Liquid crystal-gated-organic field-effect transistors with in-plane drain-source-gate electrode structure

Area of Science:

• Organic electronics
• Materials science
• Device physics

Background:

• Organic field-effect transistors (OFETs) are crucial for flexible electronics.
• Liquid crystals (LCs) offer unique electro-optic properties for device modulation.

Purpose of the Study:

• To develop and characterize novel planar liquid crystal-gated-organic field-effect transistors (LC-g-OFETs).
• To investigate the influence of poly(3-hexylthiophene) (P3HT) thickness on device performance.
• To elucidate the working mechanism of LC-g-OFETs.

Main Methods:

• Fabrication of LC-g-OFETs using photolithography and spin-coating techniques.
• Utilizing 4-cyano-4′-pentylbiphenyl (5CB) as the liquid crystal layer and P3HT as the semiconductor channel.
• Characterization of transistor performance, including output curves and on/off ratios.

Main Results:

• LC-g-OFETs demonstrated p-type transistor characteristics.
• Achieved current saturation for P3HT layers between 50-150 nm.
• Obtained an on/off ratio exceeding 1 × 10(3) and hole mobility of 0.5-1.1 cm(2)/(V s), dependent on P3HT thickness.

Conclusions:

• The developed LC-g-OFETs are cost-effectively fabricated using standard processes.
• The device performance is tunable via P3HT layer thickness.
• Tilted ordering of the liquid crystal at the interface, induced by the electric field, is key to the device's function.