Polyimide Thin Film with Ester Groups for OLED Substrates
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Solution Overview
Problem
Current flexible substrate materials for OLEDs face challenges in achieving high levels of optical transparency, heat resistance, and thermal dimensional stability, limiting their comprehensive performance.
Innovation Solution
A polyimide thin film with a specific structural formula and a two-step preparation method involving a dianhydride and fluorodiamine reaction, followed by spin-coating and baking, is developed to enhance heat resistance and flexibility, incorporating ester groups and aromatic rings for improved thermal stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If plastic substrate materials are used for flexibility, then film formability and flexibility are improved, but heat resistance and thermal dimensional stability deteriorate
Solution Approach 1:
The patent uses polyimide as a composite material that combines the flexibility needed for flexible substrates with inherent heat resistance properties, resolving the contradiction between flexibility and heat resistance by selecting a material that possesses both characteristics simultaneously
Solution Approach 2:
The patent optimizes the molecular weight parameters of polyimide (specifically controlling the weight average molecular weight and polydispersity index) to achieve the desired balance between flexibility and heat resistance, demonstrating parameter changes as an inventive principle
2Temperature
If polyimide molecular weight is increased for heat resistance, then thermal stability is improved, but film formation and flexibility deteriorate
Solution Approach 1:
The patent precisely controls the molecular weight parameters (weight average molecular weight between 200,000-400,000 and polydispersity index between 1.05-1.30) to achieve optimal balance between thermal stability and film flexibility, showing how parameter optimization resolves the technical contradiction
Solution Approach 2:
The patent replaces mechanical mixing methods with ultrasonic wave irradiation during the polyimide preparation process, which enables better molecular weight control and more uniform film formation while maintaining thermal stability, demonstrating mechanics substitution as an inventive principle
3Ease of manufacture
If conventional polyimide preparation methods are used, then manufacturing simplicity is maintained, but comprehensive performance (optical transparency, heat resistance, thermal dimensional stability) deteriorates
Solution Approach 1:
The patent replaces conventional mechanical stirring with ultrasonic wave irradiation in the polyimide preparation process, which improves molecular weight control and film uniformity while maintaining ease of manufacture, resolving the contradiction between manufacturing simplicity and comprehensive performance
Solution Approach 2:
The patent develops a polyimide preparation method that simultaneously achieves multiple performance requirements (optical transparency, heat resistance, thermal dimensional stability, and flexibility) through a unified process using ultrasonic waves, demonstrating multi-functionality as an inventive principle
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 polyimide thin film exhibits enhanced heat resistance and flexibility, with a weight loss of 1% at 590°C and a deformation rate of less than 2 ppm/K from 50-350°C, suitable for use in OLED substrates, providing thermal stability and flexibility for display devices.
Implementation Method 1
a weight loss of 1% at 590°C
Implementation Method 2
a deformation rate of less than 2 ppm/K from 50-350°C
Data Source
AI summary
The present disclosure provides a polyimide thin film, a preparing method thereof, and a display device. Specifically, a polyamic acid containing an ester group structure is prepared. The polyamic acid is prepared by a two-step process. A dianhydride containing an ester group structure is introduced into a polyimide to increase the content of benzene ring. Moreover, the introduction of ester groups is conducive to flexibility, which not only improves its heat resistance component, but, by introducing components with longer flexible chains, effectively destroys the regularity of macromolecules, thereby improving the flexibility of the material. Moreover, the introduction of rigid aromatic ring groups facilitates the realization of heat resistance. The ester bond is introduced into the dianhydride through the esterification, and then participates in the preparing of the polyimide material.