Cathode-Side Blue Stack Electron Transport for Light-Emitting Devices
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Solution Overview
Problem
Existing light emitting display devices face limitations in efficiency increase due to differences in emission color and emission mechanisms between stacks, leading to reduced reliability and stability when materials are changed to enhance efficiency.
Innovation Solution
A light emitting device with a configuration that includes a blue fluorescent stack adjacent to the cathode, featuring a first hole transport layer, electron-blocking layer, blue light emitting layer with a boron-based dopant, electron transport layer, and electron injection layer, optimized with a mixture of materials to improve electron injection and transport efficiency, thereby enhancing blue light emission and reducing driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plurality of stacks are used to improve efficiency, then light emission efficiency is improved, but reliability is lowered due to lack of stability consideration when changing materials
Solution Approach 1:
The patent changes the material composition parameters of the electron transport layer by incorporating both ZADN and ETM-07 in specific weight ratios (1:9 to 9:1), optimizing electron transport efficiency while maintaining device stability and reliability in multi-stack configurations
Solution Approach 2:
The patent uses a composite material system in the electron transport layer by combining ZADN and ETM-07 materials, creating a hybrid composition that leverages the complementary properties of both materials to achieve high efficiency while maintaining reliability across multiple stacks
2Productivity
If materials are changed to increase efficiency, then efficiency is improved, but reliability is lowered because there is no consideration for stability
Solution Approach 1:
The patent optimizes the weight ratio parameters of ZADN and ETM-07 in the electron transport layer, systematically adjusting the composition to achieve maximum efficiency while ensuring material stability and device reliability
Solution Approach 2:
The patent applies local quality optimization by specifically tailoring the electron transport layer composition (ZADN and ETM-07 mixture) in the blue fluorescent stack adjacent to the cathode, where electron injection and transport are most critical, thereby improving efficiency without compromising overall device stability
3Productivity
If the blue fluorescent stack is optimized for efficiency, then blue light emission efficiency is improved, but driving voltage increases
Solution Approach 1:
The patent changes the compositional parameters of the electron transport layer by incorporating ZADN and ETM-07 in optimized weight ratios, reducing energy barriers for electron transport and thereby lowering driving voltage while maintaining or improving blue light emission efficiency
Solution Approach 2:
The patent introduces ETM-07 as an intermediary material in the electron transport layer that facilitates smoother electron transport between the cathode and the blue light emitting layer, reducing energy barriers and driving voltage while maintaining high emission efficiency
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 efficiency, reduced driving voltage, and prolonged lifespan by facilitating triplet-triplet annihilation in the blue fluorescent stack, optimizing electron injection and transport, and utilizing a mixture of materials to minimize energy barriers and repulsive forces at the interface.
Implementation Method 1
facilitating triplet-triplet annihilation in the blue fluorescent stack
Implementation Method 2
blue fluorescent stack
Implementation Method 3
optimizing electron injection and transport
Implementation Method 4
facilitating triplet-triplet annihilation in the blue fluorescent stack, optimizing electron injection and transport
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Disclosed are a light emitting device and a light emitting display device that are capable of improving efficiency, driving voltage, and lifespan by varying the configuration of a layer adjacent to a blue light emitting layer in a blue fluorescent stack contacting a cathode. The light emitting device includes n (wherein n is a natural number of 2 or more) stacks between an anode and a cathode facing each other, wherein an nth stack contacting the cathode is a first blue stack, wherein the first blue stack includes a first hole transport layer, a first electron-blocking layer, a first blue light emitting layer containing a boron-based dopant having an emission peak of 430 nm to 480 nm, a first electron transport layer contacting the blue light emitting layer, and an electron injection layer having two sides contacting the first electron transport layer and the cathode, respectively, wherein the first electron transport layer contains a mixture of a first material of Formula 1 with a second material of Formula 2.