Quantum Dot Light-Emitting Element Halogen Concentration Gradient
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Solution Overview
Problem
Current light-emitting elements containing quantum dots face challenges in enhancing light emission efficiency.
Innovation Solution
A light-emitting element configuration with a first quantum dot portion and a second quantum dot portion, where one portion contains halogen elements at a predetermined concentration and the other portion contains either no halogen elements or a lower concentration, is used between the light-emitting layer and the electrodes, optimizing the band gap and carrier balance for improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If quantum dots are used in light-emitting elements, then light emission is achieved, but light emission efficiency is insufficient
Solution Approach 1:
The patent applies local quality by creating two distinct quantum dot portions with different halogen element concentrations within the same light-emitting layer. The first quantum dot portion contains halogen elements at a predetermined concentration to facilitate hole injection and reduce trap states, while the second quantum dot portion contains no halogen elements or lower concentration to maintain electron injection efficiency. This spatial differentiation of chemical composition allows each region to optimize for its specific carrier type, resolving the contradiction between achieving light emission and improving overall efficiency.
Solution Approach 2:
The patent employs parameter changes by systematically varying the halogen element concentration across different quantum dot portions. By controlling the halogen content parameter in the first quantum dot portion (at predetermined concentration) versus the second quantum dot portion (no or lower concentration), the patent optimizes the electronic structure and band alignment for respective carrier injections. This parameter optimization directly addresses the energy loss issue by ensuring efficient carrier recombination at the quantum dots.
2Reliability
If halogen elements are added to quantum dot surface, then surface defects are reduced, but carrier balance becomes difficult to control
Solution Approach 1:
The patent applies segmentation by dividing the quantum dot layer into two functionally distinct portions: a first quantum dot portion with halogen elements for hole injection optimization and surface defect reduction, and a second quantum dot portion without or with lower halogen concentration for electron injection. This segmentation allows independent optimization of hole and electron transport characteristics, simplifying carrier balance control while maintaining surface quality.
Solution Approach 2:
The patent implements local quality by assigning different halogen element concentrations to different spatial regions of the light-emitting layer. The first quantum dot portion localized near the hole injection interface contains halogen elements to passivate surface defects, while the second quantum dot portion localized near the electron injection interface contains minimal halogen to preserve electron mobility. This localized compositional control achieves both surface defect reduction and carrier balance without increasing device complexity.
Data Source
AI summary
A light-emitting element includes the following: a first electrode and a second electrode; a light-emitting layer disposed between the first electrode and the second electrode; and a functional layer disposed between the light-emitting layer and the second electrode, wherein the light-emitting layer has a first quantum dot portion including a first quantum dot, and a second quantum dot portion including a second quantum dot, and disposed between the first quantum dot portion and the functional layer, and one of the first quantum dot portion and the second quantum dot portion contains halogen elements at a predetermined concentration, and the other of the first quantum dot portion and the second quantum dot portion contains no halogen elements or contains halogen elements at a lower concentration than the predetermined concentration.