White-light LED with Common Unpatterned Layer for Angular Color Stability
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Solution Overview
Problem
Existing LED devices suffer from angular color dependence and inefficiencies due to trapped light and the use of patterned deposition technologies, which increase manufacturing costs and reduce light output.
Innovation Solution
A light-emitting diode device with a common unpatterned white-light-emitting layer and optically structured portions, where one portion is tuned to emit white light and the other to emit colored light, improving color stability by combining light from these portions to maintain a stable spectrum across angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If optical microcavity structures are used to improve color control, then color stability is improved, but angular color dependence worsens
Solution Approach 1:
The device is divided into multiple independently addressable subpixels (red, green, blue, white) within a single pixel unit. Each subpixel has its own optical microcavity structure tuned to specific wavelengths. By segmenting the pixel and independently controlling each subpixel's brightness, the invention achieves color stability while mitigating angular color dependence through computational color mixing.
Solution Approach 2:
The invention combines multiple light-emitting materials with different emission characteristics (red, green, blue phosphors/quantum dots, and white-light-emitting organic material) within a single pixel. This composite approach allows the system to maintain color stability across viewing angles by adjusting the relative intensities of each material's emission through independent subpixel control.
2Manufacturing precision
If patterned deposition technology is used to create optical microcavities, then color control is improved, but manufacturing complexity increases
Solution Approach 1:
The optical microcavity structures are segmented into discrete subpixel units (red, green, blue, white) that can be independently addressed. This segmentation allows for simplified manufacturing by enabling separate optimization of each subpixel's optical cavity while using the same base deposition process, reducing overall manufacturing complexity.
Solution Approach 2:
The same optical deposition process and microcavity structure design are used across all subpixel types (red, green, blue, white), making the manufacturing process universal. The multi-functionality is achieved by tuning the same basic structure to different wavelengths through parameter adjustment rather than requiring entirely different manufacturing processes for each color.
3Manufacturing precision
If color filters are used to achieve color emission, then color purity is improved, but light output efficiency decreases
Solution Approach 1:
The invention extracts and eliminates the need for color filters by using directly emitting phosphor and quantum dot materials that produce pure colors through photoluminescence. By taking out the color filter component entirely and replacing it with wavelength-selective light-emitting materials, the system achieves both color purity and high light output efficiency, as no light is absorbed and re-emitted through filtering.
Solution Approach 2:
The invention uses photoluminescent materials (phosphors and quantum dots) that convert pump light to specific colors through wavelength transformation rather than absorption and filtering. This color change mechanism occurs in the emitting materials themselves, eliminating the need for separate color filters and maintaining high light output efficiency while achieving pure color emission.
4Manufacturing precision
If multiple optical microcavity structures are implemented, then color control is improved, but device complexity increases
Solution Approach 1:
Multiple optical microcavity structures (red, green, blue, white) are merged into a single integrated pixel unit with a common substrate and electrode structure. The subpixels share common structural elements such as the substrate, transparent electrode, and encapsulation layers, reducing overall device complexity while maintaining precise color control through independent optimization of each subpixel's optical cavity.
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 enhances angular color performance and maintains color stability when viewed from various angles, reducing the change in color and improving light output efficiency by minimizing the use of color filters and patterned deposition processes.
Implementation Method 1
an optical cavity structure producing optical interference effects will be present
Implementation Method 2
a large fraction (e.g. greater than 50%) of the emitted light is trapped in the device due to total internal reflection
Data Source
AI summary
A light-emitting diode device, includes a substrate; and a light-emitting element having two or more commonly-controlled portions, the light-emitting element having two electrodes and a common unpatterned white-light-emitting layer formed between the two electrodes, at least one portion having an optical spacer, each portion having a different optical structure, the optical structure in one portion being tuned to emit substantially white light and that one portion having a transparent electrode, and the optical structure in a different portion being tuned to emit colored light.