with dispersed electron injection materials between the light emitting layers, formed using a liquid phase process for the first and second layers and a gaseous phase process for the blue light emitting layer, to enhance electron injection and carrier control, allowing for selective light emission from the desired layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a blue light emitting layer is formed using a vacuum deposition method over the entire face including red and green light emitting layers, then the manufacturing process is simplified and productivity is improved, but electron injection into the red and green light emitting layers becomes insufficient and color purity decreases
Solution Approach 1:
The patent divides the light emitting layer into multiple segments: a first light emitting layer (red or green), a third layer (carrier blocking layer) with different properties, and a second light emitting layer (blue). This segmentation allows each layer to perform its specific function, preventing electron leakage into adjacent layers while maintaining efficient manufacturing through vacuum deposition of the entire structure.
Solution Approach 2:
The third layer acts as an intermediary carrier blocking layer positioned between the first and second light emitting layers. This intermediate layer has different electron injection properties that prevent electrons from the blue light emitting layer from injecting into the red or green light emitting layers, thereby maintaining color purity while allowing the simplified vacuum deposition process to continue.
2Duration of action of moving object
If a blue light emitting layer is formed using a vacuum deposition method, then the light emitting life is extended to a practical level, but electron injection into red and green light emitting layers is insufficient leading to reduced light emitting efficiency
Solution Approach 1:
The patent segments the light emitting structure into distinct functional layers with the third layer specifically designed to control electron injection. This segmentation ensures that electrons are efficiently injected into the blue light emitting layer (maintaining long light emitting life) while being blocked from injecting into the red or green light emitting layers (preventing energy loss and maintaining efficiency).
Solution Approach 2:
The third layer introduces local quality differentiation within the light emitting structure. This layer has specific electron injection blocking properties that are localized at the interface between the blue and red/green light emitting layers, allowing efficient electron injection where needed (in the blue layer) while preventing it where harmful (in the red/green layers).
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 improves light emitting efficiency and color purity by stabilizing carrier control and reducing electron injection material agglomeration, enabling the organic EL device to selectively emit light from the required layers, thus enhancing the overall performance of the device.
Implementation Method 1
electrons are not sufficiently injected into the red light emitting layer and the green light emitting layer from the blue light emitting layer
Implementation Method 2
the first layer and a third layer are formed using a liquid phase process
Implementation Method 3
a blue light emitting layer is formed by a vacuum deposition method (deposition method)
Implementation Method 4
the third layer is composed of an organic material in which an electron injection material is dispersed
Data Source
AI summary
An organic EL device includes light emitting functional layers as a first layer with a function of emitting light of a first color which are provided between anodes and a cathode, a light emitting functional layer as a second layer with a function of emitting light of a second color, first light emitting elements that include an intermediate layer as a third layer which is provided between the light emitting functional layers and that emits light of the first color, and a second light emitting element that includes the light emitting functional layer that is provided between the anode and the common cathode, wherein the light emitting functional layers and the intermediate layer are formed using a liquid phase process, the light emitting functional layer is formed using a gaseous phase process, and the intermediate layer is composed of an organic material in which an electron injection material is dispersed.