Electrophilic-Attack\nDoped Organic Field-Effect Transistors\nfor Ultrasensitive and Selective Hydrogen Sulfide Detection

Doping of organic semiconductors (OSCs) has been developed\nas an\neffective means of modulating the density and transfer efficiency\nof charge carriers; however, realization of effective doping to tailor\nthe chemical sensing performance of OSC-based sensors still remains\nnot explored extensively. In addition, the application of OSCs in\nchemical sensors is usually limited by the poor stability and low\nselectivity. Herein, flexible donor–acceptor copolymer-based\norganic field-effect transistor (OFET) chemical sensors are designed\nvia an electrophilic attack doping strategy. The p-dopant trityl tetrakis(pentafluorophenyl)\nborate (TrTPFB) can be effectively doped into the host molecular <i>N</i>-alkyl-diketopyrrolo-pyrroledithienylthieno[3,2-<i>b</i>]thiophene (DPPDTT). It is simple to alter the doping efficiency\nand film thickness (<i>ca</i>. 5.5–17.7 nm) by adjusting\nthe proportion and concentration of guest–host molecules, which\nendows facile carrier mobility and enhanced sensing sensitivity modulation\ntoward reducing gases at room temperature. Particularly, 1.0 mol%\nTrTPFB-doped DPPDTT achieved the highest response to H<sub>2</sub>S gas, including ultralow detection concentration (0.5 ppb), excellent\nselectivity, high humidity stability, and long-term storage stability.\nThis work can provide a new strategy for the potential applications\nof the organic electronic sensing devices.