Organic Electroluminescence Device Carbazole Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic electroluminescence devices face challenges in maintaining high light emission efficiency and durability at high luminance, with changes in chromaticity and voltage rise due to heat generation and exciton densification, especially when driven at high luminance levels.
Innovation Solution
Incorporating a specific compound with a carbazole structure in the light emitting layer and a hydrocarbon compound with a condensed polycyclic structure adjacent to the light emitting layer on the cathode side, which helps stabilize the light emission position and reduce chemical reactions, thereby minimizing changes in chromaticity and voltage rise over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the device is driven at high luminance, then light emission intensity is improved, but chromaticity changes and voltage rises due to heat generation and exciton densification
Solution Approach 1:
The patent introduces a specific organic compound (Formula 1) as an intermediary material in the light emitting layer that mediates between the high luminance driving condition and chromaticity stability. This compound acts as a buffer that prevents direct harmful interactions between excitons and the host material, thereby maintaining chromaticity even at high luminance levels
Solution Approach 2:
The patent changes the chemical and physical parameters of the light emitting layer by incorporating the specific compound (Formula 1) with defined molecular structure and properties. This parameter change in material composition enables the device to maintain stable chromaticity under high luminance driving conditions by altering the exciton generation and recombination characteristics
2Illumination intensity
If the device is driven at high luminance, then light emission intensity is improved, but voltage rises over time due to heat generation and exciton densification
Solution Approach 1:
The specific compound (Formula 1) serves as an intermediary that reduces direct heat generation from exciton recombination. By modifying the energy transfer pathway, this compound acts as a buffer that prevents excessive heat buildup, thereby maintaining voltage stability during high luminance operation
Solution Approach 2:
The patent converts the potentially harmful effect of exciton densification and heat generation into a beneficial outcome. By using the specific compound (Formula 1), the exciton energy is channeled more efficiently into light emission rather than heat, thereby reducing voltage rise while maintaining high luminance output
3Use of energy by moving object
If phosphorescent light emitting materials are used, then light emission efficiency is improved, but durability decreases due to chemical reactions and degradation at high luminance
Solution Approach 1:
The specific compound (Formula 1) acts as a protective intermediary between the phosphorescent light emitting material and the harsh operating conditions. This compound shields the phosphorescent material from degradation by reducing direct exposure to high energy excitons and heat, thereby extending device durability while maintaining high light emission efficiency
Solution Approach 2:
The patent creates a composite light emitting layer by combining the phosphorescent light emitting material with the specific compound (Formula 1). This composite structure leverages the high efficiency of phosphorescent materials while the additional compound provides protective functions, resulting in a system that achieves both high efficiency and improved durability
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 excellent light emission efficiency and durability with reduced changes in chromaticity and voltage rise, even at high luminance levels, by stabilizing the light emission position and minimizing chemical reactions.
Implementation Method 1
utilize, for light emission, energy of the exciton generated as a result of recombination of electrons injected from a cathode and holes injected from an anode in the organic layer
Implementation Method 2
Improvention in the efficiency of devices has been recently made by using a phosphorescent light emitting material
Data Source
AI summary
Provided is an organic electroluminescence device including a pair of electrodes composed of an anode and a cathode, a light emitting layer between the electrodes and an organic layer which is adjacent to the light emitting layer between the light emitting layer and the cathode, on a substrate, and the light emitting layer contains at least one compound having a carbazole structure and the organic layer adjacent to the light emitting layer contains at least one hydrocarbon compound having a specific structure.