A study of the structural features and sensor properties of zinc 2,9,16,23-tetra-tert-butylphthalocyanine films

A comparative study of the structural features of zinc 2,9,16,23-tetra-tert-butylphthalocyanine films (ZnPc(^tBu)₄) obtained by vacuum thermal deposition and spin coating techniques is performed. By powder X-ray diffraction, 2D GIXD, and optical absorption spectroscopy it is shown that ZnPc(^tBu)₄ films obtained by the spin coating technique consist of a disordered α-phase with small crystallites. After annealing at 200 °C for 3 h the films transform into the β-phase, with crystallite sizes increasing, however, they remain disordered relative to the substrate surface. On heating under the same conditions, the ZnPc(^tBu)₄ films obtained by thermal vacuum sublimation transform from the weakly oriented low-temperature α-phase into the oriented β-phase. Dependences of a chemiresistive sensor response of the ZnPc(^tBu)₄ films to ammonia (10-50 ppm) are investigated depending on the preparation and annealing methods of the films.