OLED Electron Adjusting Layer for Efficiency and Lifespan
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Solution Overview
Problem
Existing organic light emitting diodes (OLEDs) face challenges in achieving high light emitting efficiency and long service life, particularly those emitting blue fluorescent light, which experience reduced lifespan due to high exciton energy concentration.
Innovation Solution
Incorporating an electron adjusting layer with a heterocyclic compound represented by Formula 1 between the light emitting layer and the electron transporting layer, and using an organic compound with an aromatic hetero ring in the electron transporting layer, where the ionization potential of the electron transporting layer is higher than that of the electron adjusting layer, to control electron mobility and prevent hole migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blue fluorescent light emitting material is used in OLED, then light emitting efficiency is improved, but service life is reduced due to high exciton energy concentration
Solution Approach 1:
An electron adjusting layer is introduced as an intermediary between the light emitting layer and electron transporting layer. This layer mediates the energy distribution by adjusting electron injection, preventing excessive exciton energy concentration in the blue fluorescent material, thereby maintaining high efficiency while extending device lifetime
Solution Approach 2:
The ionization potential parameter is optimized by selecting specific materials for the electron adjusting layer (with ionization potential between 5.8-6.5 eV) and electron transporting layer (with ionization potential 6.0-6.8 eV). This parameter control enables precise regulation of electron and hole balance, reducing exciton energy concentration while preserving light emitting efficiency
2Reliability
If electron transporting layer with high ionization potential is used, then electron mobility is improved and hole migration is prevented, but device complexity increases
Solution Approach 1:
The electron transporting function is segmented into two distinct layers: an electron adjusting layer and an electron transporting layer. This segmentation allows each layer to be optimized for its specific function while working together to achieve overall electron mobility control and hole migration prevention
Solution Approach 2:
The electron adjusting layer serves multiple functions simultaneously: it adjusts electron mobility, prevents hole migration into the electron transporting layer, and maintains energy level alignment. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity
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 configuration results in low driving voltage, high efficiency, and extended service life for the OLEDs, maintaining efficiency and lifespan across various color coordinates.
Implementation Method 1
an ionization potential (Ip m ) of the electron transporting layer is larger than an ionization potential (IP a ) of the electron adjusting layer
Implementation Method 2
electrons and holes are injected from the negative electrode and the positive electrode, respectively, into the organic material layer. The electrons and the holes which are injected into the organic material layer are recombined to form an exciton, and the exciton falls down again to the ground state to emit light
Data Source
Figure 1
AI summary
The present specification relates to an organic light emitting diode.