Tandem White OLED With Hole Transport Host Optimization
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Solution Overview
Problem
Current organic light emitting diodes (OLEDs) face challenges in achieving a long lifespan and low driving voltage, which are crucial for developing efficient and low-power displays with improved luminous efficacy and color quality.
Innovation Solution
A tandem white organic light emitting diode structure is introduced, featuring a first blue light emitting layer, a charge generation layer, a second light emitting part with red and yellow-green light emitting layers, and a third blue light emitting layer, where the proportions of hole transport hosts and dopants in these layers are carefully controlled to optimize charge balance and recombination regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a white organic light emitting diode with multi stack structure is used, then luminous efficacy and color quality are improved, but lifespan and driving voltage control become challenging
Solution Approach 1:
The white OLED is divided into multiple light emitting stacks, each containing specific light emitting layers (blue, green, red) with optimized material compositions. Each stack independently contributes to the overall white light output, allowing separate optimization of luminous efficacy and lifespan for different color components while maintaining system reliability.
2Illumination intensity
If multi stack structure with multiple light emitting layers is implemented, then color quality and luminous efficacy improve, but device complexity increases
Solution Approach 1:
Multiple light emitting layers (blue, green, red) are merged into integrated light emitting stacks where layers are closely coupled with shared charge transport layers. This merging approach achieves high color quality through combined emission while reducing structural complexity compared to completely separate emitter designs, as the stacks share common electrode and transport layer infrastructure.
3Productivity
If optimized material proportions are used in light emitting layers, then charge balance and recombination efficiency improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise weight ratio ranges for host and dopant materials in each light emitting layer (e.g., blue: 95-5 wt%, green: 90-10 wt%, red: 85-15 wt%). By defining optimized parameter ranges rather than single values, the invention achieves high recombination efficiency while providing manufacturing flexibility within specified bounds, balancing performance with manufacturability.
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 significantly enhances the lifespan and luminous efficacy of the OLED, reducing driving voltage and improving color quality by optimizing hole and electron transport, as demonstrated by increased brightness lifespan and reduced power consumption.
Implementation Method 1
a first light emitting part disposed on a first electrode and including a first blue light emitting layer
Data Source
AI summary
Disclosed are a tandem white organic light emitting diode with long lifespan and low driving voltage, and a display device including the same. The white organic light emitting diode includes a first light emitting part, a second light emitting part and a third light emitting part disposed between a first electrode and a second electrode. The first and third light emitting parts include a blue light emitting layer and the second light emitting part includes a red light emitting layer and a yellow-green light emitting layer. At least one layer of the red light emitting layer and the yellow-green light emitting layer includes a hole transport host based on a compound shown below:wherein each of R1, R2, and R3 are independently selected from hydrogen, heavy hydrogen, a C5-C7 aromatic cyclic and C1-C6 heterocyclic group.