Transparent Conductive OLED Encapsulation for Moisture Barrier
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Solution Overview
Problem
Existing display devices, particularly head-mounted displays, face challenges in providing high-resolution images while maintaining effective moisture permeation prevention, which is crucial for ensuring the longevity and performance of organic light-emitting diode (OLED) displays.
Innovation Solution
The display device incorporates a multilayer encapsulation structure comprising a first and second sub-encapsulation layer, with the second layer containing a transparent conductive material, such as IZO and AlOx, to enhance moisture barrier properties and maintain high current driving capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer encapsulation structure is used, then the device structure is simple, but the moisture barrier function is insufficient
Solution Approach 1:
The encapsulation layer is divided into multiple sub-layers (first sub-encapsulation layer, second sub-encapsulation layer, and third sub-encapsulation layer) with different material compositions and functions. Each layer provides specific protection against moisture and oxygen, creating a multi-barrier system that significantly improves the overall moisture barrier function compared to a single-layer structure.
Solution Approach 2:
The encapsulation structure uses composite materials with different properties in each layer. The first sub-encapsulation layer uses a metal oxide (e.g., AlOx) for excellent barrier properties, the second sub-encapsulation layer uses a transparent conductive material (e.g., IZO) for both barrier and electrical functionality, and the third sub-encapsulation layer uses another metal oxide for additional protection. This composite approach optimizes both moisture barrier performance and device functionality.
2Reliability
If the encapsulation layer uses only insulating materials, then the moisture barrier is effective, but the current driving capability is reduced
Solution Approach 1:
The second sub-encapsulation layer is designed to perform multiple functions simultaneously: it provides moisture and oxygen barrier protection like traditional insulating layers, while also serving as a transparent conductive layer that maintains electrical connectivity and current driving capability. This multi-functional layer eliminates the need for separate conductive and barrier layers, resolving the contradiction between moisture protection and electrical performance.
Solution Approach 2:
The use of transparent conductive oxide materials (such as IZO - indium zinc oxide) in the second sub-encapsulation layer creates a composite structure that combines the barrier properties of metal oxides with the electrical conductivity of transparent conductors. This allows the encapsulation layer to simultaneously prevent moisture permeation and maintain high current driving capability for the OLED pixels.
Data Source
AI summary
A display device includes: a substrate; a first electrode on the substrate; a pixel defining film on the first electrode; a light emitting stack on the first electrode and the pixel defining film; a second electrode on the light emitting stack; and an encapsulation layer on the second electrode, wherein the encapsulation layer comprises a first sub-encapsulation layer on the second electrode and a second sub-encapsulation layer on the first sub-encapsulation layer, and the second sub-encapsulation layer contains a transparent conductive material. In addition, an electronic device including the display device is also provided.