Quantum-dot electroluminescent device single-layer white light
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Solution Overview
Problem
Current quantum-dot electroluminescent devices require a complex multilayer structure to emit white light, leading to high costs and varying chromaticity with voltage, necessitating a simpler structure with high luminous efficiency.
Innovation Solution
A quantum-dot electroluminescent device with a single light-emitting layer composed of a thermally activated delayed fluorescence material and a quantum-dot light-emitting material, which mix to emit white light, enhancing luminous efficiency and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a multilayer structure with three primary color emitting layers is used to emit white light, then the chromaticity can be controlled, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges the functions of three separate primary color emitting layers (red, green, blue) into a single light-emitting layer containing quantum dots with multiple size distributions. Different sized quantum dots emit different colors when excited by the same blue light source, achieving white light emission with a single layer structure, thus resolving the contradiction between chromaticity control and device complexity
Solution Approach 2:
The patent uses composite quantum dot materials with different core sizes and compositions (e.g., CdSe quantum dots with ZnS shell) in a single light-emitting layer. The composite structure of multiple quantum dot types with varying emission wavelengths allows white light generation from one layer, eliminating the need for complex multilayer stacking while maintaining chromaticity stability
2Stability of the object's composition
If a multilayer structure with three primary color emitting layers is used to emit white light, then the chromaticity can be controlled, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple quantum dot types with different emission colors into a single light-emitting layer, reducing the number of manufacturing steps from three separate layer depositions to one single layer fabrication process. This merging approach significantly lowers manufacturing cost while maintaining chromaticity control through precise quantum dot size and composition engineering
Solution Approach 2:
The patent controls chromaticity by adjusting parameters of quantum dots such as size, composition, and concentration within the single light-emitting layer, rather than through complex multilayer structures. By changing quantum dot parameters (e.g., size distribution, shell thickness), the emission spectrum can be tuned to achieve stable white light with simplified manufacturing and lower cost
3Device complexity
If a single light-emitting layer with quantum dots is used, then the device complexity is reduced, but the luminous efficiency needs to be improved
Solution Approach 1:
The patent introduces a shell layer (e.g., ZnS) as an intermediary around the quantum dot core. This shell acts as a protective barrier that reduces non-radiative recombination and prevents surface defects, thereby significantly improving the photoluminescence quantum yield and overall luminous efficiency of the quantum dots in the single light-emitting layer structure
Solution Approach 2:
The patent employs composite quantum dot structures with core-shell architecture (e.g., CdSe core with ZnS shell) where the shell material has higher bandgap energy than the core. This composite structure confines excitons within the core and provides surface passivation, reducing energy loss and enhancing luminous efficiency while maintaining the simplicity of a single light-emitting layer design
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 device achieves white light emission with improved luminous efficiency by using a single light-emitting layer, reducing complexity and costs, and allowing for adjustable color emission through varying doping ratios and applied voltages.
Implementation Method 1
the light-emitting layer is made of a thermally activated delayed fluorescence material and a quantum-dot light-emitting material which are capable of emitting white light by mixing together in proportion in case of excitation
Implementation Method 2
the thermally activated delayed fluorescence material is capable of emitting blue light and exciting the quantum-dot light-emitting material to emit red and green light
Implementation Method 3
the quantum-dot light-emitting material is made of CdSe/ZnS or ZnSe:Cu2+
Implementation Method 4
solving a thermally activated delayed fluorescence material and a quantum-dot light-emitting material in an organic solution, spin-coating a mixed solution on the hole transport layer
Data Source
AI summary
The present disclosure provides a quantum-dot electroluminescent device, including a light-emitting layer, wherein the light-emitting layer is made of a thermally activated delayed fluorescence material and a quantum-dot light-emitting material which are capable of emitting white light by mixing together in proportion in case of excitation.