OLED Insulating Film Segmentation for Aperture Ratio and Reliability

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Solution Overview

Problem

Existing organic light emitting devices with moderately tapered-shaped insulating films suffer from a lowered aperture ratio, particularly in small and high-definition displays, due to excessive coverage of the first electrode, leading to potential disconnection of the organic layer and second electrode, which affects device characteristics.

Innovation Solution

The implementation of an insulating film with internal wall surfaces that have multiple faces with different inclined angles, where one face is precipitous to secure the aperture size and another face is moderately inclined to prevent disconnection of the second electrode, and the provision of corner sections or inclined surfaces in the insulating film to enhance insulation and reduce current concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a moderately tapered-shaped insulating film is used to prevent disconnection of the organic layer and second electrode, then reliability is improved, but the aperture ratio is lowered

Engineering Contradiction:

Improvedevice characteristicsVSAvoidaperture ratio

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The insulating film is segmented into multiple regions with different shapes: a first region with a substantially vertical side surface that minimizes coverage of the first electrode, and a second region with a tapered side surface that prevents disconnection. This segmentation allows each region to fulfill its specific function optimally.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the insulating film are given different local qualities: the first region has a vertical profile for maximizing aperture ratio, while the second region has a tapered profile for ensuring reliability. This local differentiation resolves the contradiction between aperture ratio and device reliability.

Inventive Principle:

Principle #3Local quality

2Reliability

If the insulating film covers the rim of the first electrode extensively, then insulation between electrodes is improved, but the aperture ratio is reduced

Engineering Contradiction:

Improveinsulation between electrodesVSAvoidaperture ratio

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The insulating film structure is divided into a first region covering part of the first electrode rim with vertical sides for minimal coverage, and a second region extending further with tapered sides for enhanced insulation. This segmentation provides both adequate insulation and maximum aperture ratio.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insulating film utilizes three-dimensional spatial arrangement with vertical and tapered portions at different locations, allowing it to provide comprehensive insulation coverage without excessively reducing the aperture area in the planar dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS9190460B2Organic light emitting device and display unit including the same

Publication Date: 2015.11.17 SONY GROUP CORP

AI summary

An organic light emitting device includes a first electrode and a second electrode, an organic layer including a light emitting layer between the first electrode and the second electrode, and an insulating film covering a rim of the first electrode from a surface thereof to a side surface thereof, and having an internal wall surface being in contact with the organic layer, and one or more corner sections in the internal wall surface with a ridge line thereof in parallel with the surface of the first electrode.