OLED Compact Contact Design with Self-Aligned Insulators
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Solution Overview
Problem
Conventional OLED designs often suffer from non-uniform emission due to the close proximity of electrode contacts, leading to localized high electric fields and 'hot spots', which result in uneven light distribution across the panel.
Innovation Solution
The design incorporates a compact contact arrangement where the shortest lateral current path through the active region is longer than the shortest lateral electric field line, with a bus line and insulator layer strategically placed to distribute current uniformly, and the use of patterned electrodes to increase the current travel distance while maintaining low resistive loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If electrode contacts are placed close together to reduce device size, then device compactness is improved, but emission uniformity deteriorates due to localized high electric fields and hot spots
Solution Approach 1:
The patent introduces a bus line structure that extends into the active region, creating a three-dimensional current distribution pathway. This allows current to travel laterally through the bus line before reaching the contact, effectively increasing the current path length without increasing the planar footprint of the device. The bus line acts as an intermediate conductive structure that decouples the contact placement from the current distribution pattern.
Solution Approach 2:
The bus line serves as an intermediary conductive element between the electrode contacts and the active region. It mediates the current flow by providing a distributed pathway that spreads current laterally across the active region, preventing direct concentration at the contact points. This intermediary structure enables compact contact placement while maintaining emission uniformity.
2Area of stationary object
If contact distance is reduced to achieve compact design, then device area is decreased, but current distribution uniformity worsens leading to hot spots
Solution Approach 1:
The bus line extends the current pathway into the lateral dimension of the active region, creating a multi-dimensional current distribution network. This allows current to travel through additional pathways rather than directly between contacts, increasing the effective current path length while maintaining compact device area. The extended path reduces current density concentration that causes hot spots.
Solution Approach 2:
The bus line is strategically positioned to provide enhanced current distribution specifically in regions where hot spots would otherwise form. By placing the conductive bus line adjacent to or within the active region, the patent creates localized current redistribution that counteracts the formation of high-current-density zones near the contacts.
3Manufacturing precision
If current path length is increased to improve uniformity, then emission uniformity is improved, but resistive loss increases
Solution Approach 1:
The patent changes the electrical parameters of the current pathway by introducing the bus line with specific conductivity characteristics. The bus line material and geometry are selected to provide low resistance despite the increased path length, thereby maintaining energy efficiency while achieving improved current distribution and emission uniformity.
Data Source
AI summary
OLEDs and techniques for fabricating OLEDs are provided, in which the OLED has a shortest lateral current path through an active region that is longer than the shortest lateral electric field line within the active region. Such configurations prevent “hot spots” in the OLED panel, leading to a more uniform emission by the panel.