Zinc(II)phthalocyanine as an optical window for visible region

Zinc(II)phthalocyanine with four naphthoxy pendant groups on the periphery was prepared by cyclotetramerization of 4-(2-naphthoxy)phthalonitrile. Thin films of this material have been prepared from solutions of different concentrations (5-100 mg ZnPc in 1 mL THF) by spin coating technique. Optical transmittance of thin films was measured using a spectrophotometer in the wavelength range of 260-1100 nm. Results show that transmittance is decreased with the increasing concentration in the ranges corresponding to B and Q absorptions, but the films can still be proposed as optical windows between these regions (~ 400-600 nm) due to very low absorbances. The surface morphology of the thin films was investigated by atomic force microscopy, AFM, and showed that all of the films have nano volcanic holes, except the film prepared from the most concentrated solution (100 mg ZnPc in 1 mL THF).