OLED Packaging Film Refractive Index Gradient for Light Extraction
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Solution Overview
Problem
The out-coupling efficiency of OLED devices is low due to the waveguide effect in the thin film packaging structure, which consumes light and reduces the emission efficiency.
Innovation Solution
A light-emitting device with a thin film packaging structure featuring a target packaging film layer having a first packaging portion and a second packaging portion, where the refractive index of the first portion is less than the second portion, allowing light to be refracted and emitted from the device, thereby preventing waveguide effects and improving emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional thin film packaging structure is used, then the device structure is simple and easy to manufacture, but the out-coupling efficiency is low due to waveguide effect
Solution Approach 1:
The packaging structure is divided into regions with different refractive indices: a first region with refractive index n1 and a second region with refractive index n2, where n1 < n2. This local differentiation of optical properties enables light refraction to escape the waveguide effect while maintaining overall structural simplicity and manufacturability.
Solution Approach 2:
The patent changes the refractive index parameter across different regions of the packaging structure. By creating regions with different refractive indices (n1 and n2), the optical path of light is modified, enabling light to refract out of the waveguide mode and improve out-coupling efficiency without complicating the manufacturing process.
2Loss of energy
If the refractive index of the packaging structure is increased, then light refraction is enhanced and out-coupling efficiency improves, but the waveguide effect is strengthened and light loss increases
Solution Approach 1:
Instead of uniformly increasing the refractive index, the patent applies local quality differentiation by creating regions with different refractive indices. The first region (n1) and second region (n2) with n1 < n2 work together to refract light outward while avoiding the creation of a strong uniform waveguide effect that would trap light.
Solution Approach 2:
The packaging structure is segmented into multiple regions with different optical properties. This segmentation allows the structure to perform multiple functions: the first region provides a transition zone for light refraction while the second region enhances out-coupling, collectively reducing the harmful waveguide effect.
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 the out-coupling efficiency of the light-emitting device by refracting light to the side, preventing waveguide effects and increasing the amount of light emitted from the device.
Implementation Method 1
a refractive index of the first packaging portion is less than a refractive index of the second packaging portion, and the target packaging film layer is configured to enable light emitted by the light-emitting unit to leave from a light emitting surface of the light-emitting device by refraction
Data Source
AI summary
The light-emitting device includes: a base substrate; a light-emitting unit, disposed on the base substrate; and a thin film packaging structure disposed on a side, distal from the base substrate, of the light-emitting unit, wherein the thin film packaging structure includes a target packaging film layer of at least one packaging film layer is provided with a first packaging portion and a second packaging portion which are arranged in the same layer and are in contact with each other, an orthographic projection of the first packaging portion on the base substrate at least partially overlaps an orthographic projection of the light-emitting unit on the base substrate, an orthographic projection of the second packaging portion on the base substrate at least partially overlaps the orthographic projection of the light-emitting unit, and a refractive index of the first packaging portion is less than a refractive index of the second packaging portion.