Fabrication and characterization of polyterpenol as an insulating layer and incorporated organic field effect transistor

A non-synthetic polymer material, polyterpenol, was fabricated using a dry polymerization process namely RF plasma polymerization from an environmentally friendly monomer and its surface, optical and electrical properties investigated. Polyterpenol films were found to be transparent over the visible wavelength range, with a smooth surface with an average roughness of less than 0.4 nm and hardness of 0.4 GPa. The dielectric constant of 3.4 for polyterpenol was higher than that of the conventional polymer materials used in the organic electronic devices. The non-synthetic polymer material was then implemented as a surface modification of the gate insulator in field effect transistor (OFET) and the properties of the device were examined. In comparison to the similar device without the polymer insulating layer, the polyterpenol based OFET device showed significant improvements. The addition of the polyterpenol interlayer in the OFET shifted the threshold voltage significantly; + 20 V to −3 V. The presence of trapped charge was not observed in the polyterpenol interlayer. This assisted in the improvement of effective mobility from 0.012 to 0.021 cm²/Vs. The switching property of the polyterpenol based OFET was also improved; 10⁷ compared to 10⁴. The results showed that the non-synthetic polyterpenol polymer film is a promising candidate of insulators in electronic devices.