Investigation of photo-induced change of electro-optical performance in a liquid crystal-organic field effect transistor (LC-OFET)

Abstract

This study aimed to improve the electrical characteristics of poly(3-hexylthiophene) (P3HT) and liquid crystal-organic field effect transistors (LC-OFETs) under UV illumination. Consequently, a novel LC-OFET was fabricated using a nematic liquid crystal (E63) and a P3HT mixture in an OFET cell. Cell thickness was determined through field emission scanning electron microscopy. For assessment of the electrical characteristics, the LC-OFET device was exposed to various UV light intensities in total darkness for the purpose of obtaining the output- and transfer-current voltage. The capacitance–frequency plot of the capacitor cell was then measured to determine the main parameters including the threshold voltage (V_Th), field effect mobility (μ_FET) and current on/off ratio (I_on/off) of the device. Thus, the full characterisation and UV light response of the electronic parameters were determined for this new class of transistors. Results showed that the new LC-OFET exhibited good performance in the form of low V_Th, high μ_FET, and high I_on/off.

Keywords:

• Photo induced effect
• liquid crystals
• anisotropy
• mobility
• organic materials
• LC-OFET
• OFET
• dipole