Electrical and optical properties of thermally-evaporated thin films from A2[TiO(C2O4)2] (A = K, PPh4) and 1,8-dihydroxyanthraquinone

Abstract

In this work, the synthesis of molecular materials formed from A2[TiO(C2O4)2] (A=K, PPh4) and 1,8 dihydroxyanthraquinone is reported. The synthesized materials were characterized by atomic force microscopy (AFM), infrared (IR) and ultraviolet-visible (UV–vis) spectroscopy. IR spectroscopy showed that the molecular-material thin-films, deposited by vacuum thermal evaporation, exhibit the same intra-molecular vibration modes as the starting powders, which suggests that the thermal evaporation process does not alter the initial chemical structures. Electrical transport properties were studied by dc conductivity measurements. The electrical activation energies of the complexes, which were in the range of 0.003–1.16eV, were calculated from Arrhenius plots. Optical absorption studies in the wavelength range of 190–1090nm at room temperature showed that the optical band gaps of the thin films were around 1.9–2.3eV for direct transitions Egd. The cubic NLO effects were substantially enhanced for materials synthesized from K2[TiO(C2O4)2], where χ(3) (−3ω; ω, ω, ω) values in the promising range of 10−12esu have been evaluated.