Layered Fluorescent Display Structure Inhibits Energy Transfer
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Solution Overview
Problem
Current display technologies face challenges in achieving high resolution and low power consumption due to issues like color mixing, high manufacturing costs, and inefficient energy use, particularly with the separate-patterning technique, which requires precise vapor deposition and results in shadowing and color bleeding between pixels.
Innovation Solution
A display device with a layered structure where a first fluorescent luminescent material emits light in one subpixel, a second fluorescent luminescent material emits light in another, and a third luminescent material emits light in a third subpixel, with a separation layer inhibiting Förster-type energy transfer between layers, allowing for linear deposition and reduced color mixing, thereby achieving higher resolutions and lower power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the separate-patterning technique is used to form light-emitting layers for each color, then light emission efficiency is improved, but manufacturing precision deteriorates due to color bleeding and shadow effects
Solution Approach 1:
The light-emitting layer is segmented into multiple sub-layers, each containing a specific luminescent material for a particular color. This segmentation allows each layer to be deposited independently with linear deposition, preventing color bleeding while maintaining high light emission efficiency. The bank structure further segments the deposition regions for different colors.
Solution Approach 2:
Different luminescent materials are placed in specific local regions corresponding to different subpixels (red, green, blue). Each region receives only the appropriate luminescent material through controlled linear deposition, ensuring color purity and preventing shadow effects while maintaining efficient light emission in each local area.
2Manufacturing precision
If the vapor deposition source is distanced from the substrate to achieve acute deposition angle for high resolution, then manufacturing precision is improved, but device complexity increases due to raised vacuum chamber height
Solution Approach 1:
Instead of raising the vapor deposition source to achieve an acute deposition angle, the patent inverts the approach by lowering the substrate (TFT substrate) relative to the vapor deposition source. This maintains the acute deposition angle necessary for high-resolution patterning while avoiding the complexity of a raised vacuum chamber structure.
3Illumination intensity
If color filters are used to achieve full-color display, then color purity is improved, but use of energy deteriorates due to power consumption
Solution Approach 1:
The patent extracts and eliminates the color filter component from the display structure by directly forming color-specific luminescent layers in the light-emitting layer. This removes the need for color filters that would otherwise absorb and waste light energy, thereby improving power consumption while maintaining color purity through direct luminescence from the EL elements.
4Productivity
If multiple light-emitting layers are deposited linearly for different colors, then productivity is improved, but color mixing occurs due to deposited material infiltration
Solution Approach 1:
The bank structure is formed in advance as a preliminary action to define the deposition regions for different colors. This pre-formed structure guides the linear deposition of luminescent materials, ensuring that each color is deposited only in its designated region and preventing infiltration and color mixing, while maintaining high deposition efficiency.
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 solution enables higher resolution displays with reduced color mixing and lower power consumption by using a layered structure that inhibits energy transfer between light-emitting layers, eliminating the need for color filters and optical interference effects, thus improving color purity and light distribution properties.
Implementation Method 1
The EL element emits light by using the release of light during the deactivation of excitons that are generated by injecting electrons and holes into the light-emitting layer and causing recombination
Implementation Method 2
a separation layer that inhibits Förster-type energy transfer is layered between the third light-emitting layer and the light-emitting layer, of the first light-emitting layer and the second light-emitting layer, that is located closer to the third light-emitting layer
Data Source
AI summary
A blue fluorescent light-emitting layer is provided in common for first and second subpixels, a green fluorescent light-emitting layer is provided in common for second and third subpixels, and a red light-emitting layer is provided in common for the second and fourth subpixels. In the second subpixel, an opposing surface distance is less than or equal to a Förster radius, and at least of the blue fluorescent light-emitting layer and the green fluorescent light-emitting layer are layered with the red light-emitting layer with a separation layer interposed therebetween.