Optical Film with Curved Grooves for OLED Color Shift Reduction
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Solution Overview
Problem
Organic light-emitting diodes (OLEDs) with microcavity structures experience color shift issues due to changes in the thickness of the organic deposition material layer, leading to variations in the wavelengths amplified, resulting in color shifts when viewed from different angles, such as a blue shift causing white to appear bluish at lateral sides.
Innovation Solution
An optical film with a high refractive index pattern layer and a low refractive index pattern layer, featuring grooves with curved surfaces and fillers, is applied to the OLEDs. The grooves are two-dimensionally arranged with varying distances in different directions, and the layers are designed to refract and emit light in various directions, mixing light beams and reducing color shift across different viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity structure with fixed thickness is used to amplify specific wavelengths, then luminance and color purity are improved, but color shift occurs when viewed from lateral angles due to effective thickness changes
Solution Approach 1:
The patent introduces an optical film with spatially varying refractive index distribution, where different regions have different refractive indices to compensate for the angle-dependent effective thickness changes in the microcavity structure. This local variation in optical properties maintains consistent color characteristics across different viewing angles while preserving the luminance enhancement from the microcavity structure.
Solution Approach 2:
The patent changes the refractive index parameter of the optical film to compensate for the effective thickness variation of the microcavity structure at different viewing angles. By adjusting the refractive index distribution, the optical path length is modified to maintain consistent resonant wavelengths across different observation angles, thereby eliminating color shift while preserving luminance.
2Manufacturing precision
If the organic deposition material layer thickness is optimized for front viewing, then color purity is improved, but color shift occurs at lateral viewing angles
Solution Approach 1:
The patent introduces an optical film as an intermediary element between the viewer and the microcavity structure. This optical film mediates the optical interaction by compensating for the angle-dependent effective thickness changes, allowing the microcavity structure to maintain its optimized thickness for front viewing while achieving viewing angle independence through the refractive index distribution in the optical film.
3Ease of manufacture
If a simple planar optical film is used, then manufacturing is simple, but it cannot compensate for color shift caused by lateral viewing angles
Solution Approach 1:
The patent employs a composite optical film structure with materials having different refractive indices arranged in a specific pattern. This composite structure enables the film to compensate for color shift at lateral viewing angles while maintaining compatibility with existing manufacturing processes, thus achieving both manufacturing simplicity and color shift compensation.
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 optical film effectively reduces color shift across the overall azimuth angle range, improving visual characteristics and maintaining color purity by uniformly combining light beams' optical characteristics, thereby minimizing the impact of viewing angle on color appearance.
Implementation Method 1
The grooves are two-dimensionally arranged with varying distances in different directions, and the layers are designed to refract and emit light in various directions, mixing light beams and reducing color shift across different viewing angles.
Data Source
AI summary
An optical film includes: a high refractive index pattern layer including a material having a refractive index greater than about 1, where a plurality of grooves, each having a curved groove surface and a depth greater than a width thereof, is defined on a first surface of the high refractive index pattern layer, the plurality of grooves defines a pattern, the plurality of grooves are two-dimensionally arranged in a first direction and a second direction, and a first distance between adjacent grooves in the first direction and a second distance between adjacent grooves in the second direction are different from each other; and a low refractive index pattern layer including a material having a refractive index less than the refractive index of the high refractive index pattern layer and further including a plurality of fillers which fills the plurality of grooves, respectively.