Optical and electrical properties of nanostructured heterojunction (Au|PdPc|ClAlPc|Al) and using as O2 sensor

Nanostructure thin films and sandwich devices of palladium phthalocyanine (PdPc) and chloroaluminum-phthalocyanine (ClAlPc) were prepared by thermal evaporation technique. Optical and structural properties of nanostructure thin films were investigated by XRD, SEM and optical absorption. The SEM images demonstrated PdPc (40-60 nm) and ClAlPc (30-50 nm) nanostructures. XRD patterns showed that thin films are in a-phase at room temperature. Also, optical bandgap energy of thin films was calculated by optical absorption spectra. Heterojunction (Au|PdPc|ClAlPc|Al) and single layer (Au|PdPc|Al and Au|ClAlPc|Al) devices were fabricated. Electrical measurements demonstrated the semiconducting and photo-conducting behavior of thin films. After that, devices were exposed to different concentrations of O-2 at 300 K and 350 K and conductivity of thin films was increased on exposure to O-2. Heterojunction devices were more sensitive than other thin films and had better response and reversibility in comparison with single layer devices at 350 K. Finally, 10% O-2 was mixed with different percentages of relative humidity and all results showed that the conductivity of thin films is reduced on exposure to O-2 mixed to humidity.