OELD Second Electrode Calcium Oxide Diffusion Barrier
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Solution Overview
Problem
Organic electroluminescent display devices face issues with moisture absorption and calcium diffusion, leading to reduced lifespan and display quality due to poor adhesion between calcium and aluminum layers, and foreign substances causing short-circuits during the formation of the organic light emitting layer.
Innovation Solution
A dual panel type OELD device is manufactured with a second electrode having a triple-layered structure, including a calcium-diffusion-preventing layer, a low resistance material, and a moisture-absorbing material, and a calcium oxide layer is formed on the second electrode to prevent diffusion and enhance adhesion, along with a patterned spacer to maintain electrical connection and cell gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a calcium layer is used as moisture absorbent, then moisture absorption function is improved, but calcium diffuses into aluminum layer causing reduced adhesion and device lifespan
Solution Approach 1:
An aluminum oxide layer is introduced as an intermediary barrier between the calcium layer and aluminum layer. This oxide layer prevents calcium atoms from diffusing into the aluminum layer while allowing the calcium layer to maintain its moisture absorption function, thus resolving the contradiction between moisture absorption and device reliability
Solution Approach 2:
The second electrode is designed as a composite structure with multiple layers including calcium, aluminum, and aluminum oxide. This composite structure combines the moisture absorption capability of calcium with the diffusion barrier properties of aluminum oxide, achieving both improved moisture absorption and maintained device lifespan
2Ease of manufacture
If foreign substances are present during organic light emitting layer formation, then manufacturing complexity is reduced, but short-circuits occur between electrodes
Solution Approach 1:
The aluminum oxide layer is formed beforehand on the aluminum layer to create a protective barrier. This pre-formed barrier prevents foreign substances from causing short-circuits during the organic light emitting layer formation process, maintaining both manufacturing simplicity and electrical connection reliability
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 prevents calcium diffusion, absorbs moisture, and reduces short-circuits, thereby improving the lifespan and display quality of the OELD device while maintaining efficient electrical connection.
Implementation Method 1
forming a calcium oxide layer on the second electrode to prevent diffusion and enhance adhesion
Implementation Method 2
forming a moisture-absorbing layer on the calcium oxide layer
Data Source
AI summary
A method of manufacturing an organic electroluminescent display device includes forming a first electrode on a first substrate including a plurality of pixel regions; forming a patterned spacer on the first electrode in the pixel region; forming an organic light emitting layer on the first electrode in the pixel region and on the patterned spacer; forming a second electrode on the organic light emitting layer; forming a calcium oxide layer on the second electrode; forming a moisture-absorbing layer on the calcium oxide layer; forming a driving thin film transistor on a second substrate; and forming a connection electrode connected to the driving thin film transistor, the connection electrode contacting the second electrode on the patterned spacer.