Organic Electroluminescent Device Electron Buffer Layer
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving high efficiency and long lifespan due to issues with color purity, electron transport, and stability, particularly with materials like Alq3 and fluorescent materials, which suffer from reduced efficiency and shortened lifespan.
Innovation Solution
An organic electroluminescent device is designed with a specific combination of an electron buffer layer and an electron transport layer, where the electron buffer layer comprises a compound represented by a particular formula and the electron transport layer comprises another compound, optimizing the LUMO energy levels to enhance electron injection and recombination, thereby improving efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Alq3 is used as electron transport material, then electron transport efficiency is improved, but color purity deteriorates due to material migration to other layers
Solution Approach 1:
The patent extracts Alq3 from the electron transport layer and relocates it to the electron buffer layer, separating its function from the electron transport function. This extraction resolves the contradiction by maintaining Alq3's electron transport capability in the buffer layer while preventing its migration-induced color purity loss in the electron transport layer, where alternative materials like BCP or Alq are used instead.
Solution Approach 2:
The patent segments the electron transport function across multiple layers: the electron buffer layer (containing Alq3) handles electron injection and initial transport, while the electron transport layer (containing BCP or Alq) handles bulk electron transport. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between electron transport efficiency and color purity.
2Device complexity
If fluorescent materials are used in light-emitting layer, then device structure is simplified, but efficiency deteriorates compared to phosphorescent materials
Solution Approach 1:
The patent introduces an electron buffer layer as an intermediary between the light-emitting layer and electron transport layer. This intermediary layer optimizes electron injection into the light-emitting layer, improving the efficiency of fluorescent materials by ensuring adequate electron supply for recombination, thereby reducing the efficiency gap with phosphorescent materials while maintaining structural simplicity.
3Productivity
If electron buffer layer is added to improve efficiency, then luminous efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the electron buffer layer with the electron transport layer in terms of material composition, using the same materials (Alq3, BCP, or Alq) in both layers. This merging approach minimizes the increase in device complexity by reusing established materials and fabrication processes, while still achieving improved luminous efficiency through the optimized energy level alignment and electron injection control provided by the dedicated electron buffer layer.
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 proposed device achieves high efficiency and long lifespan by optimizing electron injection and recombination, with the electron buffer layer controlling electron flow and the electron transport layer ensuring rapid electron transport, leading to improved luminous efficiency and extended device lifespan.
Implementation Method 1
an electron buffer layer and an electron transport layer, wherein the electron buffer layer comprises a compound of formula (1) and the electron transport layer comprises a compound of formula (2)... the electron buffer layer controlling electron flow and the electron transport layer ensuring rapid electron transport
Implementation Method 2
An organic EL device changes electric energy into light by the injection of a charge into an organic light-emitting material... The organic light-emitting compound moves into an excited state by the energy and emits light from energy when the organic light-emitting compound returns to the ground state from the excited state
Implementation Method 3
holes from an anode and electrons from a cathode are injected into a light-emitting layer by electric voltage, and an exciton having high energy is produced by the recombination of the holes and electrons
Data Source
AI summary
The present disclosure relates to an organic electroluminescent device. The organic electroluminescent device of the present disclosure comprises a specific combination of an electron buffer material and an electron transport material which can provide high efficiency and/or long lifespan.