Quantum Dot Electroluminescent Element Composite Layer Design
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Solution Overview
Problem
Quantum dot electroluminescent elements experience a decrease in light-emitting efficiency as voltage increases, due to electron accumulation and non-radiative recombination processes, leading to reduced brightness and purity of emitted light.
Innovation Solution
A quantum dot electroluminescent element is designed with a composite light-emitting layer comprising two quantum dot light-emitting layers separated by a hole transport and electron blocking intermediate layer, which prevents electron escape at low voltage and allows recombination in the adjacent layer at higher voltages, expanding the recombination region and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If voltage is increased to improve brightness output, then light output increases, but light-emitting efficiency decreases due to electron accumulation and non-radiative recombination
Solution Approach 1:
The single light-emitting layer is divided into multiple quantum dot light-emitting layers with different thicknesses. This segmentation allows electrons to recombine in different layers at different voltage levels, distributing the recombination events across multiple interfaces and reducing electron accumulation in any single layer, thereby maintaining high light-emitting efficiency while achieving desired brightness output.
Solution Approach 2:
Different quantum dot light-emitting layers are designed with different thicknesses to create local variations in electron-hole recombination characteristics. Thinner layers facilitate electron transport and reduce accumulation, while thicker layers provide sufficient recombination zones. This local quality differentiation optimizes the balance between light output and efficiency across the entire device structure.
2Device complexity
If a single quantum dot light-emitting layer is used, then the structure is simple, but electron accumulation occurs at high voltage reducing brightness purity
Solution Approach 1:
The light-emitting structure is segmented into multiple quantum dot light-emitting layers, each contributing to the overall emission. This segmentation prevents electron accumulation by distributing recombination events across multiple layers, thereby maintaining brightness purity even at high voltage operation, while the cumulative effect of multiple layers still provides sufficient light output.
Solution Approach 2:
The problem of electron accumulation in a single layer is solved by adding the dimension of multiple layers stacked in series. This dimensional change transforms a two-dimensional single-layer structure into a three-dimensional multi-layer structure, providing additional spatial zones for electron-hole recombination and preventing charge accumulation that would otherwise degrade brightness purity.
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 enhances light-emitting efficiency by increasing the number of electrons participating in recombination, reducing non-radiative processes, and maintaining high brightness and purity of emitted light across varying voltages.
Implementation Method 1
the intermediate layer is configured to transport holes and block electrons
Implementation Method 2
the intermediate layer is configured to transport holes and block electrons
Implementation Method 3
Quantum dot electroluminescent diode (QLED) is a new electronic element for display applications, which directly injects electrons and holes into quantum dot emitters to achieve electroluminescence
Implementation Method 4
expanding the recombination region and maintaining efficiency
Data Source
AI summary
A quantum dot electroluminescent element, a display panel, and a display device are provided. The quantum dot electroluminescent element includes an anode layer, a composite light-emitting layer, and a cathode layer which are stacked. The composite light-emitting layer includes at least two quantum dot light-emitting layers which are stacked, and an intermediate layer arranged between every two adjacent ones of the at least two quantum dot light-emitting layers; the intermediate layer is configured to transport holes and block electrons.