Interfacial effects on resistive switching of vacuum spray deposited polymer thin films embedded with TiO2 nanoparticles under bending strain

The resistive switching of polymer films embedded with nanoparticles (NPs) offers the promise for future flexible and transparent memory applications. However, the polymer/NP interfacial effect on switching behavior under various mechanical stimuli is a vital issue that has received scant attention. Here, polymer thin films embedded with TiO2 NPs were fabricated by vacuum spray method to study how the polymer/NP interface affects the switching behavior, especially under severe bending conditions. Compared with that of the initial sample, the ON/OFF ratio decreases by two orders of magnitude with the conduction mechanism translating from trap-controlled space charge limited current conduction to Poole-Frankel emission after repetitive bending. Surface wrinkle and interfacial micro cracks were observed. Using the finite element analyses and quantum chemical calculation, we show that the TiO2 NPs produce strain-sensitive regions within the film, and micro cracks initiate and propagate along the polymer/NP interface under severe bending. Such cracks can serve as vacuum gap to block the carriers transport and further result in the deterioration of switching performance.