Nonvolatile electrical switching behavior observed in a functional polyimide thin film embedded with silver nanoparticles

Abstract

In this paper, we report our works on the synthesis of a silver-nanoparticle-embedded polyimide (PI) thin film and its electrical bistability. A soluble PI, (4,4′-(hexafluoroisopropylidene) diphthalic anhydride/4,4′-oxydianiline (6FDA/ODA), where the 6FDA part serves as an effective electron-accepting moiety, was synthesized in our current work as the polymer matrix. Silver nanoparticles (Ag NPs) with diameters less than 7 nm were subsequently generated in situ in the parent PI film via ultraviolet (UV) reduction of the (1,1,1-trifluoro-2,4-pentadionato) silver(I) complex (AgTFA) previously incorporated in the matrix. Electrical characterization results on the sandwiched device (ITO|PI (6FDA/ODA)/silver nanohybrid film|Au) indicate that the nanohybrid material possesses electrical bistability and the device exhibits two accessible conductivity states, which can be reversibly switched from the low-conductivity state to the high-conductivity state with an ON/OFF current ratio of about 10². The device with the PI (6FDA/ODA)/silver nanohybrid film as the active layer shows nonvolatile memory behavior. The high-conductivity state and the low-conductivity state of the device can be sustained after the removal of the applied voltage. Mechanisms regarding the charge transfer in the nanohybrid material were discussed.