Fabrication and characterization studies in organic semiconductor thin films of H2PcOC8 ZnPcOC8 and CuPcOC8

Abstract

The present investigation comprises of the studies on the electrical, optical and structural characterisations of H2PcOC8, ZnPcOC8 and CuPcOC8 thin films. The effects of gamma irradiation on the optical and electrical properties are also studied. Powdered samples of spectroscopically pure H2PcOC8, ZnPcOC8 and CuPcOC8 obtained from Sigma Aldrich Chemical Company, USA are used as the source material. Thin films are prepared at a base pressure of 10-6 m. bar using Hind Hivac 12 A4 thermal evaporation plant. Thicknesses of the films are measured using Tolansky s multiple beam interference technique. The films are annealed in air and vacuum for one hour. Electrical studies are performed using a programmable Keithley electrometer (model No. 617). The effects of air and vacuum annealed samples on the electrical conductivity are also studied. Activation energies are determined. Optical characterisations of the thin films are carried out with different thicknesses and for different air and vacuum annealing temperatures. Absorption spectra of these thin films are recorded using Shimadzu 160 A spectrophotometer. Band gaps are determined in each case. Structure of the thin films is studied by X-ray diffractograms (XRD). Surface morphological characterisations of these thin films are done using JEOL JSM 6390 Scanning Electron Microscope (SEM). The effects of gamma irradiations on the optical and electrical properties are also studied by irradiating the thin films with gamma rays using Gamma ray Chamber 5000 newline