Selectivity enhancement for toluene vapor by applying a cavitand layer in organic field-effect transistor sensors

Organic semiconductor films are granular and contain a lot of grain boundaries. Due to these structural characteristics, organic field-effect transistors (OFET's) are sensitive to organic vapor analytes. Of commonly adopted organic semiconductors, CuPc (copper phthalocyanine) devices show suitable characteristics for organic sensing. A layer of solution-cast cavitand designated 4T5QX is thought to enhance the selectivity for aromatic vapors when it is applied to organic semiconductor surface as a receptor. Toluene vapor was used as the aromatic analyte to measure the sensitivity enhancement of cavitand-covered CuPc devices. A cavitand solution of concentration 4.5x10⁻³ mol/L was drop-cast over the CuPc devices. All devices exhibited higher response rate when they were covered with a layer of cavitand 4T5QX