Radio frequency plasma polymerized thin film based on eucalyptus oil as low dielectric permittivity, visible and near-infrared (NIR) photoluminescent material

Thin films derived from eucalyptus oil was fabricated on glass and silicon substrate by rf plasma polymerization technique and characterized by FTIR, FESEM, AFM, Ellipsometry, UV–Visible and Photoluminescence spectroscopy. The dielectric constant and dielectric loss of the thin films were estimated using spectroscopic ellipsometry technique. Functional groups related to chromophores present in the eucalyptus oil thin films were identified using FTIR spectroscopy. π − π^* interband transitions (306 nm) and intramolecular charge transfer (556 nm) was observed from the absorption spectra of the polymerized thin films. The indirect optical band gap estimated using Tauc plot was 3.66 eV, which revealed the semiconducting nature of the thin film. The value of real part of dielectric constant (ϵ′) was less than 2.44, which indicated a low dielectric permittivity behaviour of the film in the optical regime. The photoluminescence emission studies and CIE colour coordinates showed that plasma polymerized eucalyptus oil thin films exhibits yellow and IR emission.