Reflective Electrode Layout for Residue-Free LED Display Openings
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Solution Overview
Problem
The challenge is to address the issue of residues that may occur between pad electrodes when forming reflective electrodes in display devices, while also reducing light leakage to the bottom of the light-emitting element.
Innovation Solution
A display device is designed with a substrate having first and second pad electrodes, a bank defining openings to expose portions of these electrodes, an inter-electrode planarization layer between the electrodes, and reflective electrodes extending from the bank to this layer. An organic pattern layer is applied in the openings, and a light-emitting element is placed on top, with lead lines electrically connecting the contact electrodes and reflective electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reflective electrodes are formed directly on pad electrodes, then electrical connection is achieved, but residues occur between pad electrodes
Solution Approach 1:
An inter-electrode planarization layer is introduced as an intermediary between the pad electrodes and reflective electrodes. This layer prevents direct contact that causes residue formation while maintaining electrical connection through its conductive properties or by allowing reflective electrode extension onto it.
Solution Approach 2:
The inter-electrode planarization layer is formed in advance before depositing the reflective electrodes. This preliminary action creates a prepared surface that prevents residue formation during subsequent reflective electrode formation processes.
2Reliability
If pad electrodes are exposed, then electrical connection is established, but light leakage to the bottom occurs
Solution Approach 1:
The inter-electrode planarization layer is selectively positioned between pad electrodes while allowing their exposure for connection. This localized structure blocks light leakage in specific areas where electrodes are covered, while maintaining electrical connection where electrodes are exposed.
3Manufacturing precision
If inter-electrode planarization layer is added, then residues are prevented and light leakage is reduced, but device complexity increases
Solution Approach 1:
The inter-electrode planarization layer serves multiple functions simultaneously: it prevents residue formation during reflective electrode deposition, blocks light leakage to the substrate, and provides a planar surface for subsequent processing. This multi-functionality justifies the added structural complexity.
Data Source
AI summary
A display device includes a substrate including first and second pad electrodes, a bank defining a first opening, and exposing portions of the first and second pad electrodes through the first opening, an inter-electrode planarization layer between the first and second pad electrodes, a first reflective electrode extending from the bank to the inter-electrode planarization layer along the first pad electrode, a second reflective electrode extending from the bank to the inter-electrode planarization layer along the second pad electrode, an organic pattern layer in the first opening, a light-emitting element having a first contact electrode and a second contact electrode on a top surface thereof, a via layer covering the light-emitting element and defining contact holes, and first and second lead lines above the via layer and electrically connecting the first contact electrode and the first reflective electrode, and electrically connecting the second contact electrode and the second reflective electrode.