Photo-Cross-Linked Polyimide Dielectric for Mechanically Reliable High-Performance Flexible Metal Oxide Thin-Film...

Area of Science:

• Materials Science
• Electrical Engineering
• Polymer Chemistry

Background:

• Flexible high-performance thin-film transistors (TFTs) require reliable dielectric layers that maintain insulation under mechanical stress.
• Oxide semiconductors offer high mobility but pose challenges for dielectric integration in flexible devices.

Purpose of the Study:

• To investigate the suitability of a photo-cross-linkable photosensitive polyimide (PSPI), specifically 6FDA/DABC, as a dielectric layer in flexible oxide TFTs.
• To evaluate the electrical and mechanical reliability of the PSPI dielectric under various conditions.

Main Methods:

• Fabrication of oxide TFTs using zinc tin oxide or indium gallium zinc oxide channel materials and a 6FDA/DABC PSPI dielectric.
• Characterization of the PSPI dielectric's electrical properties, including capacitance, leakage current, and breakdown field.
• Assessment of the dielectric's stability under repeated mechanical bending cycles and bias stress.

Main Results:

• The photo-cross-linked PSPI dielectric showed high areal capacitance (17.5 nF cm^-2), ultralow leakage current (10^-10 A cm^-2), and high breakdown field (>6.7 MV cm^-1).
• The dielectric maintained low leakage and structural integrity after 10,000 bending cycles.
• The resulting TFTs achieved high mobility (15.5 cm² V^-1·s^-1), a high on/off ratio (1.5 × 10⁹), and good bias stress stability.

Conclusions:

• Photo-cross-linked 6FDA/DABC PSPI is a promising dielectric material for high-performance flexible TFTs.
• The developed dielectric ensures stable electrical performance and mechanical reliability under repeated deformation.
• This work confirms the potential of PSPI-based dielectrics for advanced flexible electronic applications.