Light-Emitting Device With Segmented Exciton Generation Layer
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Solution Overview
Problem
Existing light-emitting devices with quantum dots in the light-emitting layer suffer from reduced luminous efficiency and shortened light emission lifetime due to exciton generation within the layer and the ease of impurity entry during application-based layer formation.
Innovation Solution
A light-emitting device configuration with a separate exciton generation layer and light-emitting layer, where quantum dots are dispersed in the exciton generation layer and phosphors or phosphorescent members are dispersed in the light-emitting layer, with the layers stacked vertically, and formed using vapor deposition to minimize impurity entry and enhance energy transfer through the Förster mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If quantum dots are placed in the light-emitting layer, then light emission is achieved, but luminous efficiency is reduced due to exciton generation within the layer
Solution Approach 1:
The device divides the light-emitting layer into two separate functional layers: an exciton generation layer containing quantum dots and a light-emitting layer containing phosphors. This segmentation allows excitons to be generated in one layer and transferred to another, preventing energy loss from direct exciton generation in the phosphor layer and improving overall luminous efficiency.
2Ease of manufacture
If the light-emitting layer is formed by applying, then manufacturing is easier, but impurities easily enter and light emission lifetime is shortened
Solution Approach 1:
The patent employs vapor deposition techniques to form the light-emitting layer in a controlled vacuum or inert atmosphere environment. This prevents impurity contamination during layer formation that would occur with application methods, thereby extending the light emission lifetime while maintaining manufacturing feasibility through established vapor deposition processes.
3Device complexity
If quantum dots and phosphors are in the same layer, then device structure is simpler, but energy transfer efficiency is reduced
Solution Approach 1:
By separating quantum dots and phosphors into adjacent vertical layers, the patent optimizes energy transfer through controlled proximity. The exciton generation layer and light-emitting layer are positioned to maximize Förster resonance energy transfer while maintaining distinct functional zones, achieving high energy transfer efficiency without requiring mixed-material layers.
Solution Approach 2:
The patent introduces a host material matrix that serves as an intermediary medium between quantum dots and phosphors. This host material facilitates efficient energy transfer from excitons in the quantum dot layer to phosphors in the light-emitting layer, enabling effective energy coupling while maintaining structural organization and preventing direct contact that would reduce transfer efficiency.
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
This configuration achieves higher light emission efficiency and longer device lifetime by separating exciton generation and light emission processes, reducing impurity impact and optimizing energy transfer.
Implementation Method 1
optimizing energy transfer through the Förster mechanism
Data Source
AI summary
To provide a light-emitting device for achieving fluorescence emission with higher efficiency and longer life, a light-emitting device includes an exciton generation layer in which quantum dots are dispersed, a light-emitting layer in which light emitters, which are phosphors or phosphorescent members, are dispersed, the light-emitting layer adjoining the exciton generation layer in a vertical direction, a first electrode located on a lower side of the exciton generation layer and the light-emitting layer, and a second electrode located on an upper side of the exciton generation layer and the light-emitting layer, and the light emission spectrum of the quantum dots and the absorption spectrum of the light emitters at least partially overlap.