Reflective Light Conversion Films for LED Uniformity
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Solution Overview
Problem
Conventional quantum dot (QD)-LEDs suffer from unideal illumination uniformity and high color temperature due to excessive blue light emission, with most short-wavelength light passing through the light conversion layer without being converted to red or green light.
Innovation Solution
A light conversion material with a light reflective structure, comprising a transparent substrate and alternating first and second light conversion films, where the second films have a higher refractive index than the first, reflecting unconverted short-wavelength light back into the films to enhance conversion to red and green light, thereby preventing direct passage and improving illumination uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If quantum dots are used as light conversion material to convert short-wavelength light to red and green light, then the LED can emit white light, but most short-wavelength light passes through without conversion causing unideal illumination uniformity and high color temperature
Solution Approach 1:
The patent converts the harmful unconverted short-wavelength blue light into a beneficial resource by using a reflective structure with higher refractive index to bounce the blue light back into the light conversion layer, where it can be converted to red and green light by quantum dots, thus transforming the harmful excessive blue light emission into useful red and green light components
Solution Approach 2:
The patent introduces a new dimensional approach by adding a reflective structure with higher refractive index above the light conversion layer, creating an optical cavity effect that traps and recycles unconverted short-wavelength light within the light conversion layer, thereby improving illumination uniformity and reducing color temperature
2Temperature
If a light conversion layer with quantum dots is used, then red and green light can be generated, but the color temperature exceeds 10,000K due to dominant blue light
Solution Approach 1:
The patent converts the harmful excessive blue light into useful red and green light by using the reflective structure to trap and recycle unconverted short-wavelength light within the quantum dot layer, where it undergoes additional conversion to red and green wavelengths, thereby reducing color temperature from over 10,000K to a more comfortable range
3Productivity
If the light conversion layer is designed with single layer structure, then the device complexity is low, but the light conversion efficiency is insufficient
Solution Approach 1:
The patent enhances light conversion efficiency by adding a vertical dimension to the optical path through a reflective structure with higher refractive index positioned above the light conversion layer, creating a light-trapping cavity that increases the effective interaction length between blue light and quantum dots without significantly increasing horizontal device complexity
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 effectively recycles unconverted short-wavelength light, resulting in enhanced illumination uniformity and a lower color temperature, with the LED emitting a more balanced white light with increased intensity and improved color rendering.
Implementation Method 1
parts of the short-wavelength light not be converted to red light and/or green light have a reflected light forming at the junction between the first light conversion film and the second light conversion film
Implementation Method 2
the refractive index of the second light conversion film is greater than that of the first light conversion film
Implementation Method 3
when a short-wavelength light passes through the transparent substrate and is subsequently incident on the first light conversion films and the second light conversion films, parts of the short-wavelength light being converted to red light and/or green light
Data Source
AI summary
The present invention discloses a light conversion material with light reflective structure, comprises: a transparent substrate, a plurality of first light conversion films and second light conversion films. Particularly, the second light conversion film is disposed between two of the first light conversion films, and has a refractive index greater than that of the first light conversion film. By such design, when a short-wavelength light is incident on the first light conversion films and the second light conversion films, parts of the short-wavelength light have a reflected light forming at the junction between the two light conversion films, and the reflected light would bounce back to the first light conversion film and/or the second light conversion film, thereby those unconverted short-wavelength light being prevented from directly passing the light conversion material. Briefly speaking, this light conversion material exhibits an outstanding performance on short-wavelength light recycling.