Luminescence Conversion Layer Composite with Scattering Film
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Solution Overview
Problem
Existing radiation-emitting optoelectronic components with luminescence conversion layers for producing white light have unsatisfactory visual impressions in the switched-off state due to unwanted yellow light emission, and the color impression is sensitive to deviations in layer thicknesses of luminescence and scattering layers.
Innovation Solution
A process for producing a layer composite using a molding press with precise control over layer thicknesses, involving a luminescence conversion layer and a scattering layer, where a first polymer with a luminescence conversion substance is hardened, followed by a second polymer with scattering particles, both on a support film, allowing for high precision and adherence between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a luminescence conversion layer is used to produce white light, then white light generation is achieved, but the visual impression in the switched-off state becomes unsatisfactory due to yellow color emission
Solution Approach 1:
A scattering layer is introduced as an intermediary between the luminescence conversion layer and the observer. This scattering layer diffuses the yellow light emitted by the luminescence conversion layer in the switched-off state, making the yellow color imperceptible to observers while preserving the white light generation function when activated.
2Ease of manufacture
If the thicknesses of luminescence conversion layer and scattering layer are not precisely controlled, then production is simpler, but the color impression deviates from desired reference values
Solution Approach 1:
The support film is prepared in advance with predetermined thickness and material properties before the luminescence conversion layer and scattering layer are applied. This preliminary preparation establishes a stable baseline that compensates for variations in subsequent layer thicknesses, ensuring consistent color impression without requiring extreme precision in each individual layer's thickness.
Solution Approach 2:
The patent utilizes the refractive index difference between the support film and the luminescence conversion layer/scattering layer as a controllable parameter. By selecting materials with specific refractive indices, the optical path and light scattering behavior are optimized to maintain desired color characteristics even when layer thicknesses vary within acceptable ranges.
3Ease of manufacture
If a scattering layer is added to reduce yellow color impression, then switched-off state appearance improves, but layer thickness precision becomes more critical
Solution Approach 1:
The support film provides locally optimized optical properties at the interface between the luminescence conversion layer and scattering layer. By tailoring the refractive index and thickness of the support film specifically at this critical interface, the system achieves robust yellow color suppression that is less sensitive to variations in the thickness of the overlying scattering layer.
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 process achieves high precision in layer thickness and homogeneity, reducing the yellow color impression in the switched-off state and ensuring consistent white light production, with improved chromaticity and brightness when applied to optoelectronic semiconductor chips.
Implementation Method 1
at least some of the radiation emitted by an active layer of the optoelectronic component is converted by a luminescence conversion layer to longer wavelengths
Implementation Method 2
a light-scattering layer, which contains, e.g., scattering particles, above the luminescence conversion layer
Data Source
AI summary
A process of producing a layer composite includes a luminescence conversion layer and a scattering layer, wherein a press having a first pressing tool with a cavity and a second pressing tool is used including introducing a first polymer including a luminescence conversion substance into the cavity, inserting a film between the first and second tools, closing the press and carrying out a first pressing, hardening the first polymer to form a luminescence conversion layer in the press, opening the press, wherein the luminescence conversion layer adhering to the film remains in the press, introducing a second polymer including scattering particles into the cavity, closing the press and carrying out a second pressing, hardening the second polymer to form a scattering layer disposed on the luminescence conversion layer, opening the press, and removing the support film with the layer composite including the luminescence conversion layer and the scattering layer.