OLED Charge Generation Layer for Voltage Reduction
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Solution Overview
Problem
Existing organic light emitting diode (OLED) devices face challenges in improving current characteristics and reducing driving voltage while maintaining high luminance.
Innovation Solution
The OLED device incorporates a charge-generation layer with a first layer having electron transport properties and a second layer with hole transport properties, both made of undoped materials, positioned between two light emitting units of different colors, facilitating efficient electron and hole transport and reducing voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OLED structure is used, then device simplicity is maintained, but current characteristics are insufficient and driving voltage is high
Solution Approach 1:
The charge generation layer is divided into two distinct layers: a first charge generation layer adjacent to the anode and a second charge generation layer adjacent to the cathode. This segmentation allows each layer to be optimized for specific charge carrier generation, improving overall device performance while managing voltage requirements
Solution Approach 2:
Each charge generation layer is positioned strategically to generate specific charge carriers at specific locations. The first layer generates holes near the anode, while the second layer generates electrons near the cathode, creating local charge carrier sources that improve current characteristics and reduce voltage drop across the device
2Productivity
If multiple charge generation layers are added, then current density and luminance are improved, but device complexity increases
Solution Approach 1:
Both the first and second charge generation layers use undoped materials that can transport both electrons and holes, making them multi-functional. This universality allows the device to achieve improved current density and luminance without requiring highly specialized materials for each layer, thereby limiting the increase in device complexity
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 configuration enhances current density and luminance while lowering the driving voltage, achieving improved performance comparable to comparative examples with similar efficiency and color coordinates.
Implementation Method 1
The first charge-generation layer may have an electron transport property
Implementation Method 2
the second charge-generation layer may have a hole transport property
Implementation Method 3
Electrons injected from one electrode may be combined with holes injected from another electrode in an emission layer to generate excitons, which release energy in the form of emitted light
Data Source
AI summary
An organic light emitting diode device including an anode, a cathode facing the anode, and a light emitting member between the anode and cathode, wherein the light emitting member includes at least two light emitting units displaying the same or different color as one another, and a charge-generation layer between the at least two light emitting units, the charge-generation layer including a first charge-generation layer and a second charge-generation layer that each include an undoped material, and wherein the first charge-generation layer has an ionization energy that is about the same as or less than an electron affinity of the second charge-generation layer.