OLED Pixel Defining Layer Notch Design for Ink Climbing

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Solution Overview

Problem

Conventional organic light-emitting devices with trapezoidal pixel defining layers are prone to ink climbing, leading to short circuits and electric leakage due to the anode forming on the side wall, affecting the display effect.

Innovation Solution

A display panel design featuring a substrate with a pixel defining layer and banks that include notches, where the first electrode is positioned at the bottom of openings and extends into the notch, ensuring its height is less than or equal to the maximum notch height, preventing ink climbing and potential short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a conventional trapezoidal pixel defining layer is used, then the structure is simple, but ink climbing occurs causing short circuits and electric leakage

Engineering Contradiction:

Improvepixel defining layer structureVSAvoidrisk of short circuit and electric leakage

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The bank structure transitions from a conventional symmetric trapezoidal shape to an asymmetric design with a notch on one side wall. This asymmetric notch structure prevents the anode from climbing along the side wall, thereby eliminating the short circuit issue while maintaining structural simplicity

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

A notch is extracted or removed from the side wall of the bank, creating a discontinuity in the side wall structure. This extracted portion prevents the continuous path that would allow ink climbing, thus solving the reliability problem without significantly complicating the overall structure

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the first electrode extends into the notch, then the risk of electric leakage is reduced, but the manufacturing precision requirement increases

Engineering Contradiction:

Improveelectric leakage preventionVSAvoidelectrode position and height control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The notch is pre-formed in the bank structure before the first electrode is deposited. This preliminary action creates a built-in constraint that guides the electrode formation process, allowing the electrode to naturally extend into the notch without requiring extremely precise control during the deposition step

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The notch structure serves a dual function: it prevents ink climbing and simultaneously guides the electrode formation. The electrode's extension into the notch is self-regulated by the notch's geometry, reducing the need for external precision control mechanisms

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11387298B2Display panel, fabrication method thereof, and display device

Publication Date: 2022.07.12 BEIJING BOE TECH DEV CO LTD

AI summary

A display panel, a fabrication method thereof, and a display device are disclosed. The display panel includes: a substrate; a pixel defining layer located on the substrate, the pixel defining layer including: a plurality of openings and a bank enclosing each opening, the bank including a notch; and a first electrode, located at a bottom of each opening and extending into the notch, wherein with respect to a plane where the substrate is located, a height of the first electrode is less than or equal to a maximum height of the notch.