Characterization of drop-cast copper phthalocyanine thin films for ammonia sensing

A cost-effective drop-cast technique has been used to deposit copper phthalocyanine (CuPc) films on a glass substrate. The obtained films have undergone structural, optical and electrical characterization after annealing at different temperatures – that is, 100, 150 and 200°C. The X-ray diffraction spectra confirm the formation of CuPc films. The absorption spectra of the drop-cast CuPc films show two dominant bands – Q-band and Soret band – within wavelengths of 300–800 nm, respectively. Phase transformations from the α-phase to β-phase have been observed from structural and optical characterization. The current–voltage parameters of the films show ohmic contact, and their activation energies lie in the range of 0·21–0·54 eV annealed within temperatures of 100–200°C. The vapor-sensing characteristics of the CuPc-based sensor toward ammonia at different concentrations (15–230 parts per million) have been evaluated. These measurements reveal that CuPc films are a good candidate as ammonia sensors.