Quantum Dot Light-Emitting Element Ligand Dipole Gradient
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Solution Overview
Problem
The existing light-emitting elements with quantum dots have a low density of quantum dots towards the anode, leading to decreased exciton formation efficiency and overall light emission efficiency.
Innovation Solution
A light-emitting element with a light-emitting layer comprising a first layer with first quantum dots and a second layer closer to the electron-transport layer, both with different ligands having distinct dipole moments, to enhance quantum dot density and exciton formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the particle size of quantum dots is increased toward the anode to form a potential well, then light emission efficiency improves, but quantum dot density decreases leading to reduced exciton formation efficiency
Solution Approach 1:
The patent applies local quality by using different ligands with different dipole moments in different regions of the light-emitting layer. Specifically, ligands with larger dipole moments are used in the first light-emitting layer (closer to anode) while ligands with smaller dipole moments are used in the second light-emitting layer (closer to cathode), creating spatially varying properties that simultaneously maintain quantum dot density and form potential well
Solution Approach 2:
The patent changes the dipole moment parameter of ligands as a function of position within the light-emitting layer. By gradually varying the ligand dipole moment from smaller values near the cathode to larger values near the anode, the patent creates a continuous potential gradient that maintains quantum dot density while forming the necessary potential well for efficient light emission
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 proposed solution improves the light emission efficiency by maintaining a sufficient quantum dot density towards the anode and optimizing carrier transport and recombination.
Implementation Method 1
a dipole moment of the first ligands is larger than a dipole moment of the second ligands
Implementation Method 2
the particle size of the quantum dots is designed to gradually increase from toward the cathode to toward the anode, thereby forming a potential well
Implementation Method 3
a light-emitting element including a light-emitting layer containing quantum dots
Data Source
AI summary
A light-emitting element includes: a cathode; an anode; a light-emitting layer provided between the cathode and the anode and containing quantum dots; an electron-transport layer provided between the light-emitting layer and the cathode; and a hole-transport layer provided between the light-emitting layer and the anode. The light-emitting layer includes a first light-emitting layer containing first quantum dots to which first ligands are coordinated, and further includes a second light-emitting layer provided closer to the electron-transport layer than to the first light-emitting layer, and containing second quantum dots to which second ligands are coordinated. A dipole moment of the first ligands is larger than a dipole moment of the second ligands.