Polymer/TiO2 Nanoparticles interfacial effects on resistive switching under mechanical strain

Flexible resistive random access memory devices based on polymer thin films embedded with nanoparticles (NPs) offer the promise for the next generation nonvolatile memory applications. We systematically investigated the influence of polymer/NPs interface on switching behavior of TiO2 NPs embedded in matrixes of polymethyl methacrylate, poly (9,9-di-octylfluorene-alt-benzothiadiazole) (PFBT), poly (N-vinylcarbazole) or poly (3-hexylthiophene-2,5-diyl) under mechanical bending conditions fabricated by vacuum spray deposition. The bipolar switching was observed with ON/OFF ratio more than 10(3) , in which samples with PFBT matrix exhibit the best bending endurance. Using quantum chemical calculations and electric field simulation, we showed the switching mechanism can be ascribed to the field-induced tunneling between adjacent NPs. Moreover, different from other matrixes, the segments of the PFBT molecules may serve as charge traps or blocks. The finite element studies and numerical simulation revealed that the NPs may serve as stress singularity, and interfacial microcracks may initiate and propagate along polymer/NPs interfaces after repeated bending. Such underlying damage can serve as blocks to hinder the charge transport and further deteriorates the switching performance. Our work may provide useful information on mechanical reliability of polymer/NPs interfaces for the development of flexible electronics.