Synthesis of Polypyrrole/MoO₃ Hybrid Thin Films and Their Volatile Organic Compound Gas-Sensing Properties

Abstract

Thin films of the intercalated organic−inorganic hybrids (PPy)xMoO3 (PPy: polypyrrole) have been prepared by an ex-situ intercalation process. The host MoO3 films were first deposited on LaAlO3 (LAO) single-crystal substrates by using a CVD method followed by the intercalation of PPy into the MoO3 films. The preparation of highly b-axis oriented MoO3 films is crucial to prepare the (PPy)xMoO3 films. The (PPy)xMoO3 thin film shows a semiconducting-like transport with an activation energy of 0.21 eV. The (PPy)xMoO3 thin films show a distinct response to VOCs by increasing their electrical resistivity and exhibit higher sensitivities to polar analytes such as formaldehyde and acetaldehyde, whereas it showed almost no response to toluene and benzene.