Organic EL Device Triplet Energy Confinement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Phosphorescent organic electroluminescence devices face challenges in achieving high efficiency and long device life due to triplet energy leakage and high driving voltage, particularly when using materials with excellent carrier-injecting and transporting properties.
Innovation Solution
Incorporating a benzimidazole compound with specific structural features in the emitting layer and adjacent layers to prevent triplet energy leakage, combined with a compound having a large triplet energy, enables a low-voltage, high-efficiency, and long-lived organic electroluminescence device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a material with excellent carrier-injecting properties and carrier-transporting properties is used, then the driving voltage is reduced, but the carrier balance in the emitting layer is deteriorated, leading to shortened device life
Solution Approach 1:
The patent applies local quality by using different materials with specific properties in different layers: the electron-transporting layer uses a benzimidazole compound with specific carrier-transporting properties, while the emitting layer uses a host material with high triplet energy. This localized material selection allows each layer to perform its specific function optimally without compromising overall device performance and longevity.
Solution Approach 2:
The patent employs composite materials by combining the benzimidazole compound (Formula A) as an electron-transporting material with a host material (Formula 1) having high triplet energy in the emitting layer. This composite approach creates a synergistic effect where the electron-transporting layer efficiently transports carriers while the emitting layer maintains carrier balance and prevents triplet energy leakage, thereby reducing driving voltage without sacrificing device life.
2Ease of manufacture
If a host material with small triplet energy is used in the emitting layer, then the device can be manufactured, but the triplet energy leaks to the electron-transporting layer, leading to low efficiency
Solution Approach 1:
The patent applies parameter changes by selecting a host material with specifically high triplet energy (greater than 2.7 eV) in Formula 1. This parameter selection ensures that the triplet energy of the host material is sufficiently high to confine the triplet excitons within the emitting layer, preventing energy leakage to the electron-transporting layer while maintaining ease of manufacture through well-established synthesis routes for compounds of Formula 1.
3Illumination intensity
If a phosphorescent dopant material is used, then the device achieves phosphorescence emission, but the triplet energy must be efficiently confined requiring a host material with larger triplet energy than the dopant
Solution Approach 1:
The patent applies parameter changes by establishing a clear triplet energy hierarchy: the host material (Formula 1) has triplet energy greater than 2.7 eV, while the phosphorescent dopant has lower triplet energy. This parameter differentiation ensures efficient triplet energy confinement from the dopant to the host, enabling strong phosphorescence emission while simplifying material selection through well-defined energy level requirements.
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 effectively reduces driving voltage and enhances device lifetime by confining triplet energy within the emitting layer, improving the overall performance of the organic electroluminescence device.
Implementation Method 1
an organic thin film layer that is in contact with the emitting layer on the cathode side comprises at least one benzimidazole compound... having excellent electron-injection/transportation properties
Implementation Method 2
it is possible to prevent triplet energy from leaking to the electron-transporting layer side, whereby a low-voltage, high-efficient and long-lived organic EL device can be obtained
Implementation Method 3
An organic electroluminescence device comprising two or more organic thin film layers including an emitting layer between an anode and a cathode
Data Source
AI summary
An organic electroluminescence device including two or more organic thin film layers including an emitting layer between an anode and a cathode,the emitting layer including at least one compound represented by the following formula (1), andan organic thin film layer that is in contact with the emitting layer on the cathode side comprising at least one benzimidazole compound represented by the following formula (A):