OLED Pixel Definition Layer Thickness Uniformity
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Solution Overview
Problem
The existing organic light emitting diode (OLED) displays face limitations in reducing the thickness of the pixel definition layer and achieving uniformity due to material and process characteristics, leading to protrusions and depressions at the bottom of the organic emission layer during the laser induced thermal imaging method, which deteriorates transfer quality.
Innovation Solution
The OLED display incorporates a pixel definition layer with alternating inorganic and organic patterns of different thicknesses and directions, where the inorganic pattern is formed with materials like silicon oxide or silicon nitride and the organic pattern with polyimide, minimizing protrusions and depressions by optimizing the layer thickness and formation sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the pixel definition layer is formed with an organic layer to partition pixel areas, then the pixel definition layer can be formed with material flexibility, but the thickness cannot be reduced and uniformity of height cannot be achieved due to material characteristics
Solution Approach 1:
The pixel definition layer is formed as a composite structure comprising both organic material layers (for flexibility and patterning) and inorganic material layers (for thickness control and uniformity). This composite approach allows the organic layer to provide material adaptability while the inorganic layer compensates for thickness non-uniformity, resolving the contradiction between material flexibility and manufacturing precision.
2Productivity
If the donor film is disposed on the substrate and laser beams are irradiated to transfer the organic emission layer, then the transfer process can be performed, but large curves are generated near the pixel definition layer, deteriorating transfer quality
Solution Approach 1:
The pixel definition layer is designed with locally differentiated properties, where the inorganic layer thickness is specifically increased at regions adjacent to the pixel definition layer. This local thickening creates a buffer zone that prevents the transfer layer from forming large curves during laser irradiation, thereby maintaining high transfer quality while preserving the efficiency of the laser-induced thermal imaging transfer process.
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 transfer quality of the organic emission layer by reducing bottom protrusions and depressions, improving pattern quality and providing sufficient expansion space for the transfer process, thereby increasing the overall quality of the OLED display.
Implementation Method 1
The laser induced thermal imaging method includes providing a base film and a donor film including a light-to-heat conversion layer and a transfer layer, and irradiating laser beams to the donor film to partially expand the light-to-heat conversion layer and expand the adjacent transfer layer thereby transferring the transfer layer onto a substrate
Data Source
AI summary
An organic light emitting diode (OLED) display includes: pixel electrodes formed on a substrate; a pixel definition layer between the pixel electrodes and partitioning a pixel area; organic emission layers of a plurality of colors on the pixel electrodes; and a common electrode on the organic emission layers. The pixel definition layer includes a first pattern and a second pattern having different formation materials, thicknesses, and extension directions.