OLED Subpixel Hole Transporting Layer Protection
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Solution Overview
Problem
The challenge in manufacturing large-area organic light emitting display devices is the sagging of deposition masks, which limits the reduction of pixel size and hinders the application of ultra-high resolution, leading to deterioration of element characteristics and increased defect rates.
Innovation Solution
A display device design featuring a substrate with subpixels, electrodes, and an organic light emitting layer with a first hole transporting layer that includes a sub hole transporting layer to cover the light emitting layer, preventing damage from exposure and solution processes, and using common layers for the second hole transporting layer and hole injecting layer to reduce manufacturing processes and defect rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If FMM technology is used to form organic light emitting layer, then small-to-medium panel can be manufactured, but large area application is difficult due to mask sagging
Solution Approach 1:
The patent divides the hole transporting layer into multiple sub-layers (first sub hole transporting layer and second sub hole transporting layer) with different functions. The first sub layer protects the light emitting layer during manufacturing, while the second sub layer provides hole transporting function, resolving the contradiction between large area manufacturing and precision control.
2Measurement precision
If pixel size is reduced for ultra-high resolution, then resolution is improved, but mask sagging problem worsens in large area panels
Solution Approach 1:
The first sub hole transporting layer is formed before the light emitting layer deposition is completed, creating a protective structure in advance. This preliminary action prevents mask sagging from affecting the light emitting layer quality, enabling ultra-high resolution in large area panels.
3Ease of manufacture
If light emitting layer is exposed to solution process, then manufacturing is simplified, but element characteristics are deteriorated
Solution Approach 1:
The first sub hole transporting layer acts as an intermediary protective barrier between the light emitting layer and the solution process. It allows the solution process to proceed for manufacturing simplicity while preventing direct contact that would deteriorate element characteristics.
4Reliability
If multiple separate layers are used for hole transporting and hole injecting, then functionality is optimized, but manufacturing complexity increases
Solution Approach 1:
The patent merges the hole transporting function and hole injecting function into a single integrated hole transporting layer structure with sub-layers. This combining reduces manufacturing complexity while maintaining optimized functionality through the differentiated sub-layer design.
Data Source
AI summary
A display device comprises a substrate provided with a first subpixel and a second subpixel adjacent to the first subpixel, a first electrode provided on the substrate, including a first sub electrode provided on the first subpixel and a second sub electrode provided on the second subpixel, an organic light emitting layer including a first organic light emitting layer arranged on the first sub electrode and a second organic light emitting layer arranged on the second sub electrode, a second electrode arranged on the organic light emitting layer, and a first bank provided between the first sub electrode and the second sub electrode, partitioning the first subpixel from the second subpixel, wherein the first organic light emitting layer includes a light emitting layer and a first hole transporting layer arranged on the light emitting layer, the first hole transporting layer includes a first sub hole transporting layer and a second sub hole transporting layer, and the first sub hole transporting layer of the first hole transporting layer covers the light emitting layer between the light emitting layer and the second sub hole transporting layer. Therefore, as the first sub hole transporting layer is provided to cover the light emitting layer of the organic light emitting layer, the organic light emitting layer may be prevented from being damaged by an exposure process or a solution process, whereby a defect rate of the complete display device may be reduced.