Buffer Layer Refractive Index Gradient for Light Emitting Devices
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Solution Overview
Problem
Conventional light emitting devices have limited orientation angles, leading to non-uniform brightness distribution in display applications, as the light is concentrated around the normal line, resulting in irregular image quality due to narrow output angles.
Innovation Solution
A light emitting device with a substrate and a buffer layer having a decreasing refractive index from the light-emitting structure towards the substrate, expanding the orientation angle by spreading the light more widely through the use of multiple sub-layers with varying refractive indices and thicknesses, allowing for increased optical power and uniform brightness across a display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional buffer layer with uniform refractive index is used, then the device structure is simple, but the orientation angle is limited and brightness distribution is non-uniform
Solution Approach 1:
The buffer layer is divided into multiple sub-layers (first buffer layer, second buffer layer, third buffer layer) with different refractive indices. Each sub-layer has a specific refractive index range, creating a gradient structure that progressively transforms the light from the high-refractive-index light-emitting structure to the lower-refractive-index substrate, thereby expanding the orientation angle and achieving uniform brightness distribution.
Solution Approach 2:
Different regions of the buffer layer are assigned different refractive indices to optimize light extraction at various angles. The first buffer layer adjacent to the light-emitting structure has a refractive index of 1.8-2.2, the second buffer layer has 1.6-1.9, and the third buffer layer has 1.4-1.7, creating localized optical properties that collectively expand the orientation angle and improve brightness uniformity.
2Illumination intensity
If the refractive index is decreased toward the substrate, then the orientation angle is expanded, but the manufacturing precision requirement increases
Solution Approach 1:
The continuous refractive index gradient is segmented into discrete steps with three buffer layers, each having a specific refractive index range. This segmentation makes the manufacturing process more controllable while still achieving the desired light spreading effect, as each layer can be independently optimized within its specified refractive index range.
Solution Approach 2:
The refractive index parameter is systematically changed across the buffer layer structure, decreasing from 1.8-2.2 in the first buffer layer to 1.6-1.9 in the second buffer layer, and finally to 1.4-1.7 in the third buffer layer. This parameter progression achieves orientation angle expansion while maintaining manufacturability through defined parameter ranges.
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 expanded orientation angle enhances the optical power and achieves uniform brightness across the display panel, improving image quality by ensuring consistent light distribution.
Implementation Method 1
the refractive index of the buffer layer being decreased toward the substrate from the light-emitting structure
Data Source
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AI summary
Disclosed is a light emitting device including a substrate, a buffer layer on the substrate, and a light-emitting structure on the buffer layer. The buffer layer has a refractive index decreased toward the substrate from the light-emitting structure.