Quantum Dot Hole Transport Layer for Photolithography-Stable Displays
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Solution Overview
Problem
The hole transport layer in self-emission display devices is dissolved by developing solutions used in photolithography, leading to inaccurate thickness and degradation in display performance.
Innovation Solution
Incorporating a hole transport material with a predetermined molecular weight or higher into the first hole transport layer, combined with quantum dots, allows for accurate formation of the layer through photolithography, preventing degradation by using a mixed solution forming, dropping, phase separation, exposure, and patterning steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to form the light-emitting layer, then manufacturing precision and definition are improved, but the hole transport layer is dissolved by developing solution causing thickness inaccuracy and performance degradation
Solution Approach 1:
A protective film is introduced as an intermediary layer between the hole transport layer and the developing solution. This protective film acts as a barrier that prevents the developing solution from dissolving the hole transport layer during photolithography processing, while allowing the light-emitting layer to be properly patterned. The protective film is selectively removed after patterning to complete the process.
Solution Approach 2:
The protective film is formed on the hole transport layer before the photolithography process begins. This preliminary protective action ensures that the hole transport layer is shielded from damage during subsequent processing steps, maintaining its thickness and integrity throughout the manufacturing process.
2Ease of manufacture
If liquid-drop method is used to form the light-emitting layer, then manufacturing cost and ease of production are improved, but the hole transport layer is still exposed to developing solution causing thickness variation
Solution Approach 1:
The protective film serves as a mediator that enables the use of liquid-drop methods for forming the light-emitting layer while simultaneously protecting the hole transport layer from the developing solution. This allows manufacturers to benefit from the simplicity and cost-effectiveness of liquid-drop deposition without sacrificing the precision and integrity of the underlying hole transport layer.
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
Ensures accurate thickness of the hole transport layer, preventing display performance degradation even when forming the light-emitting layer through photolithography.
Implementation Method 1
a light-emitting element layer including a plurality of light-emitting elements each including a first electrode, a function layer, and a second electrode, the plurality of light-emitting elements being configured to emit mutually different colors of light
Implementation Method 2
the first hole transport layer contains the quantum dot, and a hole transport material having a predetermined molecular weight or higher
Data Source
AI summary
A display device has a thin film transistor layer, a light-emitting element layer, and an electron transport layer provided on a light-emitting layer. The light-emitting element layer includes a plurality of light-emitting elements each of which includes a first electrode, a function layer, and a second electrode, and that emit mutually different colors of light. A first hole transport layer contains a hole transport material, and the light-emitting layer contains a quantum dot. The first hole transport layer contains the quantum dot, and a hole transport material having a predetermined molecular weight or higher. The light-emitting layer contains the quantum dot and a ligand coordinating with the quantum dot. The first hole transport layer contains the quantum dot coordinating with the ligand. The ligand coordinates with the quantum dot so as to prevent the hole transport material from being exposed to the light-emitting layer.