Fluorimetric Detection\nof Vapor Pollutants with Diketopyrrolopyrrole\nPolymer Microcavities

The increasing prevalence and detrimental effects of\nvolatile organic\ncompounds are driving the need for selective on-site sensors that\ndo not require complex sampling or instrumentation. Broadband selective\nsensors exhibiting selectivity based on their distinct response mechanism\nis becoming of increasing technological relevance in both industrial\nand urban settings. In this context, we propose a label-free sensor\nbased on a polymeric planar microcavity embedded with a fluorescent\norganic dye, designed to detect various pollutants in the vapor phase.\nThe sensor consists of alternating layers of cellulose acetate and\npoly(<i>N</i>-vinylcarbazole) and contains a polystyrene\ndefect layer doped with a quadrupolar diketopyrrolopyrrole. Both the\nstructural properties of the polymer microcavity and the dye in the\ndefect layer contribute to the sensor’s response to analytes,\ncreating a dual-probe system where a single photonic element translates\nchemical signals into optical signals, namely, transmission and fluorescence\nspectral variations. The discrimination capability of the photonic\nstructure arises from the physicochemical interactions between the\nanalytes and the polymer components. To validate our approach, we\nevaluate the sensor’s response to four distinct volatile molecules\nand investigate the mechanisms influencing the optical response.