OLED Charge Generation Layer Energy Bandgap Control
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Solution Overview
Problem
Existing organic light emitting diodes (OLEDs) face challenges in achieving balanced charge injection and efficient color compensation, leading to reduced luminous efficiency and unstable white balance due to the use of fluorescent materials and short luminous lifespan of metal complexes.
Innovation Solution
The implementation of an OLED structure with a charge generation layer having a specific energy bandgap between the P-type host and dopant, allowing for balanced charge injection and improved luminous efficiency, and the use of multiple emitting parts with different materials to achieve efficient color compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent material (metal complex) is used to improve luminous efficiency by utilizing triplet exciton energy, then luminous efficiency is improved, but luminous lifespan becomes short
Solution Approach 1:
The emissive layer is divided into multiple emitting parts (first emitting part with first luminous material, second emitting part with second luminous material) having different emission peaks. This segmentation allows different materials to contribute differently to the overall emission, enabling efficient utilization of exciton energy while maintaining stable white balance and extended lifespan by avoiding over-reliance on short-lived phosphorescent materials.
2Use of energy by moving object
If multiple luminous materials with different emission peaks are used to implement white emission, then luminous efficiency is improved, but white balance becomes unstable
Solution Approach 1:
The patent carefully selects and adjusts parameters of the luminous materials including emission peaks (first emission peak and second emission peak), exciton energy utilization, and material composition ratios. By optimizing these parameters, the device achieves stable white balance while maintaining high luminous efficiency through efficient energy utilization of multiple emitting parts.
3Duration of action of stationary object
If fluorescent material is used to simplify the structure and avoid short lifespan issues, then luminous lifespan is extended, but luminous efficiency decreases due to underutilization of triplet exciton energy
Solution Approach 1:
The patent employs composite material strategy by combining multiple luminous materials (including at least one phosphorescent material and at least one fluorescent or delayed fluorescent material) in the emissive layer. This composite approach enables the system to utilize both singlet and triplet exciton energies efficiently while maintaining stable white balance and extended operational lifespan through the complementary characteristics of different materials.
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 enhances luminous efficiency, extends the luminous lifespan, and maintains stable white balance by ensuring balanced charge injection and efficient color compensation across varying gradations and current densities.
Implementation Method 1
an energy bandgap between a Highest Occupied Molecular Orbital (HOMO) energy level of the P-type host and a Lowest Unoccupied Molecular Orbital (LUMO) energy level of the P-type dopant satisfies a relationship of the following Formula A: 0.35 eV≤LUMOD−HOMOH≤0.5 eV
Implementation Method 2
the multiple emitting parts include at least one emitting part comprising a green emitting material layer
Implementation Method 3
phosphorescent material can show high luminous efficiency since it uses triplet exciton energy as well as singlet exciton energy in the luminous process
Implementation Method 4
fluorescent material uses only singlet exciton energy in the luminous process
Data Source
AI summary
The present disclosure relates to an organic light emitting diode and an organic light emitting device including thereof. The organic light emitting diode (OLED) includes multiple emitting parts disposed between two facing electrodes and at least one charge generation layer disposed between the multiple emitting parts. The at least one of the multiple emitting parts includes a green emitting material layer, and an energy bandgap between HOMO energy level of host and LUMO energy level of dopant in a P-type charge generation layer is controlled. The OLED and the organic light emitting device can improve their luminous efficiency by controlling charge injections in an emissive layer and improve efficiently white balance by suitable color compensation.