Organic Electroluminescent Device Spacer Layer Wavelength Control
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Solution Overview
Problem
Conventional organic electroluminescent devices require changing the combination of donor and acceptor compounds to control emission wavelength, which is time-consuming and labor-intensive, with limited options for forming exciplexes, making it difficult to adjust desired color tones.
Innovation Solution
An organic electroluminescent device configuration with a donor layer, a spacer layer, and an acceptor layer, where the spacer layer's thickness controls the emission wavelength, allowing for high emission efficiency and varied color emission without changing the donor and acceptor compound combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the combination of donor and acceptor compounds is changed to control emission wavelength, then the emission wavelength can be adjusted, but the process becomes time-consuming and labor-intensive requiring repeated investigations and synthesis
Solution Approach 1:
The invention changes the physical parameter (distance/separation) between the donor and acceptor compounds instead of changing their chemical identities. By controlling the distance through layer thickness or spacer insertion, the emission wavelength can be tuned across a broad range without requiring synthesis of new compounds or repeated device fabrication, thus resolving the time and labor consumption issue.
2Adaptability or versatility
If the combination of donor and acceptor compounds is changed to achieve desired color tone, then emission wavelength can be adjusted, but the complexity of repeated investigations and synthesis increases
Solution Approach 1:
The invention simplifies the complexity by changing a physical parameter (distance) rather than chemical parameters (compound structure). This approach requires only simple adjustments in layer thickness or spacer dimensions during device fabrication, eliminating the need for complex compound synthesis investigations and reducing overall process complexity.
Solution Approach 2:
The invention introduces a spacer layer as an intermediary component between the donor and acceptor compounds. This spacer acts as a mediator that enables wavelength control through its thickness or material properties, avoiding the need to directly modify the donor or acceptor compounds themselves and their complex synthesis processes.
3Reliability
If donor and acceptor compounds are placed in the same layer to form exciplex, then exciplex formation is achieved, but the emission wavelength control options are limited
Solution Approach 1:
The invention segments the single layer structure into separate donor layer, acceptor layer, and optional spacer layer. This segmentation maintains exciplex formation reliability by keeping the compounds in close proximity through the spacer while enabling independent control of their separation distance, thus expanding the emission wavelength control range without compromising exciplex efficiency.
Solution Approach 2:
The invention transitions from a two-dimensional mixing approach (compounds in the same layer) to a three-dimensional layered structure with controlled separation. By introducing the vertical dimension through layer thickness and spacer distance, the system achieves both reliable exciplex formation and broad wavelength tunability that cannot be obtained through horizontal mixing alone.
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
Enables efficient delayed fluorescence and broad wavelength control through the spacer layer thickness, simplifying the process of achieving various color emissions and improving emission efficiency.
Implementation Method 1
the compounds are needed to be physically near to each other, and specifically, repeated investigations of obtaining or synthesizing a large variety of compounds, producing light-emitting devices under the conditions suitable for those compounds, and measuring the emission wavelength are needed
Implementation Method 2
a light-emitting material using an exciplex formed of a combination of an acceptor compound and a donor compound has a possibility that, by combining a suitable acceptor compound and a suitable donor compound, the energy difference ΔE st between an excited triplet energy level and an excited singlet energy level can be reduced
Data Source
Figure 1~2(b)
Figure 3~4
Figure 5~6
AI summary
An organic electroluminescent device having a donor layer containing a donor compound, a spacer layer containing a spacer compound, and an acceptor layer containing an acceptor compound in that order, wherein the donor compound and the acceptor compound are compounds to form an exciplex to radiate delayed fluorescence, and the excited triplet energy of the spacer compound is higher than the excited triplet energy of the exciplex, can be controlled to have different emission wavelengths not requiring change of the combination of the donor compound and the acceptor compound therein.