OLED Emitter Layer Dopant Ratio for Color Continuity
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Solution Overview
Problem
Current organic light emitting diodes (OLEDs) face challenges in achieving high color continuity and emitting efficiency, particularly in white-OLEDs, due to the lack of a red emitting material with a narrow full width at half maximum (FWHM) and the need for a combination of red, green, and blue emitting materials.
Innovation Solution
An OLED structure is developed with a first emitting material layer containing a delayed fluorescent dopant and a phosphorescent dopant, where the percentage by weight of the phosphorescent dopant is equal to or less than 5, allowing for both dopants to contribute to light emission, thereby enhancing color continuity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a red delayed fluorescent material with wide FWHM is used to provide high color continuity, then the color continuity is improved, but the emitting efficiency deteriorates
Solution Approach 1:
The patent combines a delayed fluorescent material (DF) with a phosphorescent material (Ph) in the emitting material layer. The DF material provides broad emission spectrum for color continuity, while the Ph material enhances emitting efficiency through phosphorescent emission. This merging of two different luminescent mechanisms resolves the contradiction between color continuity and emitting efficiency.
Solution Approach 2:
The emitting material layer uses a composite system consisting of delayed fluorescent dopant and phosphorescent dopant together with a host material. This composite material approach allows the system to simultaneously achieve the broad emission characteristics of DF materials and the high efficiency of phosphorescent materials, resolving the trade-off between color continuity and emitting efficiency.
2Stability of the object's composition
If a white-OLED structure with multiple emitting materials is used to achieve high color continuity, then the color continuity is improved, but the device complexity increases
Solution Approach 1:
The patent merges the functions of multiple emitting materials into a single emitting material layer by combining delayed fluorescent and phosphorescent dopants. This approach achieves the color continuity benefits of multi-material systems while maintaining a relatively simple single-layer structure, thus reducing device complexity compared to traditional multi-layer white-OLED structures.
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 OLED achieves improved color continuity and high emitting efficiency by ensuring that both the delayed fluorescent and phosphorescent dopants are involved in light emission, meeting the requirements for both lighting and display devices with specific color temperature conditions.
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 first emitting material layer including a first delayed fluorescent dopant and a first phosphorescent dopant
Implementation Method 3
a first emitting material layer including a first delayed fluorescent dopant and a first phosphorescent dopant
Data Source
AI summary
An embodiment of the present disclosure provides an organic light emitting diode comprising a first electrode; a second electrode facing the first electrode; and a first emitting material layer including a first delayed fluorescent dopant and a first phosphorescent dopant and disposed between the first and second electrodes, wherein a percentage by weight of the first phosphorescent dopant with respect to the first delayed fluorescent dopant is equal to or less than 5.