Color-Change Material Layer for OLED Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OLED devices suffer from inefficiencies in light extraction due to internal reflection, with up to 80% of generated photons being trapped, and color-change material systems face challenges in converting higher-frequency light to lower frequencies effectively, leading to reduced display performance and sharpness.
Innovation Solution
A color-change material layer comprising a material that converts light of a second frequency range to a first frequency range, intermixed with a transparent material of refractive index at least 1.6, which is substantially non-scattering to the first frequency range, improving light output and sharpness by redirecting less than 25% of incident light without conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If color-change materials are used to convert high-frequency light to lower frequencies, then the desired color light is produced, but much of the high-frequency light does not interact with the color-change materials and is not converted
Solution Approach 1:
A transparent material with refractive index of at least 1.6 is introduced as an intermediary between the high-frequency light source and the color-change material. This intermediary material enhances the interaction between light and color-change material through refractive index matching, increasing the probability that high-frequency photons will be absorbed and converted to the desired lower frequencies.
Solution Approach 2:
The refractive index parameter of the transparent material is specifically optimized to be at least 1.6 to maximize light-matter interaction. By controlling this optical parameter, the system achieves improved conversion efficiency without requiring changes to the color-change material composition or structure.
2Object-affected harmful factors
If color-change materials are combined with color filters, then ambient light absorption and contrast are improved, but device efficiency decreases due to light absorption by filters
Solution Approach 1:
The patent extracts and separates the functions of ambient light rejection and color conversion. Color filters are removed from the optical path, and their ambient light rejection function is replaced by positioning color-change materials directly over the light-emitting elements, allowing each pixel to inherently reject non-emitted wavelengths while maintaining high efficiency.
Solution Approach 2:
Each light-emitting element serves its own color conversion needs through the integrated color-change material layer. The system becomes self-sufficient, with each pixel converting its emitted high-frequency light to the desired color without requiring external color filters, thereby eliminating the 2/3 light loss associated with traditional filter-based approaches.
3Loss of energy
If scattering layers are used to improve light extraction, then trapped light is redirected, but image sharpness and pixel definition are reduced
Solution Approach 1:
The color-change material layer is applied locally and directly over each light-emitting element rather than using a general scattering layer across the entire display. This localized approach ensures that light conversion occurs only at the intended pixel locations, maintaining sharp pixel definition while still improving light extraction through the refractive index-matched transparent material.
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
Enhances light extraction efficiency and sharpness by effectively converting trapped light into usable light output, improving the overall performance of OLED devices by reducing light loss and maintaining image clarity.
Implementation Method 1
The color-change materials absorb the high-frequency light and re-emit light at lower frequencies
Implementation Method 2
color-change materials convert light, for example blue light, of the common light-emitter into different colored light of the desired frequencies
Implementation Method 3
a transparent material having a refractive index of at least 1.6 intermixed with the color-change material
Data Source
AI summary
A color-change material layer comprising: a color-change material that converts light of a second frequency range higher than a first frequency range to light of the first frequency range; and a transparent material having a refractive index of at least 1.6 intermixed with the color-change material, wherein the layer is substantially non-scattering to light of the first frequency range.