Common Green Light-Emitting Layer for OLED Displays
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Solution Overview
Problem
Current display apparatus technologies face challenges in achieving high resolution, low power consumption, and cost-effectiveness due to issues with color mixing, energy loss, and complex manufacturing processes, particularly in self-luminous organic electroluminescence (EL) displays using the white color filter technique and separate-patterning methods.
Innovation Solution
A display apparatus with a layered structure comprising a common green light-emitting layer and separate blue and red light-emitting layers, where the green light-emitting layer is formed across all subpixels and the blue and red layers are patterned individually, with a separation layer between the green and blue layers to prevent energy transfer, eliminating the need for color filters and allowing for independent luminescent color emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the white color filter technique is used to form full-color organic EL display, then the luminescent color efficiency is improved, but the device complexity and manufacturing difficulty increase due to requiring multiple light-emitting layers and color filters for each subpixel
Solution Approach 1:
The patent merges the green light-emitting layer into a common layer shared by all subpixels (R, G, B subpixels), eliminating the need for separate green light-emitting layers in each subpixel. This combining approach maintains the luminescent color efficiency of the white color filter technique while significantly reducing the overall device complexity and number of manufacturing steps.
Solution Approach 2:
The green light-emitting layer serves multiple functions: it provides green emission for G subpixels and contributes to yellow emission for R subpixels (when combined with the red light-emitting layer), while also serving as an energy transfer source for the blue light-emitting layer in B subpixels. This multi-functionality reduces the total number of light-emitting layers required.
2Manufacturing precision
If separate-patterning vapor deposition is performed for individual colors, then the manufacturing precision is improved, but the productivity decreases due to requiring multiple vapor deposition masks and sequential processing steps
Solution Approach 1:
The patent combines the deposition of green and blue light-emitting layers into a single vapor deposition step using a shared mask pattern, eliminating the need for separate deposition steps for these layers. This merging of steps maintains the patterning precision required for individual subpixels while significantly improving manufacturing productivity by reducing the total number of deposition cycles.
Solution Approach 2:
The patent performs preliminary patterning of the light-emitting layer openings in the bank structure before vapor deposition, allowing the subsequent deposition step to simply fill the pre-defined patterns. This preliminary action enables high manufacturing precision without requiring complex mask patterns during deposition, thereby improving overall productivity.
3Manufacturing precision
If color filters are used in each subpixel to achieve full-color display, then the luminescent color accuracy is improved, but the energy loss increases due to absorption and filtering of light
Solution Approach 1:
The patent extracts and eliminates the color filter components from the display structure by using self-emissive organic EL light-emitting layers that directly generate red, green, and blue light. This extraction removes the energy-lossy filtering step while maintaining color accuracy through the inherent emission characteristics of the organic luminescent materials.
Solution Approach 2:
The patent converts the potential harm of energy loss through color filtering into a benefit by using the natural photoluminescence emission of organic compounds. The organic EL layers emit light at specific wavelengths corresponding to their energy levels, providing accurate colors without the need for energy-absorbing color filters. The energy that would have been lost in filtering is now directly utilized for light emission.
4Adaptability or versatility
If multiple light-emitting layers are formed in each subpixel to achieve white light emission, then the luminescent color versatility is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the green light-emitting layer into a common layer that serves all subpixel types, and combines the deposition of green and blue layers in a single vapor deposition step. This merging maintains the color versatility needed for full-color display while dramatically simplifying the manufacturing process and reducing costs by eliminating redundant layers and steps.
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
This configuration enhances luminescent color efficiency, reduces power consumption, and simplifies manufacturing by preventing color mixing and shifting, enabling higher resolution and lower production costs.
Implementation Method 1
a first light-emitting layer containing a first fluorescent luminescent material, a second light-emitting layer containing a second fluorescent luminescent material
Implementation Method 2
a third light-emitting layer containing a third fluorescent luminescent material or a phosphorescent luminescent material
Implementation Method 3
A distance between the first light-emitting layer and the second light-emitting layer in the first subpixel is greater than a Förster radius
Data Source
AI summary
Provided is a display apparatus where: a green light-emitting layer is common to a first subpixel, a second subpixel, and a third subpixel; a blue light-emitting layer is formed solely in the first subpixel; the red light-emitting layer is formed solely in the third subpixel; and in the first subpixel a separation layer is formed between the blue light-emitting layer and the green light-emitting layer.