Radiation-Emitting Semiconductor Component with Functional Layer
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Solution Overview
Problem
LEDs based on luminescence conversion exhibit undesired angular dependency of color locus and an unwanted yellow color impression when switched off due to inefficiencies in radiation decoupling and color mixing.
Innovation Solution
A radiation-emitting semiconductor component with a luminescence conversion layer and a functional layer, where the functional layer, made of materials like glass, ceramic, or sapphire, follows the luminescence conversion layer to improve radiation coupling and color mixing, featuring a refractive index matching or lower than the luminescence conversion layer, and a surface structure to reduce reflection losses and enhance directional radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a luminescence conversion layer is applied to convert ultraviolet or blue light into yellow light, then white mixed light is produced, but an undesired angular dependency of the color locus occurs
Solution Approach 1:
A functional layer with refractive index n2 ≤ n1 is introduced between the luminescence conversion layer and the exit surface. This intermediary layer reduces reflection losses at the exit surface and improves radiation decoupling, thereby reducing the angular dependency of the color locus while maintaining the white light quality.
Solution Approach 2:
The refractive index parameter of the functional layer is specifically selected to be less than or equal to the refractive index of the luminescence conversion layer. This parameter change optimizes the optical coupling and radiation decoupling, reducing angular dependency of the emitted white light.
2Use of energy by moving object
If radiation is emitted at large angles of reflection, then more ultraviolet or blue radiation is converted into yellow light, but the color mixing becomes uncontrolled
Solution Approach 1:
The functional layer acts as an intermediary that controls the path of radiation exiting the luminescence conversion layer. By reducing reflection losses at the exit surface, it ensures more consistent conversion efficiency across different angles while maintaining controlled color mixing.
3Ease of manufacture
If the luminescence conversion layer gives a yellow color impression when the LED is switched off, then the layer is visible, but this creates an undesired aesthetic effect
Solution Approach 1:
The functional layer with refractive index n2 ≤ n1 serves as an optical intermediary that reduces reflection losses at the exit surface. This improvement in radiation decoupling reduces the visible yellow color impression of the luminescence conversion layer when the LED is switched off, while the layer remains manufacturable.
4Loss of energy
If reflection losses at the exit surface are high, then radiation decoupling is inefficient, but energy is lost
Solution Approach 1:
The functional layer with refractive index n2 ≤ n1 is introduced as an intermediary between the luminescence conversion layer and the exit surface. This intermediary reduces reflection losses by optimizing the refractive index transition, thereby improving radiation decoupling efficiency and reducing energy loss.
Solution Approach 2:
The refractive index parameter of the functional layer is optimized to be less than or equal to that of the luminescence conversion layer. This parameter change minimizes reflection losses at the exit surface, improving both energy efficiency and radiation decoupling productivity.
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 radiation decoupling and color mixing, reducing angular dependency and the yellow color impression, resulting in improved efficiency and directional emission of white light.
Implementation Method 1
a luminescence conversion layer (5), which converts at least part of the emitted radiation into radiation with an intensity maximum at a second wavelength λ2, which is greater than the first wavelength λ1
Implementation Method 2
The functional layer has a surface structure to reduce reflection losses and enhance directional radiation
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a radiation-emitting semiconductor component having a semiconductor body (1), which comprises an active layer (3) that emits electromagnetic radiation of a first wave length Lambda1 in a main radiation direction (13) during operation, and having a luminescence conversion layer (5) that converts at least a part of the emitted radiation into radiation of a second wave length Lambda2, which is greater than the first wave length Lambda1. A functional layer (6) for improving radiation uncoupling, color mixing and/or angular dependence of the emitted radiation follows the active layer (3) in the main radiation direction (13), wherein the functional layer (6) contains glass, ceramics, glass ceramics or sapphire.