Quantum Dot Light Emitting Device Grating Wavelength Selection
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Solution Overview
Problem
Current quantum dot light emitting devices face challenges in achieving high-purity color light with narrow emission spectra, as they often result in wide wavelength bands and significant viewing angle dependencies, limiting their efficiency and color consistency.
Innovation Solution
The proposed quantum dot light emitting device incorporates a grating device with specific grating intervals and materials, combined with quantum dot layers of varying sizes, to selectively emit light of multiple wavelength bands, reducing the width of the emission spectrum and enhancing color purity. This is achieved by stacking quantum dot layers between electrodes and using grating regions with different intervals to control the wavelength selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If quantum dot light emitting devices use conventional structures without grating devices, then the device structure is simple, but the emission spectrum is wide and color purity is low
Solution Approach 1:
A grating device is introduced as an intermediary component between the quantum dot layer and the external environment. This grating device mediates the extraction of guided-wave light by providing periodic structures that couple trapped light modes to radiative modes, thereby narrowing the emission spectrum and improving color purity without fundamentally changing the quantum dot emission characteristics
Solution Approach 2:
The invention transitions from considering only the vertical dimension of light extraction to incorporating horizontal periodic structures (gratings) with specific pitch dimensions. By introducing this additional spatial dimension with controlled periodicity, the device achieves wavelength-selective light extraction and improved color purity
2Ease of manufacture
If quantum dot light emitting devices use conventional structures, then the device is easy to manufacture, but viewing angle dependency of emission color is significant
Solution Approach 1:
The grating device serves as an intermediary optical element that modifies the angular distribution of emitted light. By designing gratings with specific pitch values, the device achieves wide viewing angle coverage while maintaining consistent emission color across different viewing angles, as the grating periodically modulates the light extraction in a direction-independent manner
3Device complexity
If quantum dot light emitting devices use single wavelength emission, then the structure is simple, but the application versatility is limited
Solution Approach 1:
The grating device is segmented into multiple regions, each with different pitch values optimized for specific wavelength bands. By dividing the grating structure into first, second, and third grating regions with progressively smaller pitches, the device can selectively extract light from different wavelength ranges (e.g., red, green, blue) simultaneously, enabling full-color display applications
Solution Approach 2:
Different regions of the grating device are assigned different local properties (pitch values) to optimize light extraction for specific wavelength bands. The first grating region has a larger pitch for red light extraction, the second region has a medium pitch for green light, and the third region has a smaller pitch for blue light, allowing each region to perform its specialized function
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 generates high-purity color light with reduced wavelength band widths, improving color consistency and efficiency by selectively emitting specific wavelength bands, making it suitable for advanced display and optical applications.
Implementation Method 1
a cavity structure for resonating light
Implementation Method 2
a periodic structure for extracting guided-wave light generated between reflective surfaces
Implementation Method 3
Quantum dots emit light via electroluminescence or photoluminescence
Implementation Method 4
Quantum dots emit light via electroluminescence or photoluminescence
Implementation Method 5
a periodic structure for extracting guided-wave light generated between reflective surfaces to outside
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A quantum dot light emitting device includes a grating device which includes a grating region that has a particular grating interval, and a quantum dot layer located above the grating region. The device provides high-purity color light based on a selection of a wavelength band by the grating region in correspondence with a wavelength band of light emitted from the quantum dot layer.