Films of tetrachlorosubstituted cobalt phthalocyanines: the effect of the position of substituents and the deposition method on their structure and sensor properties
摘要
In this work, we investigate the effect of deposition techniques, such as physical vapor deposition (PVD) and spin coating (SC), on the structure and chemiresistive sensor response of the films of chlorinated cobalt phthalocyanines bearing substituents in peripheral (CoPcCl4-p) and non-peripheral (CoPcCl4-np) positions of the macroring to low concentrations of ammonia and hydrogen sulfide. The crystal structure (C2/c space group, Z’ = 0.5) of CoPcCl4-np has been determined for the first time. PVD films of both CoPcCl4-p and CoPcCl4-np demonstrated a clear preference for a specific orientation in relation to the surface of the substrate. The SC CoPcCl4-p film had a high degree of crystallinity, but it did not have a preferred orientation. In contrast, the SC CoPcCl4-np film was amorphous. When studying the chemiresistive sensor response to ammonia and hydrogen sulfide, it was found that CoPcCl4-p behaved like an n-type semiconductor and CoPcCl4-np behaved like a p-type semiconductor, which was explained using quantum chemical calculations. The sensor response of both films produced by the PVD method was higher than that of the films obtained by spin coating. At the same time, the response of CoPcCl4-p films to NH3 and H2S was over three times greater than that of CoPcCl4-np films.