OLED Counter Electrode Roll-Up via Tensile Stress for Short Prevention
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Solution Overview
Problem
The manufacturing of OLED devices is costly and labor-intensive due to the need for multiple mask processes and the risk of electrode shorts, which requires high geometric accuracy and frequent cleaning of shadow masks, leading to a high failure ratio.
Innovation Solution
An OLED device with a substrate electrode, an electroluminescent layer stack, a counter electrode, and a short prevention layer, where a cut is introduced to electrically disconnect the counter electrode from the substrate electrode, and an electrically isolating layer is used to weaken the adhesion of the counter electrode to the electroluminescent layer stack, inducing tensile stress to roll-up the counter electrode and prevent shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple shadow masks are used for depositing different layers, then the geometric accuracy and electrical isolation of electrodes are improved, but the manufacturing cost and process complexity increase significantly
Solution Approach 1:
The patent combines the deposition of counter electrode and short prevention layer into a single shadow mask process. The shadow mask is designed with multiple deposition areas including a first area for the counter electrode and a second area for the short prevention layer, eliminating the need for separate mask processes and reducing overall device complexity
Solution Approach 2:
The shadow mask is segmented into different deposition areas (first area for counter electrode, second area for short prevention layer) with different geometries. This segmentation allows each layer to be deposited with appropriate geometric accuracy while using a single mask, resolving the contradiction between precision and complexity
2Manufacturing precision
If shadow masks are used for deposition processes, then the geometric accuracy of layer deposition is improved, but the manufacturing cost increases due to mask manufacturing and cleaning requirements
Solution Approach 1:
Multiple layer depositions (counter electrode and short prevention layer) are combined into a single shadow mask process, reducing the total number of masks required from multiple to one. This significantly reduces mask manufacturing costs and cleaning requirements while maintaining geometric accuracy through the segmented mask design
3Reliability
If the counter electrode fully covers the electroluminescent layer stack, then the electrical connection and voltage application are improved, but the risk of electrode shorts increases
Solution Approach 1:
The shadow mask is segmented into a first area for counter electrode deposition and a second area for short prevention layer deposition. This segmentation ensures the counter electrode fully covers the electroluminescent layer stack for reliable electrical connection, while the short prevention layer is deposited in specific areas to prevent electrode shorts
Solution Approach 2:
The short prevention layer acts as an intermediary layer between the counter electrode and the substrate electrode. It is deposited in the second area of the shadow mask and prevents direct electrical contact between the counter electrode and substrate electrode, eliminating the harmful short circuit effect while allowing the counter electrode to maintain full coverage
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 method allows for the production of OLED devices with reduced manufacturing effort and increased reliability by using a single shadow mask for the electroluminescent layer stack, preventing electrode shorts and reducing the risk of leakage currents, thereby enhancing the operational stability and longevity of the devices.
Implementation Method 1
A tensile stress is induced in the double layer by the short prevention layer which is suitable to roll-up the double layer after deposition of the electrically isolating layer
Implementation Method 2
the electrically isolating layer at least partly covers the area of the double layer with the introduced cut to partly dissolve the electroluminescent layer stack at the cut, weakening the adhesion of the double layer to the electroluminescent layer stack adjacent to the cut
Data Source
AI summary
This invention relates to an organic electroluminescent device (1) produced with less effort comprising a substrate (2), a substrate electrode (3) on top of the substrate (2), an electroluminescent layer stack (4) with at least one organic light emitting layer on top of the substrate electrode (3), a counter electrode (5) at least covering the electroluminescent layer stack (4), and a short prevention layer (6) covering the counter electrode (5) establishing a double layer (DL) of counter electrode (5) and short prevention layer (6), and an electrically isolating layer at least partly on top of the short prevention layer, where a tensile stress (TS) is induced to the double layer (DL) by the short prevention layer (5) suitable to roll-up (10) the double layer (DL) after deposition of the electrically isolating layer (8) adjacent to a cut introduced at least to the double layer (DL) in an area, where the double layer (DL) is arranged on top of the electroluminescent layer stack (4) suitable to electrically disconnect the counter electrode (5) from the substrate electrode (3), where the electrically isolating layer (8) at least partly covers the area of the double layer with introduced cut (7) to partly dissolve the electroluminescent layer stack (4) to weaken the adhesion of the double layer to the electroluminescent layer stack adjacent to the cut to roll-up the double layer in the vicinity of the cut. The invention further relates to a method of manufacturing such an OLED device.