OLED Encapsulation with Alternating Organic-Inorganic Layers
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Solution Overview
Problem
Organic light-emitting devices (OLEDs) suffer from dark spots due to cathode oxidation caused by plasma damage during thin film encapsulation, which results in gas permeation and defects.
Innovation Solution
An organic light-emitting device with an encapsulation layer featuring an alternating stack structure of organic and inorganic layers, where the organic layer is polymerized from specific monomers that include a phenyl ring to reduce plasma damage and enhance packing, thereby decreasing gas transmissibility and outgas diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma processing is used during thin film encapsulation, then inorganic layers can be deposited effectively, but plasma damage occurs to the organic layers causing cathode oxidation and dark spots
Solution Approach 1:
The patent introduces a protective organic layer as an intermediary between the cathode and the plasma processing environment. This protective layer acts as a buffer that absorbs plasma damage, preventing direct contact between plasma and the cathode, thereby eliminating cathode oxidation and dark spot formation while maintaining effective encapsulation.
Solution Approach 2:
The patent creates an inert environment by using specific organic materials with low plasma reactivity in the encapsulation layers. These materials resist plasma attack, providing a protective atmosphere that prevents oxidation of the cathode during plasma-based thin film deposition processes.
2Ease of manufacture
If conventional encapsulation structures are used, then manufacturing is simpler, but gas permeation occurs leading to oxidation and defects
Solution Approach 1:
The patent employs a composite encapsulation structure consisting of alternating organic and inorganic layers. The inorganic layers provide gas permeation resistance while the organic layers provide flexibility and adhesion. This composite structure achieves superior protection against gas permeation and oxidation compared to single-material encapsulation, while remaining compatible with conventional manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces the occurrence of dark spots during reliability tests by minimizing plasma-induced damage and improving the encapsulation effectiveness, leading to a more reliable OLED performance.
Implementation Method 1
the organic layer including a polymer polymerized from monomers of Formula 1 and Formula 2
Implementation Method 2
the encapsulation layer having an alternating stack structure of an organic layer and an inorganic layer
Data Source
AI summary
An organic light-emitting device including: a substrate; a display unit on the substrate; and an encapsulation layer covering the display unit, the encapsulation layer having an alternating stack structure of an organic layer and an inorganic layer, and the organic layer including a polymer polymerized from monomers of Formula 1 and Formula 2: