OLED Display Substrate with Transfer-Printed Auxiliary Electrode
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Solution Overview
Problem
Current top-emission OLED technologies face challenges with high resistance in large-area metal top electrodes and damage from photolithography processes, which hinder the development of thin and efficient OLED display devices.
Innovation Solution
A display substrate design featuring a shared top electrode layer with conductive structures and an auxiliary electrode formed without relying on a package cover plate, using a transfer process to minimize thickness and avoid photolithography-related damage, and an adhesive layer for structural fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large-area metal top electrode is used in top-emission OLED, then the electrode can cover the entire light-emitting area, but the resistance increases significantly
Solution Approach 1:
The patent divides the large-area top electrode into multiple sub-electrodes corresponding to different sub-pixel regions (red, green, blue sub-pixels). Each sub-electrode has a smaller area and lower resistance compared to a single large electrode. The sub-electrodes are electrically connected through conductive structures to form the complete top electrode system, thus reducing overall resistance while maintaining full light-emitting area coverage.
2Manufacturing precision
If photolithography process is used to fabricate OLED structures, then precise patterning can be achieved, but damage occurs to the organic light emitting layer
Solution Approach 1:
The patent extracts and removes the photolithography process from the OLED fabrication sequence. Instead of using photolithography to pattern the top electrode and other structures, the invention employs a transfer printing process where pre-patterned structures are transferred onto the OLED stack. This eliminates the harmful effects of photolithography (chemical exposure, UV radiation, etching) on the sensitive organic light emitting layer while still achieving precise patterning through the transfer process.
Solution Approach 2:
The patent performs patterning actions in advance during the transfer printing process rather than in-situ on the completed OLED. The top electrode and other structures are pre-formed on a separate substrate with precise patterns, then transferred onto the OLED stack. This preliminary action allows precise patterning to be achieved without exposing the light emitting layer to damaging photolithography conditions.
3Stability of the object's composition
If a package cover plate is used to support the auxiliary electrode, then the electrode structure is stable, but the device thickness increases
Solution Approach 1:
The patent merges the auxiliary electrode structure with the top electrode layer by forming the auxiliary electrode directly on the top electrode using the transfer printing process. This integration eliminates the need for a separate package cover plate to support the auxiliary electrode, as the auxiliary electrode is now structurally combined with the existing top electrode layer. The merged structure maintains stability while reducing overall device thickness by removing the redundant cover plate.
Data Source
AI summary
A display substrate includes a base substrate provided thereon with a pixel defining layer and a plurality of organic light emitting diodes, a plurality of conductive structures are provided on a side of a top electrode layer away from the base substrate, the top electrode layer being on the pixel defining layer, an orthographic projection of the conductive structures on a plane where the pixel defining layer is within an area where the pixel defining layer is disposed, the conductive structures are coupled to a portion of the top electrode layer on the pixel defining layer, the remaining portion of the top electrode layer is provided with a planarization layer on a side of the top electrode layer away from the base substrate, and an auxiliary electrode is on a side of the planarization layer away from the base substrate, and is coupled to the conductive structures.