Optical characteriziation of zinc phthalocyanine langmuir-blodgett films for gas sensing application

We report the use of zinc phthalocyanine (ZnPc) thin films as an optical gas sensor. The ZnPc thin films were fabricated by Langmuir-Blodgett technique onto quartz substrates. The responses of the thin films to various volatile organic compounds (VOCs) were recorded by using optical absorption spectroscopy under static conditions. It was found that the thin films presented a reversible changes in the absorption spectra after exposure to the test gas. The strongest gas-sensing response was observed when the films were exposed to pyridine. The experimental results indicate that the phthalocyanine can easily react with the VOCs which include electron donating group or electron withdrawing group. And the responses are in good agreement with the intensity of electron donating or electron withdrawing ability.