High-mobility ZnO nanorod field-effect transistors by self-alignment and electrolyte-gating

Area of Science:

• Materials Science
• Nanotechnology
• Electronics Engineering

Background:

• Flexible electronics require high-performance transistors.
• Solution-processed semiconductors offer a pathway to low-cost, large-area fabrication.
• Achieving ordered nanostructures is crucial for enhancing charge transport.

Purpose of the Study:

• To demonstrate the alignment of colloidal zinc oxide (ZnO) nanorods using a solvent evaporation technique.
• To investigate the effect of nanorod alignment on the performance of field-effect transistors (FETs).
• To achieve high electron mobilities in solution-processed ZnO FETs for flexible electronics.

Main Methods:

• Colloidal ZnO nanorods were synthesized.
• A solvent evaporation technique was employed to align the ZnO nanorods.
• Field-effect transistors were fabricated using aligned ZnO nanorod films and electrolyte-gating with ionic liquids.

Main Results:

• The degree of nanorod alignment was controlled by varying nanorod length, concentration, and solvent evaporation rate.
• Electron mobility in FETs showed a strong dependence on the degree of alignment.
• Maximum field-effect mobilities reached up to 9 cm² V⁻¹ s⁻¹ for optimally aligned ZnO nanorods.
• Low process temperatures (150 °C) allow for fabrication on flexible polymer substrates.

Conclusions:

• Solvent evaporation is an effective method for aligning ZnO nanorods.
• Optimized alignment of ZnO nanorods significantly enhances electron mobility in FETs.
• These findings support the use of ZnO nanorod thin films for high-performance flexible electronic devices.