Organic Electroluminescent Element with Phosphorescence Material
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Solution Overview
Problem
Existing organic electroluminescence elements face challenges in achieving low driving voltage while maintaining high light emission efficiency, particularly when using phosphorescence emission materials, due to imbalanced carrier flow and reduced efficiency.
Innovation Solution
Incorporating a phosphorescence light emitting material with high electron-transportability, specifically a platinum complex compound containing a tetradentate ligand, in combination with nitrogen-containing heterocyclic derivatives, to improve electron flow and balance carrier concentrations within the light emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If highly electron-transporting materials are used in electron transporting layer, then driving voltage is reduced, but light emission efficiency deteriorates due to excessive electron injection and carrier imbalance
Solution Approach 1:
The patent changes the chemical structure parameters of the phosphorescence emission material by introducing electron-transporting moieties (such as triazine, pyrimidine, or pyridine rings) into the ligand structure of the platinum complex. This structural modification enables the emission material itself to transport electrons, balancing the carrier flow and resolving the contradiction between low driving voltage and high light emission efficiency.
2Illumination intensity
If phosphorescence emission materials are used in light emitting layer, then light emission is achieved, but carrier balance between electrons and holes becomes off-balance due to sluggish electron flow
Solution Approach 1:
The patent modifies the electron transport capability parameter of the phosphorescence emission material by incorporating electron-transporting heterocyclic rings into the ligand structure. This enables the material to simultaneously fulfill both light emission and electron transport functions, achieving carrier balance while maintaining phosphorescence emission.
Solution Approach 2:
The phosphorescence emission material is designed to perform multiple functions: it serves as both the light-emitting species (platinum complex) and the electron transport medium (through the electron-transporting ligand structure). This multi-functionality resolves the contradiction between achieving light emission and maintaining carrier balance.
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 reduces driving voltage and maintains high external quantum efficiency by enhancing electron flow and carrier balance, effectively addressing the efficiency issues associated with phosphorescence materials.
Implementation Method 1
an electron-transporting phosphorous light emitting material... phosphorescence light emitting material having high electron-transportability... when a phosphorescence light emitting material of a platinum complex compound containing a tetradentate ligand is used, high efficiency and a low driving voltage can be achieved
Implementation Method 2
at least one layer of the at least one organic layer contains at least one selected from nitrogen-containing heterocyclic derivatives... by using a phosphorescence light emitting material having high electron-transportability in combination with a high electron transporting material, the flow of electrons in a light emitting layer is increased
Data Source
Figure 1
AI summary
An organic electroluminescence element including at least one organic layer including a light emitting layer, between an anode and a cathode, wherein at least one layer of the at least one organic layer contains at least one selected from specific nitrogen-containing heterocyclic derivatives, and at least one layer of the at least one organic layer contains a specific electron-transporting phosphorous light emitting material.