Step-Shaped Contact Electrode for OLED Electrical Connection
Solution Overview
Problem
The top emission type organic light emitting display devices face challenges in achieving reliable electrical connections between the cathode and auxiliary electrodes due to the difficulty in controlling the Post Exposure Bake (PEB) process for creating a reversed tapered structure, which can lead to structural issues such as collapse or peeling of the partition, disrupting the electrical connection.
Innovation Solution
The solution involves a step-shaped contact electrode with a hollow space between its portions, allowing direct connection of the cathode electrode to the auxiliary electrode without the need for a reversed tapered partition, using a multi-layered structure with varying thicknesses and corrosion resistances to enhance electrical connectivity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a partition with reversed tapered structure is used to prevent organic emitting layer deposition, then the electrical connection between cathode and auxiliary electrode is achieved, but the manufacturing precision deteriorates due to difficulty in controlling the PEB process
Solution Approach 1:
The patent removes the partition structure entirely and extracts only the essential function of electrical connection. The auxiliary electrode is directly exposed in the pixel region without being covered by the organic emitting layer, achieving electrical connection without requiring the problematic reversed tapered partition structure that caused manufacturing precision issues.
Solution Approach 2:
Instead of using a partition structure to prevent organic emitting layer deposition (as in conventional designs), the patent inverts the approach by directly exposing the auxiliary electrode in the pixel region. This inversion eliminates the need for complex partition formation while achieving the same electrical connection function.
2Manufacturing precision
If a partition with reversed tapered structure is used to define pixel region, then the organic emitting layer deposition is controlled, but the structural stability deteriorates due to partition collapse or peeling
Solution Approach 1:
The patent removes the partition structure entirely, extracting only the essential functions of pixel region definition and organic emitting layer deposition control. The bank structure alone is sufficient to define the pixel region, making the additional partition structure unnecessary and eliminating its stability problems.
Solution Approach 2:
The bank structure is given multiple functions: it defines the pixel region, controls organic emitting layer deposition, and provides structural support. By making the bank multi-functional, the patent eliminates the need for a separate partition structure that would require additional stability considerations.
3Illumination intensity
If the cathode electrode is formed of transparent conductive material to allow light emission, then the light transmission is improved, but the electrical resistance increases
Solution Approach 1:
The patent merges the cathode electrode and auxiliary electrode functions into a single integrated structure. The auxiliary electrode in the pixel region serves both as the cathode for light emission (requiring transparency) and as the electrical connection path (requiring low resistance), eliminating the need for separate electrodes and their complex interconnections.
Solution Approach 2:
The auxiliary electrode is positioned and configured in advance to provide both optical and electrical functions. By preliminarily establishing the auxiliary electrode's position and structure in the pixel region, the patent ensures both light transmission and electrical conductivity requirements are met from the outset, avoiding subsequent connection issues.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Disclosed is an organic light emitting display device that may include an anode electrode (180, 200); an organic emitting layer (240) on the anode electrode; a cathode electrode (250) on the organic emitting layer; an auxiliary electrode (190) electrically connected with the cathode electrode; and a contact electrode (190a) that is on a same layer as the auxiliary electrode, the contact electrode horizontally spaced apart from the auxiliary electrode, the contact electrode directly connected with both the auxiliary electrode and the cathode electrode to connect together the auxiliary electrode and a portion of the cathode electrode that is on a same layer as the auxiliary electrode.