Ultrasensitive ppb-Level Detection of Trifluoroacetic Acid Vapor Using Buckybowl-Based Organic Field-Effect Transistors † †

Abstract

Organic field-effect transistor (OFET) chemical sensors have attracted considerable interest for their high sensitivity and compatibility with diverse substrates. Here, we present an OFET sensor for trifluoroacetic acid (TFA) vapor detection, employing a buckybowl derivative, 3S-4F, as the active semiconducting layer. The 3S-4F molecule combines a bowl-shaped trithiasumanene (TTS) core with a perfluorobenzopyrazine (pFBPz) unit. Strong concave-convex π-π interactions between TTS moieties drive columnar stacking in single crystals, enabling efficient charge transport. Simultaneously, the pFBPz unit confers basicity, allowing selective binding with TFA. Benefiting from this dual design, 3S-4F single-crystal OFET sensors deliver exceptional performance, including a responsivity of 517.3% at 600 ppb TFA, ultrafast response/recovery times (2.09/2.35 s), a low detection limit (216.5 ppb), and excellent selectivity over other organic vapors. This study demonstrates a molecular design approach for developing highperformance OFET chemical sensors.