VOCs adsorption induced surface potential changes on phthalocyanines: A combined experimental and theoretical approach towards food freshness monitoring

• VOCs’ interaction with metal-free (H 2 Pc) and iron (FePc) phthalocyanines is studied. • SKP studies reveal that FePc shows highly selective response to nonanal in dark. • Interestingly, FePc shows higher response to 1-hexanol under visible light exposure. • It can be used to monitor 1-hexanol, a marker for food freshness monitoring. Many organic molecules such as porphyrins, pthalocyanines, pyrene ligands and so on are being used to detect volatile organic compounds (VOCs). The richness in π-electrons, coordination metals and their structural integrity make them as potential candidates for chemical sensing applications. In this work, metal free (H 2 Pc) and iron (II) phthalocyanines (FePc) are used for detecting VOCs such as 1-hexanol, nonanal, triethylamine and so on. The structural, morphological and optical properties of as deposited films of H 2 Pc and FePc on fluorine doped tin oxide substrates are characterized by XRD, HR-SEM, UV–Vis adsorption and Raman spectroscopy studies. Their gas adsorption properties are investigated through scanning Kelvin probe by means of change in contact potential difference in dark as well as light illumination conditions. Among both pthalocyanines, FePc shows highly selective response towards 1-hexanol under visible light exposure. Interestingly, the one to one molecular computations have revealed that FePc show higher interaction towards VOCs when compared to H 2 Pc. Overall, being a marker for food freshness monitoring, 1-hexanol can be detected using FePc based photo enhanced room temperature gas sensors.