Organic EL Device Vertical Conductive Stacking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic electroluminescent devices, the second electrode layer's electrical resistance variation leads to luminescent variation, especially in top emission-type devices, where the thin second electrode layer requires auxiliary wires to reduce connection resistance, increasing the substrate size due to the need for a larger contact area between auxiliary wires and conductive patterns.
Innovation Solution
An organic EL device with a first conductive pattern at the lower layer side and a second conductive pattern with lower sheet resistance at the upper layer side, connected through a third conductive pattern on the insulating film, allowing potential application to the second electrode layer without increasing the contact area, and optionally using auxiliary wires to connect the second electrode layer directly or indirectly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary wires are formed to reduce connection resistance of the second electrode layer, then luminescent variation is prevented, but the peripheral region width and substrate size increase
Solution Approach 1:
The patent transitions from a planar contact structure to a three-dimensional stacked structure by forming the upper layer conductive pattern on top of the lower layer conductive pattern at the contact portion. This vertical stacking enables electrical connection without requiring a larger lateral contact area, thus preventing substrate size increase while maintaining luminescent uniformity.
Solution Approach 2:
The patent embeds the lower layer conductive pattern within the contact portion structure, with the upper layer conductive pattern positioned on top. This nested configuration allows both conductive patterns to occupy the same lateral space, reducing the required peripheral region width while ensuring reliable electrical connection for the auxiliary wires.
2Reliability
If the overlapped area between auxiliary wire and lower layer-side conductive pattern is increased to reduce connection resistance, then connection resistance decreases, but the contact portion width must be increased
Solution Approach 1:
The patent increases the overlapped area by stacking the conductive patterns vertically rather than expanding them laterally. The upper layer conductive pattern is formed on top of the lower layer conductive pattern at the contact portion, creating a three-dimensional overlap that reduces connection resistance without increasing contact portion width.
3Illumination intensity
If the second electrode layer thickness is reduced to improve light transparency, then light emission efficiency improves, but electrical resistance increases causing luminescent variation
Solution Approach 1:
The patent creates a composite conductive structure by stacking two conductive patterns with different materials or properties. The lower layer conductive pattern and upper layer conductive pattern work together to provide both low electrical resistance and good light transparency, combining the advantages of different conductive materials in a layered configuration.
Solution Approach 2:
The upper layer conductive pattern acts as an intermediary between the auxiliary wires and the thin second electrode layer. It provides a low-resistance electrical connection path while allowing the second electrode layer to remain thin for optimal light transparency, mediating between the conflicting requirements of electrical conductivity and optical transparency.
Data Source
AI summary
An organic electroluminescent device includes a pixel region in which a plurality of pixels is disposed on a support substrate, each pixel having an electroluminescent element in which at least a first electrode layer, a light-emitting layer, and a second electrode layer are laminated in that order at an upper layer side of an insulating film; a first conductive pattern portion provided at a lower layer side of the insulating film for applying a potential to the second electrode layer; and a second conductive pattern portion which is composed of a conductive film having a sheet resistance lower than that of the second electrode layer and which is provided at the upper layer side of the insulating film to connect the second electrode layer to the first conductive pattern portion. In this organic EL device, the second conductive pattern portion has a third conductive pattern portion which is provided on an upper surface of the first conductive pattern portion at a contact portion composed of a non-forming region of the insulating film and which is in contact with the first pattern portion.