OLED Emissive Layer with Delayed Fluorescent and BODIPY Materials
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional organic light emitting diodes (OLEDs) face limitations in luminous efficiency, color purity, and luminous lifespan, particularly due to the short lifespan of phosphorescent materials and the low efficiency of fluorescent materials that only utilize singlet excitons.
Innovation Solution
An OLED structure is developed with an emissive layer containing specific compounds, including delayed fluorescent materials and fluorescent materials, which have adjusted energy levels to efficiently transfer and utilize both singlet and triplet excitons, enhancing luminous efficiency and color purity through the use of compounds like those described in Formulas 1, 3, and 5, and their combinations in single or multiple emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phosphorescent materials are used to improve luminous efficiency, then triplet excitons are utilized, but luminous lifespan becomes too short
Solution Approach 1:
The emitting layer is divided into multiple layers with different functions: a first emitting layer containing phosphorescent material for triplet exciton utilization, and a second emitting layer containing fluorescent material for singlet exciton emission. This segmentation allows each layer to perform its specialized function while working together to achieve both high efficiency and long lifespan.
Solution Approach 2:
A charge blocking layer is introduced as an intermediary between the phosphorescent and fluorescent emitting layers. This layer controls charge carrier distribution, preventing excessive charge accumulation in the phosphorescent layer that would cause degradation, while still allowing efficient exciton formation. The charge blocking layer mediates the interaction between the two emitting materials to achieve stable long-term operation.
2Duration of action of stationary object
If fluorescent materials are used to maintain long luminous lifespan, then only singlet excitons are utilized, but luminous efficiency becomes low
Solution Approach 1:
The emitting layer is divided into multiple layers with different functions: a first emitting layer containing phosphorescent material for triplet exciton utilization, and a second emitting layer containing fluorescent material for singlet exciton emission. This segmentation allows each layer to perform its specialized function while working together to achieve both high efficiency and long lifespan.
Solution Approach 2:
The device uses a composite structure combining phosphorescent and fluorescent materials in separate emitting layers. Each material type contributes its strengths: phosphorescent material provides high efficiency through triplet exciton utilization, while fluorescent material provides long lifespan and stability. The composite structure achieves performance superior to either material alone.
3Device complexity
If a single emitting layer is used to simplify device structure, then material selection is limited, but it is difficult to achieve both high efficiency and long lifespan simultaneously
Solution Approach 1:
The emitting layer is divided into multiple layers with different functions: a first emitting layer containing phosphorescent material for triplet exciton utilization, and a second emitting layer containing fluorescent material for singlet exciton emission. This segmentation allows each layer to perform its specialized function while working together to achieve both high efficiency and long lifespan.
Solution Approach 2:
The multi-layer emitting structure serves multiple functions simultaneously: the phosphorescent layer captures triplet excitons for high efficiency, the fluorescent layer ensures long lifespan and color purity, and the charge blocking layer manages charge distribution. This multi-functional design achieves comprehensive performance improvement without requiring separate devices for different functions.
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 OLED structure significantly improves luminous efficiency and color purity by effectively utilizing both singlet and triplet excitons, leading to enhanced internal quantum efficiency and extended luminous lifespan, surpassing the limitations of conventional materials.
Implementation Method 1
the at least one emitting material layer includes a first compound, a second compound and a third compound... the first compound has the following structure of Formula 1... the second compound has the following structure of Formula 3 and the third compound has the following structure of Formula 5
Implementation Method 2
The phosphorescent materials in which triplet excitons as well as the singlet excitons are involved in the luminescence process have relatively high luminous efficiency
Implementation Method 3
when electrical charges are injected into an emitting material layer between an electron injection electrode (i.e., cathode) and a hole injection electrode (i.e., anode), electrical charges are recombined to form excitons, and then emit light as the recombined excitons are shifted to a stable ground state
Data Source
AI summary
An organic light emitting diode (OLED) including at least one emitting material layer (EML) disposed between two electrodes and including plural delayed fluorescent materials having at least one carbazolyl moiety and BODIPY-based fluorescent material and an organic light emitting device including the OLED are discussed. The delayed fluorescent material and the fluorescent material can be included in the same emitting material layer or adjacently disposed emitting material layers. The OLED can lower its driving voltage and improve its luminous efficiency utilizing the advantages of the delayed fluorescent materials and the fluorescent material by adjusting energy levels among the delayed fluorescent materials and the fluorescent material.