OLED Electrical Connection via Laser Ablation
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Solution Overview
Problem
Active matrix OLED displays face challenges with low aperture ratio due to opaque circuitry in bottom emitting configurations and high sheet resistance in top emitting configurations, leading to reduced brightness uniformity, increased power consumption, and shortened device lifetime.
Innovation Solution
A method involving a substrate with a conductive bus line and organic electroluminescent media, where a laser is used to ablate the media over the bus line, creating an opening for forming a second electrode, thereby establishing an electrical connection with low resistance, allowing for improved conductivity and reduced laser energy requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bottom emitting configuration is used with opaque circuitry, then aperture ratio is reduced, but manufacturing complexity is simplified
Solution Approach 1:
The patent inverts the conventional bottom-emitting configuration by making the top electrode transparent instead of the bottom electrode. This allows the opaque circuitry to remain at the bottom while light exits through the transparent top electrode, thereby maintaining high aperture ratio without simplifying the circuit configuration.
Solution Approach 2:
The patent transitions from a bottom-emitting to a top-emitting configuration, changing the dimension of light emission. This allows the circuitry to remain in the bottom plane while light exits through the top surface, resolving the conflict between aperture ratio and circuit complexity.
2Area of stationary object
If top emitting configuration is used with transparent electrode, then aperture ratio is improved, but sheet resistance increases
Solution Approach 1:
The patent employs a composite electrode structure combining transparent conductive oxide (TCO) layer with a metal layer. The TCO provides transparency while the metal layer provides low resistance, creating a composite material that achieves both high aperture ratio and low sheet resistance simultaneously.
Solution Approach 2:
The patent changes the electrical parameters of the top electrode by combining materials with different conductivities. The TCO layer provides transparency while the underlying metal layer compensates for the high resistance, achieving optimal balance between optical and electrical properties.
3Manufacturing precision
If laser ablation is used to create opening, then manufacturing precision is improved, but energy consumption increases
Solution Approach 1:
The patent performs preliminary action by forming the conductive bus line with optimized geometry and material composition before laser ablation. This preliminary structuring of the bus line enhances laser absorption and facilitates more efficient ablation with lower energy requirements.
Solution Approach 2:
The patent changes the physical parameters of the bus line (material composition, geometry, thickness) to optimize laser absorption. By adjusting these parameters, the bus line absorbs laser energy more efficiently, reducing the total energy required for precise opening formation.
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 aperture ratio, reduces power consumption, and extends the device's operational lifetime by enabling efficient electrical connections with lower energy input and faster manufacturing processes.
Implementation Method 1
A laser operating at a wavelength and scanned over the conductive bus line in a predetermined direction so that the conductive bus line absorbs sufficient energy to cause the ablation a portion of the organic electroluminescent media over the conductive bus line
Implementation Method 2
the conductive bus line absorbs sufficient energy to cause the ablation
Data Source
AI summary
In one aspect of the present invention, a method of making an OLED device comprises providing a substrate; a first electrode, a conductive bus line over the substrate and an organic electroluminescent media over the first electrode and over the conductive bus line. A laser that operating at a predetermined wavelength and is scanned over the conductive bus line in a predetermined direction so that the conductive bus line absorbs sufficient energy to cause the ablation a portion of the organic electroluminescent media over the conductive bus line thereby forming an opening in the organic electroluminescent media. The width of the laser beam in the predetermined direction is less than four times the width of the conductive bus line; and forming a second electrode over the organic electroluminescent media, the first electrode, and through the opening in the organic electroluminescent media.