OLED Layer Stack Segmentation for Light Emission and Transmittance

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Solution Overview

Problem

Current organic light emitting display (OLED) devices face challenges in optimizing both light emitting efficiency and transmittance properties, particularly in the design and manufacturing process, which affects their overall performance and efficiency.

Innovation Solution

The OLED device incorporates a unique layer stack structure on the pixel area for light emitting efficiency and a transmittance optimizing structure on the transmission area, using materials like hole transport layers, electron transport layers, and transparent organic materials, along with a specific arrangement of electrodes and layers to enhance both light emission and transmittance without compromising the optical resonance structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a uniform layer stack structure is used across the entire display area, then manufacturing simplicity is maintained, but light emitting efficiency and transmittance properties cannot be simultaneously optimized for different functional areas

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfunctional optimization for different areas
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The display area is divided into two distinct functional zones: a pixel area with a first layer stack structure optimized for light emission, and a transmission area with a second layer stack structure optimized for light transmission. This segmentation allows each area to have independently optimized structures without compromising the other, resolving the contradiction between manufacturing simplicity and functional adaptability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different layer stack structures are applied to different spatial locations based on their specific functional requirements. The pixel area receives a structure with multiple organic layers (hole transport, emission, electron transport layers) for optimal light emission, while the transmission area receives a simplified structure with fewer layers for optimal light transmission. This local differentiation enables both areas to perform at their best.

Inventive Principle:
Principle #3Local quality

2Illumination intensity

If the layer stack structure is optimized for light emitting efficiency in the pixel area, then light emission performance is improved, but transmittance properties in the transmission area are compromised

Engineering Contradiction:
Improvelight emitting efficiencyVSAvoidtransmittance properties
Core Design Contradiction:
Illumination intensityVSQuantity of substance

Solution Approach 1:

The display surface is segmented into pixel and transmission areas, each with dedicated layer stack structures. The pixel area uses a comprehensive multi-layer organic structure for high light emission efficiency, while the transmission area uses a simplified structure with reduced organic layers to maximize light transmission, thus resolving the trade-off between emission efficiency and transmittance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The layer stack composition is locally adapted: the pixel area contains hole transport layer, emission layer, and electron transport layer for optimal electroluminescence, while the transmission area has fewer organic layers to minimize optical absorption and maximize transmittance. This local optimization allows both functions to excel simultaneously.

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If the layer stack structure is optimized for transmittance in the transmission area, then light transmission is improved, but light emitting efficiency in the pixel area deteriorates

Engineering Contradiction:
Improvetransmittance propertiesVSAvoidlight emitting efficiency
Core Design Contradiction:
Quantity of substanceVSIllumination intensity

Solution Approach 1:

By segmenting the display into pixel and transmission areas with different layer stack structures, the patent ensures that the transmission area's simplified structure (optimized for transmittance) does not interfere with the pixel area's comprehensive structure (optimized for light emission). Each area's structural optimization is isolated to its specific function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The layer stack is locally configured: transmission areas have reduced organic layers for maximum light transmission, while pixel areas maintain the full complement of hole transport, emission, and electron transport layers for optimal light generating efficiency. This local differentiation eliminates the trade-off between transmittance and emission efficiency.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If different layer stack structures are used for pixel and transmission areas, then functional performance is optimized, but manufacturing complexity increases

Engineering Contradiction:
Improvefunctional performance optimizationVSAvoidmanufacturing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the display into pixel and transmission areas with distinct layer stack structures. While this creates structural complexity, it enables independent optimization of each area's functional performance, with the pixel area specialized for light emission and the transmission area specialized for light transmission.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different layer stack configurations are applied locally to match functional requirements: pixel areas receive comprehensive organic layers for electroluminescence, while transmission areas receive simplified structures for optical clarity. This local quality differentiation achieves superior functional performance despite increased manufacturing complexity.

Inventive Principle:
Principle #3Local quality

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 approach results in improved light emitting efficiency and transmittance properties, optimizing the OLED device's performance by selectively enhancing transmittance in the transmission area without disturbing the light emitting properties on the pixel area.

Implementation Method 1

an organic layer interposed between the plurality of first pixel electrodes and the second pixel electrode, and including an emission layer

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

including a reflection layer formed of a light-reflecting conductive material

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

a second pixel electrode formed of a light-transmitting conductive material

Methodology Applied
Scientific EffectLight transmission:

Data Source

PatentEP2988333B1Organic light emitting display devices and methods of manufacturing the same
Publication Date: 2022.01.12 SAMSUNG DISPLAY CO LTD
  • EP2988333B1 patent drawingFigure 1
  • EP2988333B1 patent drawingFigure 2~3
  • EP2988333B1 patent drawingFigure 4~5

AI summary

An OLED device and a method of manufacturing the same, the OLED device including a substrate having a pixel area and a transmission area; a pixel circuit on the pixel area; a first electrode on the pixel area and being electrically connected to the pixel circuit; a first organic layer extending continuously on the pixel area and the transmission area and covering the first electrode; an emitting layer selectively on a portion of the first organic layer on the pixel area; a second organic layer extending continuously on the pixel and transmission areas and covering the emitting layer; and a third organic layer selectively on the transmission area, the third organic layer including a non-emitting material that has a different transmittance from that of the emitting layer; and a second electrode extending continuously on the pixel area and the transmission area and covering the second and third organic layers.