Stability Study of Flexible 6,13-Bis(triisopropylsilylethynyl)pentacene Thin-Film Transistors with a Cross-Linked Poly(4-vinylphenol)/Yttrium Oxide Nanocomposite Gate Insulator.

Jin-Hyuk Kwon,Jaehoon Park,Hyoung Choi,Jin-Hyuk Bae,Shang Piao,Xue Zhang

doi:10.3390/polym8030088

Jin-Hyuk Kwon, Jaehoon Park + Show 4 more

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https://doi.org/10.3390/polym8030088

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Abstract

We investigated the electrical and mechanical stability of flexible 6,13-bis(triisopropylsilylehtynyl)pentacene (TIPS-pentacene) thin-film transistors (TFTs) that were fabricated on polyimide (PI) substrates using cross-linked poly(4-vinylphenol) (c-PVP) and c-PVP/yttrium oxide (Y2O3) nanocomposite films as gate insulators. Compared with the electrical characteristics of TIPS-pentacene TFTs with c-PVP insulators, the TFTs with c-PVP/Y2O3 nanocomposite insulators exhibited enhancements in the drain current and the threshold voltage due to an increase in the dielectric capacitance. In electrical stability experiments, a gradual decrease in the drain current and a negative shift in the threshold voltage occurred during prolonged bias stress tests, but these characteristic variations were comparable for both types of TFT. On the other hand, the results of mechanical bending tests showed that the characteristic degradation of the TIPS-pentacene TFTs with c-PVP/Y2O3 nanocomposite insulators was more critical than that of the TFTs with c-PVP insulators. In this study, the detrimental effect of the nanocomposite insulator on the mechanical stability of flexible TIPS-pentacene TFTs was found to be caused by physical adhesion of TIPS-pentacene molecules onto the rough surfaces of the c-PVP/Y2O3 nanocomposite insulator. These results indicate that the dielectric and morphological properties of polymeric nanocomposite insulators are significant when considering practical applications of flexible electronics operated at low voltages.

Highlights

Over the last few decades, organic thin-film transistors (TFTs) have been extensively studied as candidates for next-generation electronics, because of their simple and large-area applicable processing, low manufacturing cost, light weight, and mechanical flexibility [1,2,3]
The relatively high operating voltage of organic TFTs, which comes from their use of low dielectric polymer gate insulators, has been regarded as an impediment to their commercialization
Most high-k materials that are suitable for organic TFTs are processed via deposition techniques and sol-gel methods and require high processing temperatures that are not suitable for plastic substrate application

Summary

Introduction

Over the last few decades, organic thin-film transistors (TFTs) have been extensively studied as candidates for next-generation electronics, because of their simple and large-area applicable processing, low manufacturing cost, light weight, and mechanical flexibility [1,2,3]. The relatively high operating voltage of organic TFTs, which comes from their use of low dielectric polymer gate insulators, has been regarded as an impediment to their commercialization. Ceramic-based inorganic materials with a high dielectric constant (high-k) can be used as a way to lower the operating voltage of organic TFTs [7,8,9]. Most high-k materials that are suitable for organic TFTs are processed via deposition techniques and sol-gel methods and require high processing temperatures that are not suitable for plastic substrate application. In order to solve this problem, some research groups have devised the use of nanocomposite insulators that can be formed by annealing high-k nanoparticle blended polymer solutions at a relatively low temperature [10,11,12]

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