High ON/OFF ratio single crystal transistors based on ultrathin thienoacene microplates

The high ON/OFF ratios of organic single crystal field-effect transistors (FETs) are obtained based on dinaphtho[3,4-d:3',4'-d']benzo[1,2-b:4,5-b']dithiophene (Ph5T2) ultrathin microplates. The ON/OFF ratio is over 108 with a small sweep range of gate voltage (<45 V) in air at room temperature when the dielectric is modified with octadecyltrichlorosilane (OTS). The high ON/OFF ratio is related to the decreased off-state current by molecular design and the increased on-state current by dielectric modification. The ON/OFF ratio up to 1.3 x 10(7) can also be realized on a flexible transparent substrate. The ultrathin Ph5T2 single crystal provides stable performance even though the flexible device experiences a bending/recovering test for 200 times. The high ON/OFF ratio combined with the high mobility up to 0.51 cm(2) V-1 s(-1) and the good flexibility of the ultrathin organic single crystals show their promising potential in electronic applications.