Patterned Optical Film for OLED Color Conversion Efficiency
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Solution Overview
Problem
Organic light emitting diode (OLED) displays with blue light emitting sources and green and red color conversion materials face efficiency losses due to absorption of unconverted blue light, and the inclusion of light scattering particles disrupts polarization, leading to increased ambient reflection.
Innovation Solution
A patterned optical film is placed between the circular polarizer and the light conversion layer, which is substantially transmissive to blue light in blue pixels and reflective to blue light in green and red pixels, recycling unconverted blue light and improving color conversion efficiency without sacrificing low ambient reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light scattering particles are included to recycle unconverted blue light, then color conversion efficiency is improved, but polarization is disrupted leading to increased ambient reflection
Solution Approach 1:
The optical film is divided into multiple thin layers (at least 10 layers) with alternating high refractive index and low refractive index materials. This segmentation creates a multilayer interference structure that selectively reflects blue light while maintaining polarization, resolving the contradiction between efficiency improvement and polarization disruption.
Solution Approach 2:
The patent changes the optical parameters by using alternating layers with different refractive indices (high refractive index material and low refractive index material) and controlling layer thicknesses (each layer less than 500 nm thick). This parameter optimization enables selective wavelength reflection while preserving polarization state, avoiding the ambient reflection increase caused by scattering particles.
2Object-affected harmful factors
If a multilayer optical film with at least 10 layers is used to maintain polarization and selectively reflect blue light, then ambient reflection is controlled, but device complexity increases
Solution Approach 1:
The patent uses thin film technology with each layer being less than 500 nm thick, making the multilayer structure compact and integrated. This thin-film approach achieves the desired optical functionality without adding significant device complexity, as the layers can be deposited directly onto existing display components.
Solution Approach 2:
The optical film employs composite material structure with alternating high refractive index and low refractive index materials. This composite approach achieves complex optical functionality (polarization maintenance and selective reflection) through material composition rather than mechanical complexity, simplifying the overall device architecture.
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 solution enhances blue to green and blue to red color conversion efficiency while maintaining low ambient reflection, addressing the efficiency losses and polarization disruption issues in existing OLED displays.
Implementation Method 1
A multilayer continuous optical film is provided. The multilayer continuous optical film includes a plurality of layers numbering at least 10 in total where each layer has an average thickness less than about 500 nm
Implementation Method 2
each region of the optical film that is disposed between a blue light emitting source and the corresponding green or red light emitting pixel transmits at least 70% of the incident light for each of the green and red peak wavelengths, and reflects at least 50% of the incident light having the blue peak wavelength
Data Source
AI summary
A display includes a pixelated emission surface including a plurality of blue, green and red light emitting pixels having emission peaks at respective blue, green and red peak wavelengths. The display includes a plurality of blue light emitting sources aligned to the plurality of blue, green and red light emitting pixels in a one-to-one correspondence. An optical film is disposed between the emission surface and the plurality of blue light emitting sources. Each region of the optical film that is disposed between a blue light emitting source and the corresponding blue light emitting pixel transmits at least 70% of substantially normally incident light having the blue peak wavelength. Each region of the optical film that is disposed between a blue light emitting source and the corresponding green or red light emitting pixel reflects at least 50% of substantially normally incident light having the blue peak wavelength.