Quantum Dot Ligands for Photolithographic Display Patterning
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Solution Overview
Problem
Existing methods for forming quantum dot light emitting layers in display apparatuses, such as transfer printing and inkjet techniques, face issues with reliability, process time, and difficulty in achieving high resolution.
Innovation Solution
A quantum dot with a ligand comprising a first repeating unit with hole transporting functional groups and a second repeating unit with photocrosslinkable functional groups, allowing the formation of a light emitting layer through photolithography, which includes a photolithography process that enhances reliability and reduces process time while achieving high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transfer printing technique is used to form quantum dot light emitting layer, then the layer can be formed on substrate, but the solidified layer may be destroyed during physical contact process and reliability is reduced
Solution Approach 1:
The patent replaces the mechanical transfer printing process with a photolithography-based chemical patterning process. The quantum dot layer is formed by applying a solution containing quantum dots with photoreactive ligands, then using light exposure and chemical etching to define patterns. This eliminates mechanical contact that could damage the layer while maintaining manufacturing capability.
Solution Approach 2:
The patent introduces photoreactive ligands as intermediaries that enable pattern formation through light-induced chemical reactions. These ligands mediate between the quantum dots and the patterning process, allowing precise pattern definition without mechanical contact. The ligands contain photoreactive groups that crosslink upon light exposure, enabling selective etching to form the desired pattern.
2Productivity
If inkjet technique is used to form quantum dot light emitting layer, then the layer can be deposited, but the density changes as solvent dries making it difficult to secure light efficiency and process time increases
Solution Approach 1:
The patent replaces the inkjet deposition process with a spin-coating or similar solution application method followed by photolithography. This allows for more uniform solvent distribution and controlled drying, preventing density variations. The photolithography step then precisely defines the pattern, ensuring high light efficiency and reducing overall process time.
Solution Approach 2:
The patent modifies the chemical parameters of the quantum dot solution by incorporating photoreactive ligands with specific photoreactive groups. These ligands change their chemical state upon light exposure, enabling precise pattern formation. The solution composition and drying conditions are optimized to maintain uniform density while enabling rapid processing.
3Manufacturing precision
If transfer printing or inkjet technique is used, then quantum dot layer can be formed, but it is difficult to implement high resolution patterning
Solution Approach 1:
The patent replaces mechanical transfer printing and inkjet printing with a photolithography-based chemical patterning system. This uses light exposure through photomasks and chemical etching to achieve high-resolution patterns. The resolution is determined by the photomask precision and light wavelength rather than mechanical positioning accuracy, enabling superior pattern definition.
4Reliability
If conventional quantum dot methods are used, then layer formation is possible, but process time is excessive and cannot achieve excellent reliability and high resolution simultaneously
Solution Approach 1:
The patent implements a continuous photolithography process where the quantum dot solution with photoreactive ligands is applied, then immediately exposed to light and etched to form the pattern. This continuous chemical process eliminates the discrete mechanical steps of transfer printing or inkjet printing, reducing total process time while maintaining high reliability and resolution.
Solution Approach 2:
The patent incorporates photoreactive ligands into the quantum dot structure in advance, before the patterning step. This preliminary incorporation of functional groups enables the quantum dots to self-pattern through light exposure, eliminating the need for separate layer transfer or deposition steps and significantly reducing overall process time.
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 photolithography process using the quantum dot ligand enables the formation of a reliable and high-resolution light emitting layer, resulting in a display apparatus with improved efficiency and reduced manufacturing time.
Implementation Method 1
the second repeating unit includes one or more photocrosslinkable functional groups
Implementation Method 2
Quantum dots can be applied to the display field using a photo-luminescence phenomenon
Data Source
AI summary
The quantum dot comprises a ligand which is a copolymer comprising a first repeating unit comprising at least one or more hole transporting functional groups and a second repeating unit comprising at least one or more photocrosslinking functional groups.