Doped poly 3-methylthiophene device exhibits negative-differential resistance

Abstract

Poly 3-methylthiophene (P3MT) polymer is electrochemically deposited on stainless steel substrate and a sandwich device structure (SS/P3MT/Ag) is realized by placing a top metal contact to fabricate a two-terminal device. The polymer is first doped with PF 6 − & ClO 4 − dopants and then de-doped for 30 seconds. The current-voltage (I-V) measurement is carried out on a de-doped P3MT device to probe the charge-transport and negative-differential resistance (NDR). In the present experiment, NDR and Charge transport mechanism varies with the dopant. The magnitude of NDR, i.e., peak-valley current (PVCR) depends on the voltage swept and dopants. We propose the reason for anomaly NDR is dopant-induced trap-states.