Flat Layer Planarization for OLED Electrode Formation
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Solution Overview
Problem
Conventional full-color active matrix organic electroluminescent devices face issues with surface roughness and thermal decomposition of color filters due to high-temperature deposition processes, leading to current leakage and reduced luminance efficiency.
Innovation Solution
A planarization layer is introduced between the color filter and electrode layers, formed using a low-temperature thin film process to create a smooth surface for the electrode, preventing damage to the color filters and improving surface roughness to less than 10 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-temperature thin film process (above 400°C) is used to form the ITO electrode directly on the color filter, then the electrode can be formed with good electrical properties, but the color filter will thermally expand or decompose due to high temperature, resulting in damage and surface roughness
Solution Approach 1:
A flat layer is introduced as an intermediary layer between the color filter layer and the ITO electrode layer. This flat layer serves as a buffer that can withstand the high-temperature deposition process while protecting the color filter from thermal damage. The flat layer is formed by a low-temperature process and provides a smooth surface for subsequent electrode formation, thereby resolving the contradiction between electrode quality and color filter protection.
2Productivity
If the ITO electrode is directly deposited on the rough color filter surface (surface roughness around 20 nm), then the electrode can be formed quickly, but the resulting surface roughness remains high (around 20 nm), causing current leakage and point discharge that reduce luminance efficiency and product life
Solution Approach 1:
The flat layer acts as an intermediary that smooths the surface between the rough color filter and the ITO electrode. By forming this intermediate flat layer first, the subsequent ITO electrode deposition occurs on a smooth surface (surface roughness less than 10 nm), preventing current leakage and point discharge while maintaining formation efficiency.
Solution Approach 2:
The flat layer is formed in advance before the ITO electrode deposition. This preliminary action creates a smooth surface foundation that prevents subsequent problems with current leakage and point discharge, thereby improving luminance efficiency and product life without sacrificing productivity.
3Ease of manufacture
If no flat layer is introduced and the process is simplified, then manufacturing is faster and cheaper, but surface roughness cannot be reduced below 20 nm, leading to current leakage and reduced device reliability
Solution Approach 1:
The flat layer serves as a simple yet effective intermediary that addresses the surface roughness problem. Although it adds one more layer, the flat layer can be formed by a low-temperature process that is relatively simple and efficient, providing a smooth surface (less than 10 nm roughness) that prevents current leakage and improves device 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
This approach enhances the reliability and luminance efficiency of full-color active matrix organic electroluminescent devices by preventing surface damage and current leakage, while extending their lifespan.
Implementation Method 1
a flat layer, which can be formed by a low temperature thin film process and have a surface roughness of less than 10 nm
Data Source
AI summary
A full-color active matrix organic electroluminescent device and fabrication method thereof. The full-color active matrix organic electroluminescent device includes a substrate with a plurality of TFTs, a buffer layer formed on the substrate beyond the TFTs, a color filter formed on the buffer layer, a flat layer formed on the entire surface of the color filter, a first electrode formed on the flat layer, an organic electroluminescent layer formed on the first electrode, and a second electrode formed on the organic electroluminescent layer, wherein the flat layer is formed by a low temperature thin film process.