Performance Enhancement of Pentacene-Based Organic Thin-Film Transistors Using a High-K PVA/Low-K PVP Bilayer as the Gate Insulator

Ching-Lin Fan; Hou-Yen Tsao; Yu-Shien Shiah; Che-Wei Yao; Po-Wei Cheng

doi:10.3390/polym13223941

Performance Enhancement of Pentacene-Based Organic Thin-Film Transistors Using a High-K PVA/Low-K PVP Bilayer as the Gate Insulator

Polymers (Basel). 2021 Nov 15;13(22):3941. doi: 10.3390/polym13223941.

Authors

Ching-Lin Fan^{1

2}, Hou-Yen Tsao¹, Yu-Shien Shiah¹, Che-Wei Yao¹, Po-Wei Cheng¹

Affiliations

¹ Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, 43 Sec. 4, Keelung Road, Taipei 106, Taiwan.
² Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, 43 Sec. 4, Keelung Road, Taipei 106, Taiwan.

Abstract

In this study, we proposed using the high-K polyvinyl alcohol (PVA)/low-K poly-4-vinylphenol (PVP) bilayer structure as the gate insulator to improve the performance of a pentacene-based organic thin-film transistor. The dielectric constant of the optimal high-K PVA/low-K PVP bilayer was 5.6, which was higher than that of the single PVP layer. It resulted in an increase in the gate capacitance and an increased drain current. The surface morphology of the bilayer gate dielectric could be suitable for pentacene grain growth because the PVP layer was deposited above the organic PVA surface, thereby replacing the inorganic surface of the ITO gate electrode. The device performances were significantly improved by using the bilayer gate dielectric based upon the high-K characteristics of the PVA layer and the enlargement of the pentacene grain. Notably, the field-effect mobility was increased from 0.16 to 1.12 cm²/(Vs), 7 times higher than that of the control sample.

Keywords: field-effect mobility; gate dielectric; high-K; organic TFT; pentacene; surface morphology.