A new competitive technique for the production of porphyrin thin films: the Glow Discharge induced Sublimation (GDS)

Thin porphyrin assemblies, widely used as sensing materials in different kinds of transducers, are usually produced through chemical deposition techniques. In this work a new physical technique named Glow-Discharge-induced Sublimation (GDS) has been employed for the first time for the production of cobalt 5,10,15,20 meso-tetraphenyl porphyrin (CoTPP) thin films. For the sake of comparison, CoTPP coatings have been also produced by vacuum evaporation and spin coating procedures. The inspection of the surface morphology with a Scanning Electron Microscope evidenced a higher surface roughness of GDS samples with respect to films deposited by means of conventionally used procedures. Optical measurements performed in atmospheres containing ethyl alcohol vapours highlight that GDS films yield more than ten times intense responses in comparison with the films deposited through the commonly used techniques, very fast response times (t50 = 12 sec and t90 = 72 sec) and fast and complete recovery.