Enhancement of NO2 gas detection in hybrid silver nanoparticles-phthalocyanine thin films

Phthalocyanine-functionalized plasmonic sensing systems are typically based on Kretschmann configuration. Such scheme of detection utilizes spectral or angular modulation of reflected light, which is induced by surface plasmon's excitation in the metal film on prism. Phthalocyanine's layer plays a role of analyte adsorber. In present paper we offer another approach to phthalocyanine-plasmonic sensing, where both local surface plasmon resonance and optical absorption of phthalocyanines are simultaneously detected. Hybrid Ag nanoparticles (AgNps) - low symmetrical A3B zinc phthalocyanine (ZnPc) thin films were prepared, and their NO2 gas sensitive properties were examined. Since the plasmon resonance of AgNps was properly tuned to charge-transfer band of ZnPc-NO2 complex, we found out more than two-fold increase of the optical response to NO2 exposure in AgNps-ZnPc thin films compared to ZnPc films without AgNps.