OLED Hole Transport Layer Capacitance for Low-Voltage Emission

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Solution Overview

Problem

Organic light-emitting devices face challenges with efficiency, lifespan, and driving voltage, particularly due to hole accumulation phenomena in the hole transport layer leading to capacitance increases and poor charge transfer, resulting in low-gray phenomena and image quality deterioration.

Innovation Solution

The use of an organic electronic element with a hole transport region having a capacitance of less than 1 nF within 0 V to 1 V, utilizing a compound that minimizes capacitance changes and enhances charge transfer efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional organic material layer materials are used, then the device structure is simple, but hole accumulation occurs leading to increased capacitance and deteriorated image quality

Engineering Contradiction:

Improveimage qualityVSAvoidmaterial layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the hole transport layer into multiple sub-layers with different materials (first hole transport layer, second hole transport layer, third hole transport layer) to prevent hole accumulation at interfaces. Each layer has specific capacitance requirements (less than 1 nF) and material specifications to ensure smooth charge transfer and maintain image quality without excessive complexity.

Inventive Principle:

Principle #1Segmentation

2Productivity

If efficiency is increased, then driving voltage decreases, but hole accumulation phenomenon worsens leading to capacitance increase

Engineering Contradiction:

Improveluminous efficiencyVSAvoidcharge transfer smoothness

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the capacitance parameter of the hole transport layer to less than 1 nF by selecting specific organic compounds with appropriate molecular structures and energy levels. This parameter optimization ensures efficient charge transfer at high luminous efficiency while preventing hole accumulation and maintaining image quality.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multi-layered structure is used to improve efficiency and stability, then material properties must be optimally combined, but material development complexity increases

Engineering Contradiction:

Improvedevice stabilityVSAvoidmaterial development difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by assigning specific functions to different layers: the first hole transport layer focuses on hole injection with specific capacitance <1 nF, the second layer on charge transport, and the third layer on interface management. Each layer uses materials optimized for its specific function, achieving high stability while making material selection more systematic and manageable.

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 achieves high luminous efficiency, low driving voltage, improved color purity, and extended lifespan by ensuring smooth charge injection and reducing undesirable light emission.

Implementation Method 1

the capacitance of the OLED device changes according to this internal charge movement. At this time, if a hole accumulation phenomenon occurs in which holes do not move smoothly and holes continue to accumulate in the hole transport layer, the capacitance in the hole transport layer increases.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

organic light emitting phenomenon refers to a phenomenon that converts electric energy into light energy by using an organic material

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

A material used as an organic material layer in an organic electronic element may be classified into a light emitting material and a charge transport material, such as a hole injection material, a hole transport material, an electron transport material, an electron injection material etc. depending on its function.

Methodology Applied

Scientific EffectCharge transport: Conduction (electrical)

Data Source

PatentEP4727310A1Organic electric element comprising compound for organic electric element, and electronic device therefor

Publication Date: 2026.04.15 DUK SAN NEOLUX

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AI summary

The present invention provides an organic electric element including a first electrode, a second electrode, and at least one organic material layer between the first electrode and the second electrode, and an electronic element including same. The organic material layer includes a hole transport region, an emitting layer, and an electron transport region, wherein the hole transport layer comprises a compound having a capacitance of less than 1 nF in a range of 0 V to 1 V as measured for capacitance-voltage at 120 Hz and ±0.1 V, thereby lowering a driving voltage of the organic electronic element and improving luminous efficiency and lifespan.