Quantum Dot Light Emitting Diode Crosslinked Emissive Layer
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Solution Overview
Problem
Current light-emitting devices with quantum dots face challenges in achieving efficient and cost-effective fabrication, particularly in creating multicolor high-resolution displays, as existing methods require complex and costly processes for patterning quantum dots, and there is a need for solvents that do not damage previously deposited layers.
Innovation Solution
A cross-linked layer incorporating quantum dots dispersed in a cross-linked material, which acts as both a charge transport and emissive layer, improving patterned layers and simplifying fabrication by combining properties of charge transport and emissive layers, and allowing for controlled distribution of quantum dots using nucleophilic or electrophilic centers and ligands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal evaporation methods are used for depositing layers, then the quality of OLED layers is improved, but the fabrication complexity and cost increase
Solution Approach 1:
The patent replaces thermal evaporation (a complex physical vapor deposition process) with solution processing methods. The emissive layer is deposited by coating solutions containing quantum dots and crosslinkable materials, followed by UV irradiation to initiate crosslinking. This substitution of mechanical/physical deposition with chemical solution processing simplifies fabrication equipment requirements and reduces costs while maintaining layer quality.
Solution Approach 2:
The patent changes the deposition parameters from thermal evaporation conditions to solution-based coating parameters. By using solutions with specific solvents, quantum dot concentrations, and crosslinkable material ratios, the method achieves high-quality layers through chemical processes rather than thermal physical processes, reducing fabrication complexity.
2Ease of manufacture
If solution process methods are used for fabricating devices, then fabrication cost and simplicity are improved, but solvent selection becomes more critical to avoid damaging previous layers
Solution Approach 1:
The patent introduces a crosslinkable material as an intermediary between the quantum dots and the solvent environment. This material forms a crosslinked network that protects the quantum dot layer from solvent damage, enabling the use of solution processing methods with various solvents without worrying about dissolving or damaging previously deposited layers.
Solution Approach 2:
The patent creates a composite emissive layer combining quantum dots with crosslinkable materials. This composite structure provides both the optoelectronic functionality of quantum dots and the solvent resistance of crosslinked polymers, simplifying solvent selection for subsequent processing steps while maintaining fabrication simplicity.
3Manufacturing precision
If quantum dots are patterned using conventional photolithography and layer by layer assembly, then multicolor display resolution is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges the patterning function with the material deposition step. By incorporating photoresponsive groups directly into the crosslinkable material, the entire emissive layer can be patterned through selective UV irradiation in a single step, eliminating the need for separate photolithography and layer-by-layer assembly processes while maintaining high resolution.
Solution Approach 2:
The patent performs preliminary patterning of the crosslinkable material before quantum dot deposition. The crosslinkable material is selectively crosslinked in desired pixel regions first, creating a patterned scaffold that guides subsequent quantum dot deposition. This preliminary action simplifies the overall patterning process by establishing the pattern framework before adding the emissive quantum dots.
4Reliability
If separate charge transport layer and emissive layer are used, then device performance is improved, but the number of fabrication steps increases
Solution Approach 1:
The patent merges the charge transport layer and emissive layer into a single combined layer. The emissive layer contains quantum dots for light emission and crosslinkable charge transport materials that provide charge transport functionality. This consolidation maintains device performance by ensuring proper charge transport to quantum dots while reducing the number of fabrication deposition steps.
Solution Approach 2:
The patent creates a multi-functional emissive layer that simultaneously performs emission and charge transport functions. The crosslinkable material in the emissive layer provides charge transport capabilities, making the emissive layer universal in its functionality and eliminating the need for a separate charge transport layer, thereby improving fabrication efficiency.
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 cross-linked layer enhances the performance of quantum dot light-emitting devices by improving light-emitting efficiency and simplifying the fabrication process, enabling the creation of high-resolution multicolor displays with improved solvent resistance and patterned layers.
Implementation Method 1
the cross-linkable material is crosslinked to form a crosslinked network in which the quantum dots are dispersed
Implementation Method 2
each region emits light (through charge injection that causes electroluminescence) at three different colors
Data Source
AI summary
A light-emitting device includes an anode, cathode, and a combined charge transport and emissive layer (CCTEL) disposed on a deposition surface between the anode and cathode. The CCTEL includes a crosslinked charge transport material and quantum dots, the quantum dots distributed unevenly within the crosslinked charge transport material and arranged relative to the deposition layer. The quantum dots include nucleophilic or electrophilic centers and ligands respectively bonded to the quantum dots. The deposition surface has nucleophilic or electrophilic properties. A method of forming the CCTEL includes the steps of depositing a mixture on a deposition surface having nucleophilic or electrophilic properties. The mixture includes a solvent, cross-linkable charge transport material, and quantum dots comprising nucleophilic or electrophilic centers and ligands respectively bonded to the quantum dots. At least a portion of the mixture to an activation stimulus to crosslink the cross-linkable material.