Enhancing TIPS-Pentacene Organic Thin Film Transistor Performance Through High-k PVP Dielectrics and Direct-Written Silver Nanoparticle Electrodes on PET Substrate Toward Flexible Electronics

As the global demand for printed electronics and wearable devices accelerates, significant efforts have focused on advancing fabrication methods for organic thin film transistors (OTFTs). Inkjet printing, a widely explored approach, offers low-cost, low-temperature processing, and compatibility with flexible substrates. Nevertheless, nozzle clogging and stringent ink and substrate requirements continue to hinder material versatility and large-scale commercialization of OTFTs. Meanwhile, Oxide-based dielectrics, particularly Silicon Dioxide (SiO2), have been extensively used owing to their favorable electrical insulating properties. However, their inherently low gate capacitance density results in high operating voltages, restricting OTFTs from realizing their full potential in practical applications. This work introduces a direct, solution-processable method for fabricating low-voltage OTFTs. Direct-write printing was employed to pattern the source, drain, and gate electrodes, while spin-coating was utilized for depositing both a TIPS-pentacene semiconducting layer and a polyvinylpyrrolidone (PVP) high-k dielectric. The fabricated device featured a 120~\mu m channel length, demonstrating a saturation mobility of 0.686 cm2/Vs, threshold voltage of–3.5 V, an on/off current ratio of 10^{6}, and a subthreshold swing of 105.9 mV/decade. Notably, the entire process was conducted below 150~^{\circ }, and the devices operated at voltages under–5 V. These results highlight direct-write printing with high-k dielectrics as a promising approach for realizing flexible, low-voltage OTFTs, offering a scalable solution for emerging printed electronic systems.