Bragg Reflection Unit for Display Substrate Light Extraction
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Solution Overview
Problem
Display substrates, particularly those using OLEDs, suffer from low light-emitting efficiency due to absorption, loss, and interface scattering, limiting their effectiveness in achieving full-color displays.
Innovation Solution
A display substrate with Bragg reflection units composed of alternately stacked layers with different refractive indices, where the thickness of each layer is optimized to ¼ of the wavelength of incident light, enhancing light-emitting efficiency and enabling full-color displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If normal LED or OLED backlight is used in display, then the display can be implemented, but the light-emitting efficiency is low due to absorption, loss, interface scattering and reflection
Solution Approach 1:
The backlight module is segmented into multiple functional layers including a Bragg reflection structure with alternating high and low refractive index layers. This segmentation allows specific control of light propagation in different layers, reducing unnecessary light absorption and improving overall light-emitting efficiency while maintaining manufacturability through standardized layer deposition processes
Solution Approach 2:
The invention converts the harmful effect of light reflection and scattering at interfaces into a beneficial effect by using the Bragg reflection structure. The alternating refractive index layers are designed to reflect specific wavelengths constructively, turning interface reflections that cause loss into a mechanism that enhances light extraction efficiency and improves overall luminance
2Illumination intensity
If OLED is used for display, then uniform luminance and flicker-free display are achieved, but light-emitting efficiency is only about 20% due to absorption and loss
Solution Approach 1:
The Bragg reflection structure is designed with locally optimized refractive index profiles in different layers to match the specific optical characteristics of OLED emission. The alternating high and low refractive index layers are configured with specific thicknesses and materials to maximize light extraction at the OLED interface while maintaining uniform luminance across the display area
Solution Approach 2:
The invention uses composite material structures with alternating high refractive index materials (such as TiO2 or SiO2) and low refractive index materials in the Bragg reflection layers. This composite structure creates optimal optical impedance matching between the OLED and the display medium, significantly improving light-emitting efficiency while preserving the uniform luminance characteristics of OLED
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 optimized Bragg reflection structure significantly improves light-emitting efficiency and luminance, allowing for effective full-color displays by concentrating and enhancing light emission while reducing loss.
Implementation Method 1
Bragg reflection structure (i.e. Distributed Bragg Reflector, DBR) is formed generally by alternately stacking high-refractive index material layers and low-refractive index material layers
Implementation Method 2
each bragg reflection unit comprises a first structural layer and a second structural layer which are alternately stacked with each other and have different refractive indexes; thickness of the first structural layer is 1⁄4n1 of wavelength of incident light
Data Source
AI summary
The present invention relates to the technical field of display, and provides a display substrate and a preparing method thereof which can solve the problem of lower light-emitting efficiency of the display substrate in the prior art. The display substrate of the present invention comprises a plurality of display units of at least two different colors. The display substrate further comprises a plurality of bragg reflection units in different regions corresponding to respective display units, each bragg reflection unit comprises first structural layer and second structural layer which are alternately stacked with each other and have different refractive indexes; thickness of each of the first and second structural layers is ¼n wavelength of incident light from corresponding display unit, wherein n is refractive index of the first or the second structural layer. The display substrate of the present invention has higher light-emitting efficiency and is applicable to full-color display.