Wavelength-Conversion Display Stack With Reflective Optical Layer
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Solution Overview
Problem
Display devices using quantum dots for light conversion suffer from low directivity, leading to inefficient light extraction and power consumption, as a significant amount of converted light is emitted back to the light-emitting element rather than contributing to the display, limiting the power efficiency and light-extraction efficiency of these devices.
Innovation Solution
A display device structure incorporating a first and second light-emitting element, a wavelength-conversion layer, and an optically functional layer, where the optically functional layer transmits the first light and reflects the second light, enhancing light-extraction efficiency by optimizing the reflectance and transmittance properties to improve power efficiency and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quantum dots are used for wavelength conversion, then color conversion efficiency is improved, but light-extraction efficiency deteriorates due to low directivity causing light to be emitted back to the light-emitting element
Solution Approach 1:
The patent applies the inversion principle by placing a reflective layer between the light-emitting element and the wavelength conversion layer. This reflective layer inverts the normal optical path by reflecting light that would otherwise be absorbed back toward the wavelength conversion layer, thereby converting wasted light into useful converted light and resolving the light-extraction efficiency problem while maintaining color conversion efficiency.
Solution Approach 2:
The patent uses a reflective layer as an intermediary component between the light-emitting element and the wavelength conversion layer. This intermediary layer mediates the optical interaction by reflecting unconverted light back through the wavelength conversion layer, enabling secondary wavelength conversion and improving overall light-extraction efficiency without compromising the primary color conversion function.
2Adaptability or versatility
If quantum dots are used for light conversion, then emission wavelength adjustment is improved, but power efficiency deteriorates due to light being emitted in all directions including back to the light-emitting element
Solution Approach 1:
The reflective layer inverts the optical path by reflecting unconverted light back toward the wavelength conversion layer. This allows the same quantum dot material to be used more effectively, converting light that would otherwise be wasted and improving power efficiency while maintaining the ability to adjust emission wavelengths through quantum dot size control.
Solution Approach 2:
The patent enables continuous useful action by allowing light to pass through the wavelength conversion layer multiple times. The reflective layer ensures that unconverted light is not lost but continues to interact with the quantum dots, extending the useful conversion process and improving overall power efficiency while maintaining wavelength adjustability.
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 proposed structure significantly enhances light-extraction efficiency, reduces power consumption, and achieves high-quality image display with improved reliability and color reproducibility, addressing the limitations of existing quantum dot-based display devices.
Implementation Method 1
The first light enters the wavelength-conversion layer and the wavelength-conversion layer has a function of emitting second light whose wavelength is longer than that of the first light
Implementation Method 2
The optically functional layer has a function of transmitting the first light and reflecting the second light
Implementation Method 3
The optically functional layer has a function of transmitting the first light and reflecting the second light
Data Source
AI summary
A display device having high light-extraction efficiency is provided. A low-power display device is provided. In a red or green pixel included in the display device, a light-emitting element, an optically functional layer, and a wavelength-conversion layer are stacked in this order. The light-emitting element emits blue light, the optically functional layer transmits the blue light and reflects red and green light, and the wavelength-conversion layer converts the blue light into red or green light. The blue light emitted by the light-emitting element passes through the optically functional layer and enters the wavelength-conversion layer, and red or green light is emitted to the outside. The red or green light emitted from the wavelength-conversion layer to the optically functional layer side is reflected by the optically functional layer and emitted to the outside, which improves light-extraction efficiency.