OLED Display Undercut Structure for Moisture-Resistant Through-Holes
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Solution Overview
Problem
Conventional display devices face challenges in preventing moisture ingress through openings, which can degrade organic light-emitting diodes (OLEDs), particularly in flexible substrates with through-holes.
Innovation Solution
A stepped portion with an under-cut structure is introduced in the substrate, disconnecting the intermediate and opposite electrode layers, and a protective layer is applied to block moisture ingress, using a combination of inorganic and organic-inorganic composite particles to enhance barrier characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a through-hole opening is provided in the substrate for component mounting or display purposes, then device functionality and design flexibility are improved, but moisture ingress paths are created that threaten OLED reliability
Solution Approach 1:
The electrode layers are segmented into multiple disconnected portions by the stepped structure. The intermediate layer and opposite electrode layer are divided into first portions extending toward the opening and second portions disconnected from the opening, creating isolated functional zones that maintain OLED reliability while allowing through-hole functionality
Solution Approach 2:
A stepped portion is introduced in the thickness direction (third dimension) of the substrate, creating a vertical relief structure. This dimensional change allows the electrode layers to extend toward the opening in the planar direction while being disconnected by the stepped portion, effectively blocking moisture paths without compromising device functionality
2Ease of operation
If electrode layers extend toward the opening to maintain electrical connectivity, then device functionality is preserved, but moisture can more easily reach and degrade the OLEDs
Solution Approach 1:
The electrode layers are segmented into first portions that extend toward the opening for electrical connectivity and second portions that are disconnected from the opening to prevent moisture access. This segmentation allows the structure to simultaneously achieve both electrical functionality and moisture protection
Solution Approach 2:
The stepped portion acts as an intermediary barrier between the electrode layers and the opening. It allows the electrode layers to extend toward the opening while being disconnected by the stepped portion, effectively mediating between the need for electrical connectivity and the need to block moisture ingress
3Reliability
If a stepped portion with under-cut step is introduced to block moisture paths, then OLED protection is improved, but manufacturing complexity increases
Solution Approach 1:
The stepped portion is localized specifically in the third area between the opening and pixel array, rather than throughout the entire substrate. This local modification creates the necessary moisture barrier while minimizing overall structural complexity and maintaining simplicity in other regions
Data Source
AI summary
An organic light-emitting display including a substrate, an insulating layer on the substrate, the substrate and the insulating layer having an opening therethrough penetrating, a pixel array on the insulating layer, the pixel array including a plurality of pixels that surround the opening, a first pixel adjacent to the opening from among the plurality of pixels includes a pixel electrode layer, an intermediate layer on the pixel electrode layer, and an opposite electrode layer on the intermediate layer, and a stepped portion on the substrate and adjacent to the opening, the stepped portion having an under-cut step, wherein the intermediate layer including an organic emission layer, and wherein at least one of the intermediate layer and the opposite electrode layer extends toward the opening and is disconnected by the stepped portion.