Organic Electroluminescent Device with Hole Blocking Layer
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving balanced carrier transport, particularly in blue delayed fluorescent devices, where the mobility of electrons is lower than holes, leading to excess holes that reduce brightness and lifetime, and existing hole blocking materials are not effectively applicable across different phosphorescent devices.
Innovation Solution
A blue delayed fluorescent device with a hole blocking layer comprising a compound of specific structure, combined with a first and second host material in the emissive layer, and a light-emitting device comprising blue, green, and red phosphorescent units, all sharing a common hole blocking material to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a hole blocking layer is introduced to achieve carrier balance, then device lifetime is improved, but device complexity increases
Solution Approach 1:
The patent develops a hole blocking material with structure Formula (1) that can be universally applied across blue delayed fluorescent, green phosphorescent, and red phosphorescent devices. This multi-functional material resolves the contradiction by providing carrier balance protection (improving lifetime) through a single material solution rather than requiring different materials for different device types, thereby avoiding increased complexity.
2Reliability
If different hole blocking materials are used for blue delayed fluorescent, green phosphorescent, and red phosphorescent devices, then each device achieves optimal performance, but material types and device complexity increase
Solution Approach 1:
The patent creates a universal hole blocking material with structure Formula (1) that can be applied to blue delayed fluorescent, green phosphorescent, and red phosphorescent devices. This single material structure replaces the need for multiple specialized materials, reducing material type complexity while maintaining reliable performance across all device types through its adaptable molecular design.
Solution Approach 2:
The patent employs parameter changes by modifying the substituent groups (R1, R2, X, Y1-Y8) in the hole blocking material structure Formula (1) to optimize performance across different device types. By adjusting these molecular parameters rather than using fundamentally different material structures, the patent achieves device-specific optimization without increasing the number of material types.
3Illumination intensity
If electrons and holes meet in the emissive layer to form excitons, then light emission is achieved, but excess holes accumulate and reduce device brightness
Solution Approach 1:
The patent introduces a hole blocking layer with material structure Formula (1) as an intermediary between the emissive layer and electron transporting layer. This intermediary selectively blocks excess holes while allowing electrons to pass, preventing harmful hole accumulation in the emissive layer and maintaining high device brightness through balanced carrier transport.
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 achieves improved overall device performance by balancing carrier transport, increasing efficiency, and extending the lifetime of the blue delayed fluorescent device, while also improving the performance of red and green phosphorescent devices by reducing material types and enhancing light-emitting performance.
Implementation Method 1
the hole blocking layer is an important functional layer that affects performance of the organic electroluminescent device
Implementation Method 2
Organic electroluminescent devices convert electrical energy into light by applying voltages across the devices
Implementation Method 3
a blue delayed fluorescent device comprising a hole blocking material having a structure of Formula 1 in a hole blocking layer and comprising a first host material, a second host material and a blue delayed fluorescent material in an emissive layer
Data Source
AI summary
Provided is an organic electroluminescent device. The organic electroluminescent device is a blue delayed fluorescent device including an anode, a cathode, an emissive layer disposed between the anode and the cathode and a hole blocking layer disposed between the emissive layer and the cathode, where the hole blocking layer comprises a hole blocking material having a structure of Formula 1, and the emissive layer comprises a first host material, a second host material and a blue delayed fluorescent material having a structure of Formula 3. The blue delayed fluorescent device exhibits excellent overall device performance, such as higher efficiency and longer lifetime. Further provided are a light-emitting device comprising a blue delayed fluorescent unit, a green phosphorescent unit and a red phosphorescent unit and a display assembly comprising the blue delayed fluorescent device and the light-emitting device.