Flexible organic ion-gated transistors with low operating voltage and light-sensing application

Ion-gated transistors are attracting significant attention due to their low operating voltage (<1 V) and modulation of charge carrier density by ion-gating media. Here we report flexible organic ion-gated transistors based on the high mobility donor-acceptor conjugated copolymer poly[4-(4,4-dihexadecyl 4H-cyclopenta[1,2-b:5,4-b ']-dithiophen-2-yl)-alt[1,2,5]thiadiazolo[3,4c]pyridine](PCDTPT) and the ionic liquid [1-ethyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide] as the ion-gating medium. Electrical characteristics of devices made on both [rigid (SiO2/Si) and flexible (polyimide (PI))] substrates showed very similar values of hole mobility (similar to 1 cm(2) V-1 s(-1)) and ON-OFF ratio (similar to 10(5)). Flexible ion-gated transistors showed good mechanical stability at different bending curvature radii and under repetitive bending cycles. The mobility of flexible ion-gated transistors remained almost unchanged upon bending. After 1000 bending cycles the mobility decreased by 20% of its initial value. Flexible photodetectors based on PCDTPT ion-gated transistors showed photosensitivity and photoresponsivity values of 0.4 and 93 AW(-1).

Automated summary

Ion-gated transistors based on organic materials, such as PCDTPT and an ionic liquid, show promising electrical characteristics on both rigid and flexible substrates. The flexible devices exhibit good mechanical stability and only a slight decrease in mobility after repetitive bending cycles. Flexible photodetectors based on these ion-gated transistors demonstrate high photosensitivity and photoresponsivity values.