OLED Anode Planarization Layer Hillock Management

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Solution Overview

Problem

Current OLED display panels face issues with hillocks forming on the anode layer during manufacturing, leading to short circuits and non-light-emitting areas, which affect the display effect due to poor film-forming uniformity and resulting in black spots.

Innovation Solution

A planarization layer is disposed on the side of the anode layer away from the substrate to cover the hillocks, preventing short circuits and ensuring a planar surface for the organic functional layer, with a wrapping layer optionally used to prevent hillocks from piercing the planarization layer, and materials with similar work functions are chosen to maintain hole transport efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a planarization layer is added to cover hillocks on the anode layer, then short circuits are prevented and display quality is improved, but device structure becomes more complex

Engineering Contradiction:

Improveshort circuit preventionVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A planarization layer is introduced as an intermediary component between the anode layer and the organic functional layer. This intermediate layer specifically addresses the hillock problem by providing a planar surface that prevents short circuits while maintaining the functional integrity of the device.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The device structure is segmented into distinct functional layers, with the planarization layer being a separate, dedicated component. This segmentation allows each layer to perform its specific function independently, with the planarization layer focused solely on surface planarity and short circuit prevention.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If the anode layer is made with poor film-forming uniformity, then manufacturing is simpler, but hillocks form causing short circuits and black spots

Engineering Contradiction:

Improveanode layer fabricationVSAvoidfilm uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The planarization layer is applied in advance before depositing the organic functional layer. This preliminary action corrects the surface uniformity issues of the anode layer before subsequent layers are added, preventing hillocks from causing defects in the final device.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The planarization layer serves as a cushioning layer that compensates for the poor film-forming uniformity of the anode layer. By providing this protective intermediate layer, the negative effects of anode layer imperfections are prevented from propagating to the organic functional layer.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If material with different work function is used for planarization layer, then material selection is more flexible, but hole transport efficiency decreases

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidhole transport efficiency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The work function of the planarization layer material is carefully selected and controlled to match or be close to the work function of the anode layer material. This parameter matching ensures efficient hole transport from the anode through the planarization layer to the organic functional layer.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11925048B2Display panel, method for manufacturing same, and display device

Publication Date: 2024.03.05 HEFEI BOE ZHUOYIN TECH CO LTD

AI summary

Provided is a display panel. The display panel includes a substrate, an anode layer, a planarization layer and an organic functional layer. The anode layer is disposed on a side of the substrate, the planarization layer is disposed on a side of the anode layer away from the substrate and configured to cover the anode layer, and the organic functional layer is disposed on a side of the planarization layer away from the anode layer.