Observation of negative differential resistance in diketopyrrolopyrrole-based copolymer films

Remarkable and repeatable negative differential resistance (NDR) phenomenon was observed in a metal-polymer-metal structure diode based on bishexyloxy-divinyl-benzene-alt-diketopyrrolopyrrole (C6DPPPPV), a type of donor-acceptor (D-A) conjugated copolymer. Thickness dependence of the devices implied that the observed NDR characteristics were bulk-controlled. The device performance was considered to depend on the slow trapping and releasing processes related to the local deep states, which was enhanced by the growth and thermal rupture of conducting filaments through the organic layer. The results suggest that the D-A conjugated copolymer is a promising memory material based on NDR effect.