Solution processed photopatternable high-k nanocomposite gate dielectric for low voltage organic field effect transistors

Abstract

We report an organic field effect transistors (OFETs) with photo-patternable, solution processed nanoparticle composite high-k gate dielectric layer. The dielectric layer consists of Barium Titanate (BT) nanoparticles dispersed in SU-8, which makes it possible to use solution-processable methods to prepare the dielectric layer. The dielectric constant k of the nanoparticle composite films can be tuned over a wide range by varying the concentration of BT particles, which enables lower voltage operation possible with these composite gate dielectric films. OFETs with P3HT as the semiconducting layer have been demonstrated; it was found that the OFETs with the nanocomposite dielectric layer show a significant improvement in the drive current yet retaining the photopatternability, which is an advantage for circuit fabrication. The composite being a high-k enables low voltage operation (∼4 V) compared to pristine SU-8 as a gate dielectric operating at high voltages (∼40 V). Working organic transistors and inverters with a high-k nanocomposite dielectric layer (k > 13) with considerably lower leakage current have been demonstrated. This method allows low cost preparation of OFETs without the complicated gate dielectric deposition methods.