Quantum Dot Device Dual Hole Auxiliary Layer Structure
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Solution Overview
Problem
Current quantum dot devices face limitations in achieving improved performance due to inefficiencies in hole transport and electron blocking, leading to reduced luminance and lifespan characteristics.
Innovation Solution
Incorporating a dual hole auxiliary layer structure with specific energy level differences and bandgap energies, along with a blended mixture of semiconductor polymers, to enhance hole transport and block excess electrons, thereby improving the quantum dot device's electrical and light-emitting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hole auxiliary layer is used, then the device structure is simple, but hole transport efficiency is insufficient
Solution Approach 1:
The hole auxiliary layer is divided into two distinct layers: a first hole auxiliary layer closer to the light emitting layer and a second hole auxiliary layer closer to the electrode. This segmentation allows each layer to be optimized for specific functions - the first layer for hole injection and the second layer for hole transport - thereby resolving the contradiction between structural simplicity and transport efficiency.
2Ease of manufacture
If hole auxiliary materials with insufficient energy level difference are used, then the material selection is easy, but electron blocking capability is weak
Solution Approach 1:
The patent specifies precise energy level parameters for the hole auxiliary materials: the HOMO energy level difference between the first and second hole auxiliary layers is controlled at 0.1-0.8 eV, and the LUMO energy level difference is controlled at 0.3-1.0 eV. By controlling these energy level parameters, the patent achieves effective electron blocking while maintaining reasonable material selection flexibility.
3Reliability
If the HOMO energy level difference between hole auxiliary materials is too large, then electron blocking is improved, but hole injection efficiency decreases
Solution Approach 1:
The patent optimizes the HOMO energy level difference parameter to be within 0.1-0.8 eV between the first and second hole auxiliary layers. This parameter optimization ensures that the energy barrier is sufficient for electron blocking while remaining low enough to allow efficient hole injection, thus resolving the contradiction between these two opposing requirements.
4Reliability
If a dual hole auxiliary layer structure is implemented, then hole transport and electron blocking are improved, but device complexity increases
Solution Approach 1:
The hole auxiliary function is segmented into two layers with distinct roles: the first hole auxiliary layer (closer to the light emitting layer) primarily handles hole injection, while the second hole auxiliary layer (closer to the electrode) primarily handles hole transport. This functional segmentation improves overall device performance while keeping each individual layer relatively simple.
Solution Approach 2:
Each hole auxiliary layer is designed to perform multiple functions: both layers contribute to hole transport, both layers contribute to electron blocking, and together they create a synergistic effect that improves luminance and lifespan characteristics. This multi-functionality justifies the increased structural complexity.
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 dual hole auxiliary layer structure effectively increases hole mobility and blocks excess electrons, resulting in improved luminance and extended lifespan of quantum dot devices while reducing hysteresis and current instability.
Implementation Method 1
a first hole auxiliary layer between the first electrode and the light emitting layer, wherein the first hole auxiliary layer includes a first hole auxiliary material and a second hole auxiliary material
Implementation Method 2
a difference between a highest occupied molecular orbital (HOMO) energy level of the second hole auxiliary material and a HOMO energy level of the first hole auxiliary material is greater than or equal to about 0.1 electronvolts (eV) and less than about 0.8 eV
Data Source
AI summary
A quantum dot quantum dot device includes a first electrode and a second electrode, a light emitting layer disposed between the first electrode and the second electrode and including quantum dots, and a first hole auxiliary layer between the first electrode and the light emitting layer, wherein the first hole auxiliary layer includes a first hole auxiliary material and a second hole auxiliary material having a greater bandgap energy than a bandgap energy of the first hole auxiliary material, a difference between a HOMO energy level of the second hole auxiliary material and a HOMO energy level of the first hole auxiliary material is about 0.1 eV and less than about 0.8 eV, and a difference between a LUMO energy level of the second hole auxiliary material and a LUMO energy level of the first hole auxiliary material is greater than or equal to about 0.3 eV.