*Article* **Preparation and Application of Organic-Inorganic Nanocomposite Materials in Stretched Organic Thin Film Transistors**

**Yang-Yen Yu 1,2,\* and Cheng-Huai Yang <sup>1</sup>**


Received: 15 March 2020; Accepted: 2 May 2020; Published: 5 May 2020

**Abstract:** High-transparency soluble polyimide with COOH and fluorine functional groups and TiO2-SiO<sup>2</sup> composite inorganic nanoparticles with high dielectric constants were synthesized in this study. The polyimide and inorganic composite nanoparticles were further applied in the preparation of organic-inorganic hybrid high dielectric materials as the gate dielectric for a stretchable transistor. The optimal ratio of organic and inorganic components in the hybrid films was investigated. In addition, Jeffamine D2000 and polyurethane were added to the gate dielectric to improve the tensile properties of the organic thin film transistor (OTFT) device. PffBT4T-2OD was used as the semiconductor layer material and indium gallium liquid alloy as the upper electrode. Electrical property analysis demonstrated that the mobility could reach 0.242 cm<sup>2</sup> ·V −1 ·s <sup>−</sup><sup>1</sup> at an inorganic content of 30 wt.%, and the switching current ratio was 9.04 <sup>×</sup> <sup>10</sup><sup>3</sup> . After Jeffamine D2000 and polyurethane additives were added, the mobility and switching current could be increased to 0.817 cm<sup>2</sup> ·V −1 ·s <sup>−</sup><sup>1</sup> and 4.27 <sup>×</sup> <sup>10</sup><sup>5</sup> for Jeffamine D2000 and 0.562 cm<sup>2</sup> ·V −1 ·s <sup>−</sup><sup>1</sup> and 2.04 <sup>×</sup> <sup>10</sup><sup>5</sup> for polyurethane, respectively. Additives also improved the respective mechanical properties. The stretching test indicated that the addition of polyurethane allowed the OTFT device to be stretched to 50%, and the electrical properties could be maintained after stretching 150 cycles.

**Keywords:** soluble polyimide; polyurethane; Jeffamine; organic-inorganic hybrid film; Stretchable transistor
