OLED Moisture Blocking Planarization Layer Design
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Solution Overview
Problem
Conventional OLED devices face reliability issues due to moisture intrusion through defects in the face seal structure, which can degrade the quality of the inorganic insulating layers and organic materials, especially when a planarization layer or bank is not formed in the non-active area, leading to potential moisture spread and degradation.
Innovation Solution
The OLED device incorporates moisture blocking portions at the planarization layer in the non-active area, which prevents foreign materials and moisture from entering the active area, utilizing a face seal structure with anode holes to outgas moisture and maintain environmental reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planarization layer or bank is not formed in the non-active area, then device complexity is reduced, but moisture can intrude through defects in the face seal structure and spread to the active area, degrading reliability
Solution Approach 1:
The planarization layer is segmented into different regions: a first planarization layer in the active area and a second planarization layer in the non-active area, with the second layer extending beyond the first layer's projection. This segmentation allows the structure to provide moisture blocking functionality in the non-active area without adding unnecessary complexity to the active area, thus resolving the contradiction between device complexity and reliability.
Solution Approach 2:
The second planarization layer is formed in advance in the non-active area, extending beyond the active area boundaries, to create a preliminary moisture blocking barrier. This preliminary action ensures that even if defects occur in the face seal structure, moisture has already been blocked by the extended planarization layer before it can reach the active area, thereby improving environmental reliability without significantly increasing overall device complexity.
2Ease of manufacture
If the face seal structure is simplified, then ease of manufacture is improved, but moisture intrusion through defects causes degradation of organic materials and inorganic insulating layers
Solution Approach 1:
The planarization layer is designed with local quality differentiation: the second planarization layer in the non-active area has extended coverage beyond the active area, providing enhanced moisture blocking capability specifically where needed. This localized enhancement allows the overall structure to remain relatively simple while effectively preventing moisture intrusion at critical locations, thus resolving the contradiction between ease of manufacture and protection against harmful factors.
3Reliability
If moisture blocking portions are added to the planarization layer, then reliability is improved, but device complexity increases
Solution Approach 1:
The moisture blocking functionality is merged with the planarization layer itself, rather than being implemented as a separate dedicated component. The second planarization layer serves dual purposes: maintaining planarity in the non-active area and providing moisture blocking capability. This merging approach improves reliability while minimizing the increase in device complexity, as the same structural element performs multiple functions.
Data Source
AI summary
Disclosed are an organic light emitting diode device, and a method for fabricating the same. The organic light emitting diode device comprises a non-active area formed outside an active area of a substrate; a switching thin film transistor and a driving thin film transistor at each of the pixel regions; a planarization layer on the substrate; a first electrode on the planarization layer; a bank formed in the non-active area outside each pixel region; an organic light emitting layer on the first electrode; a second electrode on an entire surface of the substrate; a first passivation layer on the substrate; an organic layer on the first passivation layer; a second passivation layer on the organic layer and the first passivation layer; a barrier film disposed to face the substrate.