OLED Pixel Defining Layer Ink Volume Control

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Solution Overview

Problem

Current pixel defining layer designs for OLEDs face challenges in achieving film formation uniformity while adhering to narrow-frame design requirements, as dummy pixels are needed to compensate for faster solvent drying rates at the edge zone, leading to increased frame area and reduced screen-to-body ratio.

Innovation Solution

A pixel defining layer with a double-layered structure, where the first inorganic sub-layer and second organic sub-layer define ink-holding spaces, with the dummy zone having larger ink-holding spaces and reduced pixel density, allowing for increased ink volume in the dummy zone without compromising film uniformity, thereby reducing the number of dummy pixels and achieving a narrower frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If dummy pixels are added to compensate for faster solvent drying rates at the edge zone, then film formation uniformity is improved, but frame area increases and screen-to-body ratio decreases

Engineering Contradiction:

Improvefilm formation uniformityVSAvoidframe area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The pixel defining layer is designed with different structures in different zones: the active area zone has a first pixel defining layer with specific width, while the dummy zone has a second pixel defining layer with larger width to create larger ink-holding spaces. This local differentiation allows the dummy zone to hold more ink and compensate for faster drying rates without expanding the overall frame area uniformly across the entire device.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention transitions from a single-layer pixel defining structure to a multi-layer structure with first and second pixel defining layers stacked in the vertical dimension. This dimensional change enables independent optimization of ink-holding capacity in the dummy zone through the second layer, while maintaining the original active area structure, thereby resolving the contradiction between film uniformity and frame area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the pixel defining layer width is increased to hold more ink in the dummy zone, then film formation uniformity is improved, but the device complexity increases

Engineering Contradiction:

Improvefilm formation uniformityVSAvoidpixel defining layer structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The pixel defining layer is segmented into functionally distinct first and second layers, where the first pixel defining layer handles active area pixel definition and the second pixel defining layer specifically addresses dummy zone ink-holding requirements. This segmentation allows each layer to be optimized for its specific function, improving film formation uniformity while keeping the overall structure manageable through clear functional division.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design ensures uniform film formation and reduces the number of dummy pixels in the edge zone, enhancing the screen-to-body ratio by controlling ink volume and distribution, thus achieving a stable and effective narrow-frame design.

Implementation Method 1

the first pixel defining sub-layer is an inorganic pixel defining sub-layer having lyophilicity, and the second pixel defining sub-layer is an organic pixel defining sub-layer having lyophobicity

Methodology Applied

Scientific EffectLyophilicity: Hydrophile

Implementation Method 2

the first pixel defining sub-layer is an inorganic pixel defining sub-layer having lyophilicity, and the second pixel defining sub-layer is an organic pixel defining sub-layer having lyophobicity

Methodology Applied

Scientific EffectLyophobicity: Hydrophobe

Data Source

PatentUS10546904B2Pixel defining layer having pixel defining sub-layers

Publication Date: 2020.01.28 BOE TECHNOLOGY GROUP CO LTD

AI summary

Provided is a pixel defining layer for pixels formed by ink jet printing, an array substrate and a display apparatus. The pixel defining layer comprises a first pixel defining sub-layer, which defines a plurality of uniformly distributed pixels; and a second pixel defining sub-layer on the first pixel defining sub-layer, wherein the second pixel defining sub-layer and the first pixel defining sub-layer together define a plurality of ink-holding spaces for the plurality of uniformly distributed pixels respectively, and wherein a width of the first pixel defining sub-layer is not less than a width of the second pixel defining sub-layer thereon, wherein the pixel defining layer is divided into an active area zone and an dummy zone outside the active area zone, and wherein an ink-holding space of a pixel in the dummy zone is larger than an ink-holding space of a pixel in the active area zone.