OLED Contact Preventing Layer for Dark Spot Mitigation

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Solution Overview

Problem

Organic light emitting display devices often experience dark spots due to direct contact between the pixel defining layer and the electrode, or material diffusion, which affects the display's reliability and performance.

Innovation Solution

A display device structure incorporating a contact preventing layer made of inorganic material between the first electrode and the pixel defining layer, with a specific pattern and geometry to prevent direct contact and material diffusion, and a sub-contact preventing layer to further enhance protection, along with a method of fabricating this structure using photomasking and dry etching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the pixel defining layer is formed to define the pixel structure, then the pixel structure is well-defined, but direct contact between the pixel defining layer and electrode causes dark spots

Engineering Contradiction:

Improvepixel structure definitionVSAvoiddark spot occurrence

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

A contact preventing layer is introduced as an intermediary between the pixel defining layer and the electrode. This layer physically prevents direct contact between the pixel defining layer and electrode, thereby preventing dark spot formation while allowing the pixel defining layer to maintain its structural definition function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The structure is segmented into distinct functional layers: the pixel defining layer for structural definition, the contact preventing layer for preventing contact, and the electrode for electrical conduction. This segmentation allows each layer to perform its specific function without interfering with others.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the contact preventing layer is added to prevent dark spots, then dark spot occurrence is minimized, but device structure becomes more complex

Engineering Contradiction:

Improvedark spot occurrenceVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The contact preventing layer is merged with the pixel defining layer formation process. Both layers are formed in sequence using the same photomasking and etching processes, allowing the contact preventing layer to be integrated into the existing manufacturing flow without requiring separate processing steps.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The contact preventing layer uses the same material properties and formation parameters as the pixel defining layer, specifically using organic material with similar etching characteristics. This parameter consistency allows the contact preventing layer to be formed using the same process parameters, minimizing additional complexity.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the first electrode is formed with specific pattern, then electrical function is achieved, but material diffusion from pixel defining layer to electrode occurs

Engineering Contradiction:

Improveelectrical functionVSAvoidmaterial diffusion

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The contact preventing layer serves as a diffusion barrier between the pixel defining layer and the electrode. This intermediary layer blocks material diffusion from the pixel defining layer to the electrode while allowing the electrode to maintain its electrical function through the first opening.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The contact preventing layer, which physically blocks contact, also simultaneously prevents material diffusion. The same structural element that prevents direct contact also serves as a diffusion barrier, converting a potential harm (material diffusion) into a beneficial effect through the contact preventing layer's physical presence.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11678527B2Display device and method of fabricating the same

Publication Date: 2023.06.13 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a planarization layer disposed on a substrate, a first electrode disposed on the planarization layer and including silver (Ag), a contact preventing layer disposed on the first electrode, including a light absorbing material, and including a top surface and a side surface extending from an end of the top surface, and a pixel defining layer disposed on the contact preventing layer and including a bottom surface facing the top surface of the contact preventing layer, and a side surface extending from an end of the bottom surface. The first electrode includes a first region overlapping pixel defining layer. The contact preventing layer includes a second region overlapping the first region between the first electrode and the pixel defining layer. A first edge where the top and side surfaces of the contact preventing layer meet is located on the bottom surface of the pixel defining layer.