Core-Shell Quantum Dot Light Emitting Element for OLED Efficiency
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Solution Overview
Problem
Conventional organic light emitting diode (OLED) display devices face challenges with high driving voltage, low luminance, and short lifespan due to inefficient hole injection into the emission layer, leading to an imbalance between electrons and holes.
Innovation Solution
A light emitting element is designed with a core/shell quantum dot structure in the emission layer, where the shell has a higher Mg content than the core, and a hole transport layer with a p-type dopant, ensuring similar energy levels for efficient hole injection, and an electron transport layer for balanced electron injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional OLED emission layer is used, then device structure is simple, but hole injection is inefficient and luminous efficiency is low
Solution Approach 1:
The emission layer uses a composite structure combining core quantum dots with a shell layer, where the core contains ZnSe and the shell contains ZnS. This composite material structure improves hole injection efficiency and luminous efficiency while maintaining appropriate energy levels, resolving the contradiction between efficiency improvement and structural complexity.
2Reliability
If conventional emission layer without energy level matching is used, then device complexity is low, but hole injection efficiency is poor and lifespan is short
Solution Approach 1:
The invention changes the energy level parameters of the emission layer by selecting specific quantum dot materials (ZnSe core with ZnS shell) whose energy levels are matched to the hole transport layer. This parameter optimization ensures efficient hole injection and balanced electron-hole recombination, extending device lifespan while requiring precise energy level configuration.
3Illumination intensity
If conventional quantum dot structure with uniform composition is used, then manufacturing is simple, but electron-hole balance is poor and luminance is low
Solution Approach 1:
The quantum dot structure employs local quality differentiation with a ZnSe core and ZnS shell, where each layer has distinct compositional and functional properties. The core provides appropriate band gap while the shell improves hole injection, creating local optimization that enhances luminance through better electron-hole balance while requiring multi-layer manufacturing.
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 stability and emission efficiency by ensuring balanced injection of holes and electrons, resulting in improved luminous efficiency and extended lifespan of the OLED display device.
Implementation Method 1
an emission layer between the first electrode and the second electrode, the emission layer including quantum dots
Implementation Method 2
The quantum dots include a core and a shell. Each of the core and the shell includes at least two selected from Mg, Zn, Te, Se, and S
Implementation Method 3
the hole transport layer including a compound comprising a p-type dopant. The p-type dopant may include at least one of a metal and a halogen element
Data Source
AI summary
A light emitting element includes a first electrode, a second electrode overlapping the first electrode, and an emission layer between the first electrode and the second electrode, the emission layer including quantum dots. The quantum dots include a core and a shell. Each of the core and the shell includes at least two selected from Mg, Zn, Te, Se, and S. When the quantum dots include Mg, a content of Mg in the shell is greater than a content of Mg in the core.