Green Quantum Dot Emission Stack for Carrier-Balanced Top Emission
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Solution Overview
Problem
In Quantum Dot Light Emitting Diodes (QLEDs), carrier balance is unbalanced due to better electron injection for red and green quantum dot materials compared to hole injection, and weaker electron injection for blue quantum dot materials, limiting efficiency and stability, especially in small-sized display products.
Innovation Solution
A green quantum dot light-emitting device is designed with specific thickness ranges for electron and hole transport layers, including a Zn-based oxide electron transport layer and organic/inorganic hole transport layers, optimized for top emission structure to improve carrier balance and light emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electron transport layers are used in green quantum dot light-emitting devices, then the device structure is simple, but the carrier balance is unbalanced and current efficiency is limited
Solution Approach 1:
The electron transport layer is segmented into multiple sub-layers with different functions: a first electron transport layer (ZnO) for electron injection and transport, and a second electron transport layer (Zn1-xMgxO) for carrier balance and stability. This segmentation allows each layer to be optimized for specific carrier transport needs, resolving the contradiction between maintaining simple structure and achieving balanced carriers.
Solution Approach 2:
The patent uses composite material structure combining ZnO and Zn1-xMgxO in the electron transport layers. ZnO provides high electron mobility for efficient electron injection, while Zn1-xMgxO provides可调 bandgap and LUMO level for balanced carrier transport. This composite approach achieves superior carrier balance without significantly increasing device complexity.
2Reliability
If the electron transport layer thickness is increased to improve electron injection, then electron transport efficiency improves, but the light emitting angle distribution broadens and front-side intensity decreases
Solution Approach 1:
The patent optimizes the thickness parameters of electron transport layers to specific ranges (first layer: 5-15 nm, second layer: 15-30 nm) to achieve the best balance between electron injection efficiency and light emitting angle control. By precisely controlling layer thickness within these ranges, the device achieves narrow light emitting angles and concentrated front-side intensity while maintaining efficient electron transport.
Solution Approach 2:
Different regions of the electron transport structure are assigned different thicknesses and materials: the first electron transport layer closer to the quantum dot layer is thinner (5-15 nm) for efficient electron injection, while the second electron transport layer is thicker (15-30 nm) for carrier balance and light angle control. This local quality differentiation resolves the contradiction between injection efficiency and light concentration.
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 optimized thickness of electron and hole transport layers in the green quantum dot light-emitting device enhances current efficiency, narrows light emitting angle distribution, and concentrates light intensity on the front side, improving overall device performance.
Implementation Method 1
a first electron transport layer between the first cathode and the green quantum dot light-emitting layer, wherein a material of the first electron transport layer includes an oxide containing Zn
Implementation Method 2
a green quantum dot light-emitting layer between the first cathode and the first anode
Implementation Method 3
a first hole transport layer between the green quantum dot light-emitting layer and the first anode
Implementation Method 4
the first cathode includes a reflective film layer
Data Source
AI summary
Embodiments of the present disclosure disclose a green quantum dot light-emitting device, a method for manufacturing the same, and a display apparatus, including: a first cathode and a first anode opposite to each other, a green quantum dot light-emitting layer between the first cathode and the first anode, a first electron transport layer between the first cathode and the green quantum dot light-emitting layer, and a first hole transport layer between the green quantum dot light-emitting layer and the first anode; wherein a material of the first electron transport layer includes an oxide containing Zn, a thickness of the first electron transport layer is in the range of 10 nm to 40 nm, and a thickness of the first hole transport layer is in the range of 26 nm to 39 nm.