OLED Emitter Layer Using Delayed Fluorescent Compounds
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Solution Overview
Problem
Conventional organic light emitting diodes (OLEDs) face limitations in driving voltage, emitting efficiency, and lifespan, particularly due to the low efficiency of fluorescent compounds used as dopants in the emitting material layer.
Innovation Solution
Incorporating a specific combination of delayed fluorescent compounds and a fluorescent compound in the emitting material layer, represented by defined chemical formulas, to enhance the energy transfer efficiency and reduce driving voltage while improving the lifespan and efficiency of the OLED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a fluorescent compound is used as a dopant in the emitting material layer, then color purity is improved, but emitting efficiency deteriorates
Solution Approach 1:
The patent employs a composite emitting material layer containing both fluorescent compound and delayed fluorescent compound. The fluorescent compound (e.g., Bpy-OXDQ) provides narrow FWHM for high color purity, while the delayed fluorescent compound (e.g., TCTA or TAPC) contributes to enhanced emitting efficiency through triplet exciton utilization. This composite approach allows simultaneous achievement of color purity and emitting efficiency that cannot be obtained with either compound alone.
Solution Approach 2:
The patent optimizes the weight ratios of fluorescent compound to delayed fluorescent compound in the emitting material layer. By adjusting these compositional parameters, the device achieves optimal balance between color purity (determined by fluorescent compound content) and emitting efficiency (enhanced by delayed fluorescent compound). Specific weight ratios are established to maximize both parameters simultaneously.
2Device complexity
If conventional fluorescent compounds are used in the emitting material layer, then device structure is simplified, but driving voltage increases and lifespan decreases
Solution Approach 1:
The emitting material layer uses a composite system of fluorescent and delayed fluorescent compounds to achieve both simplified structure and improved reliability. The delayed fluorescent compound component specifically addresses lifespan extension by enabling more efficient exciton utilization, reducing degradation mechanisms while maintaining structural simplicity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the emitting material layer by introducing delayed fluorescent compounds with specific molecular structures and energy levels. These parameter changes lead to reduced driving voltage and extended operational lifespan without complicating the overall device architecture.
3Ease of manufacture
If conventional fluorescent compounds are used as dopants, then manufacturing process is simplified, but emitting efficiency decreases
Solution Approach 1:
The patent implements a composite emitting material layer that combines fluorescent and delayed fluorescent compounds. This composite approach enhances emitting efficiency through triplet exciton harvesting by the delayed fluorescent compound, while the fabrication process remains relatively simple as both compounds can be co-deposited or solution-processed using conventional OLED manufacturing techniques.
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 proposed solution significantly decreases the driving voltage and increases the emitting efficiency and lifespan of the OLED by optimizing the energy transfer within the emitting material layer, leading to improved performance in OLED devices.
Implementation Method 1
The OLED emits light by injecting electrons from a cathode as an electron injection electrode and holes from an anode as a hole injection electrode into an emitting material layer (EML), combining the electrons with the holes, generating an exciton, and transforming the exciton from an excited state to a ground state.
Implementation Method 2
A fluorescent compound among dopant compounds has a narrow full width at half maximum (FWHM) to provide a high color purity. The first emitting part includes a first delayed fluorescent compound, a second delayed fluorescent compound, and a first fluorescent compound.
Data Source
AI summary
The present disclosure relates to an organic light emitting diode comprising a first electrode; a second electrode facing the first electrode; and a first emitting part including a first red emitting material layer and positioned between the first and second electrode, the first red emitting material layer including a first delayed fluorescent compound, a second delayed fluorescent compound and a first fluorescent compound, wherein the first delayed fluorescent compound is represented by Formula 1, the second delayed fluorescent compound is represented by Formula 3, and the first fluorescent compound is represented by Formula 5.