Organic EL Charge-Generating Layer for Leakage Suppression
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Solution Overview
Problem
Conventional organic electroluminescence (EL) devices face challenges in maintaining high luminous efficiency and low driving voltage while preventing current leakage between pixels, particularly due to the use of inorganic substances that require high deposition temperatures and transparent conductors that can cause color mixing and reduced color reproducibility.
Innovation Solution
A stacked-type organic EL device is designed with a charge-generating layer comprising a specific compound represented by formula (I), which includes an N layer near the anode and a P layer near the cathode, using organic compounds that allow for low deposition temperatures and reduced conductivity, thereby suppressing current leakage and enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic substances (metal oxides) are used in charge-generating layer, then electrical conductivity is improved, but deposition temperature increases and mass productivity decreases
Solution Approach 1:
The patent changes the material parameter from inorganic metal oxides to organic compounds, fundamentally altering the deposition temperature requirement from high (inorganic) to low (organic), thereby resolving the contradiction between conductivity and productivity
Solution Approach 2:
The patent substitutes inorganic materials with organic materials in the charge-generating layer, replacing the high-temperature deposition process with a low-temperature organic compound deposition process, achieving both good conductivity and high mass productivity
2Reliability
If transparent conductors (ITO) are used in charge-generating layer, then electrical conductivity is improved, but current leakage between pixels occurs and color purity decreases
Solution Approach 1:
The patent applies local quality by using organic compounds with appropriate conductivity for the charge-generating layer function while maintaining pixel isolation, achieving local optimization of electrical properties without the harmful current leakage effect of transparent conductors
Solution Approach 2:
The patent uses organic compounds that can be deposited at low temperatures and provide sufficient conductivity for charge generation without the persistent high conductivity of transparent conductors that causes current leakage, effectively replacing the problematic material
3Reliability
If transparent conductors are used in charge-generating layer, then electrical conductivity is improved, but color reproducibility deteriorates due to color mixing from adjacent pixel emission
Solution Approach 1:
The patent optimizes the electrical conductivity locally in the charge-generating layer using organic compounds, achieving sufficient charge injection while preventing the excessive conductivity that causes current leakage and color mixing, thereby maintaining color reproducibility
4Illumination intensity
If driving current is increased to increase initial luminance, then luminance is improved, but device life is shortened
Solution Approach 1:
The patent enables the organic EL device to achieve high luminance through improved luminous efficiency of the charge-generating layer, allowing the device to operate at lower currents while maintaining high brightness, thereby extending device life through self-optimized performance
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
The solution achieves high luminous efficiency and low driving voltage while preventing current leakage between pixels, improving color reproducibility by using the specified charge-generating layer compounds, which are formed at lower temperatures and have lower conductivity than traditional materials.
Implementation Method 1
the charge-generating layer, when a voltage is applied, serves to inject holes to an emitting unit arranged on the side of a charge-generating layer near to a cathode, and on the other hand, serves to inject electrons to an emitting unit arranged on the side of the charge-generating layer near to an anode
Implementation Method 2
the P layer serves to inject holes to an emitting unit arranged on the side of a charge-generating layer near to a cathode
Implementation Method 3
the N layer nearer to the anode and a P layer nearer to the cathode... serves to inject electrons to an emitting unit arranged on the side of the charge-generating layer near to an anode
Data Source
AI summary
An organic electroluminescence device including: an anode; a cathode; two or more emitting units that are disposed between the anode and the cathode, each unit having an emitting layer; and a charge-generating layer that is disposed between the emitting units, wherein the charge-generating layer comprises an N layer nearer to the anode and a P layer nearer to the cathode, and the P layer comprises a compound represented by the following formula (I).