White OLED Monolayer via Electrospraying Domain Segmentation
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Solution Overview
Problem
Monolayer type white OLEDs have relatively low light-emitting efficiency and short lifetime compared to stacking type white OLEDs, due to their simple device structure and manufacturing process.
Innovation Solution
A method of manufacturing a white OLED with a white light-emitting monolayer formed by electrospraying red, green, and blue ink layers onto a hole transport layer, using a specific ratio of light-emitting hosts and dopants, and an organic solvent with a dielectric constant between 5.5 and 18, to create distinct domains that prevent energy movement between dopants, thereby increasing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a monolayer type white OLED is used to simplify the device structure and manufacturing process, then the manufacturing cost is reduced, but the light-emitting efficiency and lifetime are lowered
Solution Approach 1:
The light-emitting layer is segmented into multiple independent domains, each containing a single dopant type (red, green, or blue). These domains are spatially separated and do not contact each other before reaching the substrate, preventing energy migration between different dopant types. This segmentation allows the monolayer structure to achieve stacking-type performance by isolating energy pathways while maintaining manufacturing simplicity.
Solution Approach 2:
Different regions of the light-emitting layer are assigned different local qualities by placing specific dopants (red, green, or blue) in distinct domains. Each domain has tailored energy characteristics suitable for its specific dopant, preventing unwanted energy transfer. This local quality differentiation enables the monolayer to achieve the efficiency of stacked structures while maintaining a single-layer architecture.
2Reliability
If multiple light-emitting layers are stacked to improve light-emitting efficiency and lifetime, then the performance is enhanced, but the device structure and manufacturing process become complicated
Solution Approach 1:
Multiple light-emitting layers that would traditionally be stacked are merged into a single monolayer light-emitting layer. Within this unified layer, distinct domains are created for each color (red, green, blue), but they remain part of the same continuous layer rather than separate stacked layers. This merging simplifies the device structure while maintaining the performance benefits of multiple layers through domain isolation.
Solution Approach 2:
Instead of stacking layers in the vertical dimension (creating multiple layers stacked on top of each other), the invention transitions to a horizontal dimension approach by creating multiple domains within a single layer. The domains are distributed laterally across the substrate surface, converting a vertical stacking problem into a horizontal domain distribution solution, thereby reducing structural complexity.
3Ease of manufacture
If dopants are mixed together in the light-emitting layer, then the manufacturing process is simplified, but energy movement between dopants reduces light-emitting efficiency
Solution Approach 1:
The light-emitting layer is segmented into multiple independent domains, each containing a single dopant type (red, green, or blue). These domains are spatially separated and do not contact each other before reaching the substrate, preventing energy migration between different dopant types. This segmentation allows the monolayer structure to achieve stacking-type performance by isolating energy pathways while maintaining manufacturing simplicity.
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 method enhances the light-emitting efficiency and extends the lifetime of the white OLED by forming a monolayer with electrosprayed domains, allowing for a simpler manufacturing process while maintaining high performance.
Implementation Method 1
forming the white light-emitting layer as a monolayer on the hole transport layer by separately electrospraying the red ink, the green ink, and the blue ink on the hole transport layer
Implementation Method 2
an organic solvent with a dielectric constant between 5.5 and 18
Data Source
AI summary
A method of manufacturing a white organic light-emitting device (white OLED) including a first electrode, a hole transport layer, a white light-emitting layer, an electron transport layer, and a second electrode which are sequentially formed on a substrate, the method including manufacturing a red ink by mixing a red light-emitting host and a red light-emitting dopant, manufacturing a green ink by mixing a green light-emitting host and a green light-emitting dopant, manufacturing a blue ink by mixing a blue light-emitting host and a blue light-emitting dopant, and forming a white light-emitting layer as a monolayer on the hole transport layer by separately electrospraying the red ink, the green ink, and the blue ink on the hole transport layer, wherein the white light-emitting layer includes a plurality of red light-emitting domains, a plurality of green light-emitting domains, and a plurality of blue light-emitting domains on the hole transport layer.