p-Type and n-type conductometric behaviors of octachloro-metallophthalocyanine-based heterojunctions, the key role of the metal

In the present work, we determined the electrical properties of octachlorinated metallophthalocyanines with Co(II) and Cu(II) ions as metal centers. We engaged them in heterojunctions, with lutetium bisphthalocyanine as a partner. Surprisingly, cobalt and copper complexes show opposite behaviors, the first being an n-type material whereas the latter is a p-type material, as deduced from the response of the heterojunctions towards ammonia; showing the unusual key role played by the metal center. While the LuPc2/Cu(Cl8Pc) complex exhibits a negative response to ammonia, the LuPc2/Co(Cl8Pc) complex exhibits a positive response to ammonia, with a sensitivity of 1.47%.ppm(-1) at concentrations lower than 10 ppm and a limit of detection of 250 ppb. All the devices operate at room temperature and in real atmosphere.