Blue Top-Emitting QLED Structure for CIEy Reduction
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Solution Overview
Problem
The luminous efficiency of blue top emitting quantum dot light-emitting devices (QLEDs) is lower than that of red and green QLEDs, and the optical microcavity effect causes the electroluminescence spectrum to be broadened and red-shifted, leading to a reduced color gamut and increased CIEy value, which affects the chromaticity efficiency and display performance.
Innovation Solution
A blue top emitting QLED structure is designed with a ZnSe1-x:Tex/ZnSe/ZnS quantum dot light-emitting layer, where x is 0.03 to 0.07, and specific thicknesses for hole and electron transport layers, along with a hole injection layer, to optimize the microcavity effect and improve chromaticity efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional blue top emitting QLED structure is used, then device structure is simple, but luminous efficiency is low
Solution Approach 1:
The device structure is segmented into multiple functional layers including electron transport layer, hole transport layer, quantum dot light-emitting layer, hole injection layer, and light extraction layer. Each layer performs a specific function to optimize carrier transport and light emission, thereby improving luminous efficiency while maintaining manufacturability through modular design
Solution Approach 2:
The patent optimizes key parameters including the thickness of electron transport layer (25-50 nm), hole transport layer (10-35 nm), and quantum dot layer composition (ZnSe1-x:Tex/ZnSe/ZnS with x=0.03-0.07). These parameter adjustments enhance carrier injection, transport, and recombination efficiency, resulting in improved luminous efficiency
2Ease of manufacture
If conventional QLED structure is used, then manufacturing process is simple, but optical microcavity effect causes spectrum broadening and red-shift
Solution Approach 1:
The patent introduces intermediary layers including electron transport layer, hole transport layer, and light extraction layer that mediate between the quantum dot light-emitting layer and the electrodes. These intermediary layers optimize the optical microcavity effect by controlling carrier distribution and light emission characteristics, thereby preventing spectrum broadening and red-shift while maintaining simple manufacturing processes
Solution Approach 2:
The patent applies local quality optimization by creating specific compositional gradients and thickness variations in different regions of the device. The quantum dot layer has a core-shell structure with ZnSe/ZnS composition, and the transport layers have optimized thicknesses to create favorable local conditions for carrier injection and recombination, resulting in precise control of electroluminescence spectrum
3Device complexity
If conventional structure is used, then device complexity is low, but chromaticity efficiency is reduced due to increased CIEy value
Solution Approach 1:
The device is segmented into multiple specialized layers including electron transport layer, hole transport layer, quantum dot light-emitting layer, hole injection layer, and light extraction layer. Each layer is optimized for its specific function to improve chromaticity efficiency by controlling carrier transport and light emission characteristics, thereby reducing CIEy value while maintaining acceptable device complexity
Solution Approach 2:
The patent employs composite material structures including the core-shell quantum dot structure (ZnSe/ZnS) and composite transport layers. These composite materials enable precise control of optical and electrical properties to improve chromaticity efficiency and reduce CIEy value
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 structure enhances the chromaticity efficiency to 72.5, improving the device performance by reducing the CIEy value and enhancing current efficiency, making it suitable for high-resolution displays.
Implementation Method 1
a blue quantum dot light-emitting layer between the cathode and the anode... a luminescence peak of an electroluminescence spectrum corresponding to a maximum luminous intensity of the blue top emitting quantum dot light-emitting device is 460 nm
Implementation Method 2
high luminous quantum efficiency... a luminescence peak of a photoluminescence spectrum corresponding to a maximum luminous intensity of the blue quantum dot light-emitting layer is 455 nm
Data Source
AI summary
A blue top emitting quantum dot light-emitting device and a display apparatus are disclosed. The blue top emitting quantum dot light-emitting device includes: a cathode and an anode oppositely arranged, a blue quantum dot light-emitting layer between the cathode and the anode, an electron transport layer between the cathode and the blue quantum dot light-emitting layer, and a hole transport layer between the blue quantum dot light-emitting layer and the anode; where: a material of the blue quantum dot light-emitting layer is ZnSe1-x:Tex/ZnSe/ZnS, ZnSe1-x:Tex means that a molar ratio of Se to Te is 1-x:x, and x is 0.03 to 0.07; a thickness of the hole transport layer is 10 nm to 35 nm, a thickness of the electron transport layer is 25 nm to 50 nm, and a sum of thicknesses of the hole transport layer and the electron transport layer is 55 nm to 65 nm.