Organic Electroluminescent Display Mixed Electron Transport Layer
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Solution Overview
Problem
Organic electroluminescent display devices face reduced service life due to mismatched mobilities and energy levels between hole and electron transport layers, leading to premature degradation and reduced efficiency.
Innovation Solution
Incorporating a mixed electron transport layer with a hole blocking capability and optimizing the thickness and composition of the electron transport emission layer to enhance electron mobility and prevent premature hole-electron collisions, allowing for improved exciton formation in the emission layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional electron transport layer is used, then the device structure is simple, but the service life is reduced due to premature hole-electron collisions and degraded electron transport function
Solution Approach 1:
The electron transport function is segmented into two distinct layers: a first electron transport layer adjacent to the emission layer with electron mobility ≥10^-6 cm²/Vs, and a second electron transport layer adjacent to the electron injection layer with electron mobility ≥10^-5 cm²/Vs. This segmentation allows each layer to be optimized for its specific function, preventing premature hole-electron collisions and extending device service life while maintaining structural organization.
Solution Approach 2:
Different electron mobility characteristics are assigned to different regions of the electron transport system. The first electron transport layer uses materials with lower electron mobility (≥10^-6 cm²/Vs) to control exciton formation location, while the second electron transport layer uses materials with higher electron mobility (≥10^-5 cm²/Vs) for efficient electron injection. This local quality differentiation resolves the contradiction between structural simplicity and service life extension.
2Productivity
If the emission layer uses organic material with high hole mobility, then hole transport is efficient, but electrons and holes collide near the electron transport layer interface reducing device lifetime
Solution Approach 1:
The first electron transport layer acts as an intermediary between the emission layer and the second electron transport layer. It controls the location of exciton formation through its specific electron mobility characteristics, preventing direct collision between holes and electrons at the interface with the second electron transport layer. This intermediary layer maintains efficient hole transport while protecting device lifetime by controlling where recombination occurs.
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 extends the service life of organic electroluminescent display devices by ensuring effective electron transport and maintaining emission efficiency, with a 110-hour increase in '97% lifetime characteristics compared to previous designs.
Implementation Method 1
The organic electroluminescent display device emits the light by forming exiton when the hole generated at the anode electrode and the electron generated at the cathode electrode are jointed at the emission layer
Data Source
Figure 1
Figure 2A~2B
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AI summary
The present disclosure relates to an organic electroluminescent display device. The organic electroluminescent display device according to an embodiment of the present disclosure comprises: a substrate including thin film transistor; a first electrode disposing on the substrate and connecting to the thin film transistor; an electron transport emission layer on the first electrode; and a second electrode on the electron transport emission layer; wherein the electron transport emission layer includes an electron transport material and an emission material.