Phosphorescent Organic EL Layer with 500–2000 Molecular Weight
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Solution Overview
Problem
Existing organic EL elements face challenges in achieving longer lifetimes, higher emission efficiency in high luminance regions, and improved reliability for practical use in displays and lighting applications.
Innovation Solution
A light-emitting element with a light-emitting layer containing a first organic compound, a second organic compound with electron-transport properties, and a phosphorescent compound, where the first organic compound has a molecular weight between 500 and 2000, and includes fluorene, spirofluorene, or biphenylene skeletons, and a carbazole skeleton, enhancing stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic EL elements are used, then basic light emission is achieved, but lifetime and emission efficiency in high luminance regions are insufficient
Solution Approach 1:
The patent employs composite materials by combining multiple organic compounds with specific molecular weight ranges (500-2000) in the light-emitting layer. This composite approach allows synergistic effects between different compounds, improving both lifetime and high-luminance emission efficiency while maintaining stable electrical and optical properties.
Solution Approach 2:
The patent systematically optimizes molecular weight parameters of organic compounds within specific ranges (500-2000) to achieve optimal balance between lifetime, emission efficiency, and stability. By controlling molecular weight as a key parameter, the invention resolves the contradiction between durability and performance under high luminance conditions.
2Illumination intensity
If organic compounds with high emission efficiency are used, then light output is improved, but stability and lifetime are reduced
Solution Approach 1:
The patent changes the molecular weight parameter of organic compounds to fall within the specific range of 500-2000, which optimizes the balance between emission efficiency and stability. This parameter control ensures that compounds maintain high light output while exhibiting improved temporal and environmental stability.
Solution Approach 2:
The patent applies local quality by selecting organic compounds with specific structural characteristics (certain molecular weight ranges) for specific functional roles in the light-emitting layer. This targeted selection ensures that high emission efficiency is achieved in the light-emitting function while stability is enhanced through appropriate molecular structure selection.
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 results in a light-emitting element with a long lifetime, high emission efficiency in high luminance regions, and improved reliability, leading to high-performance light-emitting, electronic, and lighting devices.
Implementation Method 1
light emission from the triplet excited state (T*) is referred to as phosphorescence
Implementation Method 2
EL elements can be broadly classified according to whether the light-emitting substance is an organic compound or an inorganic compound. In the case of an organic EL element in which a layer containing an organic compound as the light-emitting substance is provided between a pair of electrodes, application of a voltage to the light-emitting element causes injection of electrons from the cathode and holes from the anode into the layer containing the organic compound, and thus a current flows. The injected electrons and holes then lead the organic compound to its excited state, whereby light emission is obtained from the excited organic compound.
Data Source
AI summary
A light-emitting element having a long lifetime is provided. A light-emitting element exhibiting high emission efficiency in a high luminance region is provided. A light-emitting element includes a light-emitting layer between a pair of electrodes. The light-emitting layer contains a first organic compound, a second organic compound, and a phosphorescent compound. The first organic compound is represented by a general formula (G0). The molecular weight of the first organic compound is greater than or equal to 500 and less than or equal to 2000. The second organic compound is a compound having an electron-transport property. In the general formula (G0), Ar1 and Ar2 each independently represent a fluorenyl group, a spirofluorenyl group, or a biphenyl group, and Ar3 represents a substituent including a carbazole skeleton.