Improving the mobility of D-A polymer PTB7-Th thin film field-effect transistors through organic salt doping

Organic salt doping is an effective method to control the electrical properties of organic semiconductor materials, while its underlying mechanism remains to be studied. In this work, we report the improvement of organic fieldeffect transistor (OFET) performance by doping the D-A polymer semiconductor PTB7-Th with organic salts. The underlying mechanism of PTB7-Th's organic salt doping in OFETs has been explored to fill the existing research gap. The doping of organic salts can improve the hole mobility of the device and change the threshold voltage. In addition, at low doping ratios, the on-off ratio of the device is not sacrificed but remains unchanged. Finally, we have made a series of characterizations of the properties of doped polymers through absorption, EPR, and UPS, which provide specific guidelines for modifying D-A polymer devices.