Stacked Light-Emitting Element Optimizing Power Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing white light-emitting elements prioritize white light emission, resulting in limitations to power efficiency due to the use of low luminosity wavelength ranges, and struggle to achieve natural color lighting like light bulb or warm white colors.
Innovation Solution
A light-emitting element with at least three stacked units, each with a light-emitting layer emitting one color, featuring a peak in the yellow to orange wavelength range and a peak in the blue wavelength range, utilizing phosphorescent compounds for high luminosity and fluorescent compounds for long lifetime, respectively, to improve power efficiency and achieve natural color emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If white light emission is prioritized using multiple light-emitting units with emission peaks in red, green, and blue wavelength ranges, then white light can be emitted, but power efficiency is limited due to use of low luminosity wavelength ranges
Solution Approach 1:
The light-emitting element is divided into three distinct light-emitting units, each responsible for a specific color range (red, green, blue). This segmentation allows optimization of each unit's emission characteristics while collectively achieving white light, resolving the contradiction by enabling selective enhancement of luminosity in key wavelength ranges without compromising overall white light emission.
Solution Approach 2:
The emission spectra of the light-emitting units are carefully adjusted with specific peak wavelengths (red: 610-680nm, green: 500-560nm, blue: 440-480nm) and controlled full width at half maximum values (40-80nm). This parameter optimization ensures that each unit emits in high luminosity ranges while maintaining the ability to combine into white light, thereby improving power efficiency without sacrificing illumination quality.
2Illumination intensity
If light-emitting units with emission peaks in complementary colors (blue and yellow) are stacked to emit white light, then white light emission is achieved, but the amount of light in low luminosity color ranges is increased, limiting power efficiency improvement
Solution Approach 1:
Instead of using broad-spectrum yellow emission, the invention assigns specific local quality characteristics to each light-emitting unit: red unit (610-680nm), green unit (500-560nm), and blue unit (440-480nm). This local optimization ensures that each unit operates in high luminosity wavelength ranges, improving overall power efficiency while maintaining white light emission capability through spectral combination.
3Use of energy by moving object
If phosphorescent compounds are used for high luminosity, then power efficiency is improved, but lifetime is reduced compared to fluorescent compounds
Solution Approach 1:
The light-emitting units are segmented by emission color, with blue and green units using fluorescent compounds for extended lifetime, and red units using phosphorescent compounds for high luminosity. This segmentation allows each unit to use the most appropriate material type for its specific wavelength range, balancing overall power efficiency and lifetime without requiring compromise across all units.
Solution Approach 2:
The light-emitting element employs a composite structure combining different types of light-emitting compounds (fluorescent and phosphorescent) in different units. This composite approach leverages the advantages of each material type: fluorescent compounds provide long lifetime in blue/green ranges where stability is critical, while phosphorescent compounds provide high luminosity in red ranges, achieving both high power efficiency and extended overall device lifetime.
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 maximally improves power efficiency and extends the lifetime of the light-emitting element, enabling the production of light with a color temperature within the range of light bulb or warm white, closely aligning with the blackbody locus in the chromaticity diagram, thus providing high power efficiency and natural color lighting.
Implementation Method 1
a light-emitting element utilizing electroluminescence... By applying voltage between the pair of electrodes of the light-emitting element, light can be emitted from the light-emitting substance
Implementation Method 2
utilizing phosphorescent compounds for high luminosity... at least three light-emitting units are stacked. The light-emitting units each include a light-emitting layer which emits light of one color
Implementation Method 3
fluorescent compounds for long lifetime... The other peak is located in the blue wavelength range (i.e., the wavelength greater than or equal to 400 nm and less than 480 nm)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To provide a light-emitting element whose power efficiency is improved and which emits light of natural color like light bulb color. In the light-emitting element, at least three light-emitting units are stacked. The emission spectrum of the light-emitting element has two peaks. One of the two peaks is obtained by combining spectra of light emitted from two light-emitting units. The peak is in the yellow to orange wavelength range and has a wavelength greater than or equal to 560 nm and less than 580 nm. Thus, a wavelength range of high luminosity can be used and the power efficiency can be improved. The color of light emitted from the light-emitting element is close to a blackbody locus in a chromaticity diagram, and light of natural color like light bulb color can be achieved.