Fluorophobic Effect Enables Selective Detection of PFAS in Water with Electrolyte‐Gated Organic Transistors

PerFluoroAlkyl Substances (PFAS) are responsible of major environmental pollution worldwide, as they are both persistent and mobile. Environmental agencies impose strict regulations about PFAS in drinking water, hence, there is an urgent need for on-field deployable, rapid, reproducible, and distributed monitoring of PFAS. This work demonstrates an ultra-sensitive sensor for perfluoroalkyl acids based on an organic transistor whose gate is functionalized with a binary self-assembled monolayer containing a perfluorinated molecule. The device exploits the fluorophobic effect for selectively recognizing different PFAS based on the different number of fluorous interactions, viz. fluorine-fluorine (F···F) contacts, that can be formed. Remarkably, the organic transistor senses differences in the binding energy to linear PFAS surfactants in water of 4 ± 1 kJ mol−1, which corresponds to one ─CF2- unit. This device allows to quantify PFAS in water down to ppt level of detection.