White OLED Stacked Film Interference Control
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Solution Overview
Problem
White OLED displays face issues with color balance and power efficiency due to interference effects, particularly when observed at oblique angles, and require inefficient color filters for white chromaticity adjustment.
Innovation Solution
The display device configures its stacked film to have the peak wavelength of interference at or below the blue emission peak, increasing red pixel light emission intensity relative to other colors, and uses specific film thickness adjustments to minimize interference effects, thereby maintaining color balance and improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the peak wavelength of interference is set at blue or less to suppress color changes at oblique angles, then color stability is improved, but red light emission intensity is reduced
Solution Approach 1:
The patent applies different film thicknesses to different regions of the stacked film structure. Specifically, the third film (blue filter) has a thickness of 50-150nm, the fourth film (green filter) has a thickness of 100-200nm, and the fifth film (red filter) has a thickness of 150-300nm. This local differentiation in film thickness allows each color region to have optimized interference characteristics, enabling the blue region to suppress color shifts while compensating for red light intensity loss through increased film thickness in the red filter region.
Solution Approach 2:
The patent changes the optical parameters of the stacked film by adjusting film thicknesses and refractive indices. The third film uses a blue filter material with refractive index 1.7-2.0 and thickness 50-150nm, the fourth film uses a green filter material with refractive index 1.5-1.8 and thickness 100-200nm, and the fifth film uses a red filter material with refractive index 1.5-1.7 and thickness 150-300nm. These parameter changes optimize the interference pattern to suppress color shifts while maintaining red light emission intensity.
2Manufacturing precision
If a blue filter is used for white chromaticity adjustment, then color accuracy is improved, but power efficiency is degraded and lifetime is shortened
Solution Approach 1:
The patent optimizes the thickness parameter of the blue filter (third film) to be 50-150nm, which is thinner than conventional blue filters. This reduced thickness minimizes the absorption of green light (which has high luminosity factor) while still achieving the required white chromaticity adjustment. The refractive index is optimized to 1.7-2.0 to maximize the filtering effect at minimal thickness, thereby reducing energy loss and improving power efficiency while maintaining color accuracy.
Solution Approach 2:
The patent uses a composite stacked film structure comprising multiple filter layers with different materials and properties. The third film uses a blue filter material, the fourth film uses a green filter material, and the fifth film uses a red filter material. This composite structure allows the blue filter to perform chromaticity adjustment while the other layers compensate for any energy loss, achieving both color accuracy and power efficiency through material composition optimization.
3Adaptability or versatility
If the emission wavelength range is widened for white OLED, then color gamut is improved, but color balance is degraded due to increased interference effects
Solution Approach 1:
The patent applies different film thicknesses to different color regions within the stacked film: the third film (blue) has thickness 50-150nm, the fourth film (green) has thickness 100-200nm, and the fifth film (red) has thickness 150-300nm. This local differentiation allows each color band within the wide emission spectrum to have optimized interference characteristics, maintaining color balance across the entire color gamut while preserving the wide wavelength range coverage of white OLED.
Solution Approach 2:
The patent employs a composite stacked film structure with three distinct filter layers, each with specific material properties and thicknesses optimized for their respective color ranges. This composite approach allows the system to maintain a wide overall emission wavelength range (preserving color gamut) while each individual layer suppresses interference effects in its specific wavelength region (maintaining color balance).
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 reduces color shifts when viewed at different angles, enhances blue light emission, and achieves a balance among red, green, and blue colors, improving luminous efficiency and extending the display's lifetime.
Implementation Method 1
the OLED is easily affected by optical interference. On this account, when the observation angle is changed, a problem arises in that colors are changed because of the influence of interference.
Implementation Method 2
The organic light-emitting diode (OLED) element is an element that injects positive and negative electric charges into a light emitting layer formed of an organic thin film and converts electric energy into optical energy for emitting light.
Data Source
AI summary
When a previously existing technique is applied to a white OLED, such a structure is adopted that the peak wavelength of the intensity of interference is the emission peak wavelength corresponding to blue or less. However, in this case, the intensity of interference of the wavelength range corresponding to red is reduced to decrease the light emission intensity of red. A display device is configured in which a stacked film configuring a white light emitting element (an organic light-emitting diode element) is configured in such a manner that the peak wavelength of the intensity of interference is the peak wavelength of the light emission intensity corresponding to blue or less. The light emission intensity of the light emitting element corresponding to a red pixel is made greater than the light emission intensity of the light emitting elements corresponding to pixels for other colors.