(521g) Design of Nanostructured Polymer-Based Ordered Ferroelectric Diode Memory Elements
Memory elements that are compatible with flexible, mechanically-robust substrates will be crucial for the design of future organic electronic applications. While many different materials and devices exist for these applications, one of the most promising architectures is that of the polymer-based ferroelectric diode (FeD). In these systems a blend composed of a ferroelectric polymer and a conjugated semiconducting polymer are deposited as a thin film between two electrodes. While the nanoscale structure and phase behavior associated with the interpenetrating networks of the ferroelectric and conjugated polymers has been shown to be of utmost import with respect to final device operation and performance, few studies were performed with systematic tuning of these domains sizes. Here, we demonstrate the creation of an ordered ferroelectric diode (OFeD) using a combination of electron-beam (e-beam) lithography and solution-printing techniques. Importantly, the nanofabrication strategy does not alter the crystal structure of the ferroelectric polymer domains and does not negatively impact the charge transport ability of the conjguated polymer domains. Through the systematic design and fabrication of nanostructured active layers, we demonstrate that there is an optimal domain spacing (~400 nm) for the OFeD active layers that balances the ability for ferroelectric domains to impart a remembered (i.e., written) charge state into the conjugated polymer domains and the necessity for the conjugated polymer to transport charge out of the device (i.e., read-out the device). Moreover, we demonstrate that, due to the solution-processable nature of the ferroelectric-conjugated polymer blend, that the OFeD fabrication paradigm can be readily shifted to a more scalable platform (i.e., beyond e-beam lithography) and is compatible with common flexible substrates. In this way, we establish both the fundamental physics that dictates OFeD operation and present a ready means by which to scale these devices for next-generation organic electronic applications.