Transflective Layer Diffusive Structure for OLED Brightness
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Solution Overview
Problem
Organic light emitting diode (OLED) display devices face reduced brightness due to total reflection of light at the interfacial surfaces, limiting their viewing angle and color reproducibility.
Innovation Solution
A display device with a transflective layer comprising alternately arranged diffusive layers of different refractive indices and via holes filled with a third diffusive material, which enhances light emission by diffusing and refracting light to increase brightness and color reproducibility across a wider viewing angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity is formed to improve brightness using interference of light reflected from electrode, then light intensity at specific wavelength in front direction is increased, but light intensity in other wavelengths is decreased and color reproducibility is degraded
Solution Approach 1:
The transflective layer is segmented into multiple diffusive layers with different refractive indices (first diffusive layers with first refractive index, second diffusive layers with second refractive index) arranged alternately. This segmentation allows each layer to contribute differently to light diffusion, achieving both brightness enhancement and color reproducibility without the wavelength-selective interference effects of microcavities.
Solution Approach 2:
Different regions of the transflective layer have different optical properties through the alternating diffusive layers with different refractive indices. This local variation in optical quality enables selective diffusion of light at different locations and angles, improving overall brightness while maintaining color accuracy across the viewing angle.
2Illumination intensity
If light is emitted perpendicular to the surface, then brightness at normal viewing angle is maximized, but viewing angle and light emission in other directions is limited
Solution Approach 1:
The alternating diffusive layers with different refractive indices create multi-dimensional light diffusion pathways. Light is scattered not only in the vertical direction but also in horizontal directions, enabling light emission across a wide viewing angle spectrum rather than being confined to the normal viewing direction.
Solution Approach 2:
By changing the refractive index parameter across different layers (first refractive index for first diffusive layers, second refractive index for second diffusive layers), the patent controls light diffusion characteristics to achieve wide-angle emission while maintaining brightness. The via holes filled with third diffusive material further modify the refractive index distribution to enhance viewing angle.
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 significantly improves brightness efficiency and color reproducibility by allowing light to be emitted in directions other than perpendicular to the surface, resulting in enhanced viewing angle performance compared to traditional OLED display devices.
Implementation Method 1
a transflective layer including first diffusive layers 210, 230, and 250 having a first refractive index, and second diffusive layers 220 and 240 having a second refractive index different from the first refractive index, alternately arranged on the substrate
Implementation Method 2
first diffusive layers 210, 230, and 250 having a first refractive index, and second diffusive layers 220 and 240 having a second refractive index different from the first refractive index, alternately arranged on the substrate
Data Source
AI summary
The present invention provides a display device and a method of fabricating the same. The display device includes a substrate, a transflective layer including first diffusive layers and second diffusive layers alternately arranged on the substrate, the first diffusive layers including a first diffusive material having a first refractive index, and the second diffusive layers including a second diffusive material having a second refractive index different from the first refractive index, a plurality of via holes formed in the transflective layer, and a light-emitting layer disposed on the substrate.