OLED Interconnecting Layer Dopant Gradient

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Solution Overview

Problem

Existing organic light emitting devices face challenges in maintaining efficient charge injection and minimizing dopant diffusion, leading to increased driving voltage and reduced lifespan due to uniform dopant concentrations in charge generation layers.

Innovation Solution

Incorporating a concentration gradient of p-type and n-type dopants in the charge generation layers, with the highest p-type dopant concentration at the interface and increasing n-type dopant concentration away from it, to optimize charge injection and prevent dopant diffusion, thereby reducing energy barriers and maintaining efficient operation over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform dopant concentration is used in charge generation layers, then manufacturing is simpler, but charge injection efficiency decreases and dopant diffusion increases

Engineering Contradiction:

Improvesimplicity of dopant distributionVSAvoidcharge injection efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating non-uniform dopant concentration distributions within the charge generation layers. The p-type charge generation layer has higher dopant concentration near the interface with the n-type layer, while the n-type charge generation layer has higher dopant concentration away from the interface. This localized variation in dopant concentration optimizes charge injection efficiency at different positions within the layers, resolving the contradiction between manufacturing simplicity and device reliability.

Inventive Principle:

Principle #3Local quality

2Device complexity

If uniform dopant concentration is used in charge generation layers, then device structure is simpler, but dopant diffusion increases leading to reduced lifespan

Engineering Contradiction:

Improveuniformity of dopant distributionVSAvoiddevice lifespan

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The patent implements local quality by establishing specific dopant concentration gradients in the charge generation layers. The p-type layer exhibits higher dopant concentration at the interface region, while the n-type layer shows higher concentration in the bulk region away from the interface. This spatially differentiated dopant distribution reduces dopant diffusion by creating more stable concentration profiles, thereby extending device lifespan without significantly increasing structural complexity.

Inventive Principle:

Principle #3Local quality

3Reliability

If higher dopant concentration is used throughout, then charge injection efficiency improves, but dopant diffusion increases

Engineering Contradiction:

Improvecharge injection efficiencyVSAvoiddopant diffusion

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent resolves this contradiction by applying local quality through position-dependent dopant concentrations. In the p-type charge generation layer, higher dopant concentration is localized near the interface to enhance charge injection, while the bulk region maintains lower concentration to minimize diffusion. Conversely, in the n-type charge generation layer, higher concentration is positioned away from the interface to optimize injection while reducing overall diffusion. This strategic localization of high dopant concentration achieves both improved charge injection efficiency and reduced dopant loss.

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 a light emitting device with lower driving voltage and extended lifespan by ensuring efficient charge injection and preventing dopant diffusion, enhancing the overall efficiency and longevity of the device.

Implementation Method 1

Each interconnecting layer includes a p-type charge generation layer doped with a p-type dopant and an n-type charge generation layer doped with an n-type dopant

Methodology Applied

Scientific EffectDoping: Dopants

Implementation Method 2

At least one of the p-type charge generation layer and the n-type charge generation layer has a concentration gradient of the p-type dopant or the n-type dopant

Methodology Applied

Scientific EffectConcentration gradient: Density Gradient

Implementation Method 3

an organic layer interposed between the electrodes, which is an active light emitting device using a phenomenon in which when a current flows through the electrodes, light is emitted while electrons and holes injected through the electrodes are combined in the organic layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10153452B2Organic light emitting device

Publication Date: 2018.12.11 SAMSUNG DISPLAY CO LTD

AI summary

A light emitting device including a first electrode, a light emitting portion on the first electrode, the light emitting portion including a plurality of light emitting units and at least one interconnecting layer between ones of the light emitting units that are adjacent to each other, and a second electrode on the light emitting portion. The at least one interconnecting layer includes a p-type charge generation layer doped with a p-type dopant and an n-type charge generation layer doped with an n-type dopant. At least one of the p-type charge generation layer and the n-type charge generation layer has a concentration gradient of the p-type dopant or the n-type dopant.