Room temperature detection of H2S by flexible gold–cobalt phthalocyanine heterojunction thin films

Abstract We report an improved H 2 S response of flexible gold (Au)–cobalt phthalocyanine (CoPc) heterojunction thin films at room temperature. The Au–CoPc films exhibit very high charge carrier density at the surface due to (i) the difference in work function of Au and CoPc and (ii) enhanced adsorbed oxygen on the CoPc surface owing to spillover effect. Both of these effects make the Au–CoPc films more oxidative to the H 2 S in comparison to pure CoPc films. The response of the films on exposure to H 2 S is attributed to the shrinkage of the hole accumulation layer of CoPc due to electron transfer from adsorbed electron donor H 2 S. The gas sensing characteristics of the films were found to be stable for the bending radius >20 mm.