Molecular Engineering of Porphyrin‐Tapes/Phthalocyanine Heterojunctions for a Highly Sensitive Ammonia Sensor

International audienceModulating the interfacial charge alignments by molecular engineering in an organic heterojunction device is a smart strategy to improve its conductivity, which can be exploited in high performance gas sensors development. Herein, the fabrication of new organic heterojunction devices based on porphyrin tapes and phthalocyanines and their potentiality in ammonia sensing at different relative humidity (rh) are investigated. The devices are built using dry approach relying on oxidative chemical vapor deposition for simultaneous synthesis, doping and deposition of the porphyrin tape layer and physical vapor deposition of phthalocyanine layer. The association of the porphyrin tapes with copper phthalocyanine (CuPc) or its perfluorinated analogue (Cu(F16Pc)) in a bilayer device configuration revealed a non-linear current-voltage characteristics, assigned to the formation of organic heterojunction at the bilayer interface. Cu(F16Pc)-based devices revealed higher response, faster sorption kinetics, stable baseline and less interference from rh fluctuations towards ammonia than CuPcbased devices which are attributed to more conducting interface in the former. Moreover, depending on the porphyrin tape associated, Cu(F16Pc)-based devices exhibited sensitivit