Polymer Encapsulants for Threshold Voltage Control in Carbon Nanotube Transistors

Area of Science:

• Materials Science
• Electrical Engineering
• Nanotechnology

Background:

• Carbon nanotube transistors (CNTs) offer high performance but face challenges in large-scale uniformity and repeatability for printable electronics.
• Controlling the electrostatic environment is crucial for achieving consistent performance in CNT-based devices.

Purpose of the Study:

• To investigate polymer dielectric encapsulants for controlling the electrostatic environment of CNT transistors.
• To establish a correlation between interfacial charge density and transistor conduction onset.
• To demonstrate a method for balancing p-type and n-type transport and fabricating p-n diodes.

Main Methods:

• Surveyed polymer dielectric encapsulants compatible with printing processes.
• Correlated interfacial charge density with transistor conduction onset.
• Utilized statistical copolymers of poly(styrene-co-2-vinylpyridine) with varying molar fractions.
• Incorporated an electron-donating molecule to balance transport properties.
• Fabricated and characterized a p-n diode.

Main Results:

• A direct correlation was found between interfacial charge density and the onset of conduction in CNT transistors.
• Achieved smooth and continuous balancing of p-type and n-type transport properties.
• Successfully fabricated a p-n diode exhibiting a rectification ratio of 8:1.

Conclusions:

• Controlling interfacial charge density via polymer encapsulants offers a rational route to tune CNT transistor electrical characteristics.
• The developed method enhances uniformity and repeatability for printable electronics applications.
• The study demonstrates the potential for creating functional p-n diodes using this approach.