Electrical Performance of Protein-Based Flexible MIM Structure Fabricated at Room Temperature for Proteotronic Applications

The incorporation of Protein in electronic devices coined as “Proteotronics” has emerged as the breakthrough technology in the modern organic electronic industry. Papain, a plant-based protein has been used as dielectric material in Metal–Insulator–Metal structure fabricated on Indium doped Tin Oxide (ITO) coated flexible Polyethylene Terephthalate (PET) substrate with ITO as the top electrode. Thickness of the spin-coated protein film was measured using Field Emission Scanning Electron Microscope (FESEM), and the optical bandgap of the protein was estimated using Ultraviolet–Visible Spectroscopy (UV–Vis). Raman spectroscopy was used to reveal the secondary structure of Papain. Photoluminescence showed the absorption band as well as presence of defect state. Atomic Force Microscopy (AFM) was used to study the surface morphology of the film. Capacitance–voltage characteristics was performed that showed capacitance density 0.995 fF/µm2 at 200 kHz along with negative quadratic co-efficient of voltage. The number of dipoles and permanent dipole moment were found as 3.33 × 1017 cm−3 and 1.5 × 10–25 C-m respectively. The charge transport mechanism was described using ionic double layer model.