Ferroelectricity, a bistable ordering of electrical dipoles in a material, is widely used in sensors, actuators, nonlinear optics, and data storage. Traditional ferroelectrics are ceramic based. Ferroelectric polymers are inexpensive lead-free materials that offer unique features such as the freedom of design enabled by chemistry, the facile solution-based low-temperature processing, and mechanical flexibility. Among engineering polymers, odd nylons are ferroelectric. Since the discovery of ferroelectricity in polymers, nearly half a century ago, a solution-processed ferroelectric nylon thin film has not been demonstrated because of the strong tendency of nylon chains to form hydrogen bonds. We show the solution processing of transparent ferroelectric thin film capacitors of odd nylons. The demonstration of ferroelectricity, as well as the way to obtain thin films, makes odd nylons attractive for applications in flexible devices, soft robotics, biomedical devices, and electronic textiles.

Ferroelectric tunnel junctions (FTJs) are ideal resistance‐switching devices due to their deterministic behavior and operation at low voltages. However, FTJs have remained mostly as a scientific curiosity due to three critical issues: lack of rectification in their current‐voltage characteristic, small tunneling electroresistance (TER) effect, and absence of a straightforward lithography‐based device fabrication method that would allow for their mass production. Co‐planar FTJs that are fabricated using wafer‐scale adhesion lithography technique are demonstrated, and a bi‐stable rectifying behavior with colossal TER approaching 106% at room temperature is exhibited. The FTJs are based on poly(vinylidenefluoride‐co‐trifluoroethylene) [P(VDF‐TrFE)], and employ asymmetric co‐planar metallic electrodes separated by <20 nm. The tunneling nature of the charge transport is corroborated using Simmons direct tunneling model. The present work is the first demonstration of functional FTJs manufactured via a scalable lithography‐based nano‐patterning technique and could pave the way to new and exciting memory device concepts.

Polymeric nanocomposite thin films of magnetic nanoparticles blended with the ferroelectric polymer poly-(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) are promising candidates for multiferroic applications. To date, only thick-film multiferroic nanocomposites have been reported. Fabrication of nanocomposite thin films along with the study of the ferroic properties with magnetic nanoparticle loading is crucial for the realization of functional devices. However, systematic studies, and in particular the dynamic of ferroelectric polarization switching and a solid understanding of the microstructure formation in thin films, are still missing. Here, we present solution-processed P(VDF-TrFE):magnetic nanoparticle thin films for multiferroic applications, wherein the ferroic properties, polarization switching dynamic, and the microstructure formation are studied as a function of nanoparticle loading. Our results demonstrate that as the nanoparticle loading increases, the ferroelectric polarization of the nanocomposite decreases and the saturation magnetization increases. Moreover, the presence of the nanoparticles substantially increases the polarization switching time and shifts the switching mechanism to one-dimensional growth. The P(VDF-TrFE):magnetic nanoparticle solution phase separates upon film casting. The crystalline regions of P(VDF-TrFE) are pure. The amorphous regions accommodate the nanoparticles. The phase separation leads to agglomerated nanoparticles at higher loadings, and eventually stratified vertical phases occur. The insight gained from the study of thin-film microstructure would help to optimize the performance of the nanocomposite for multiferroic applications and can be used for better understanding of the polymer:nanoparticle nanocomposites for energy storage and memory applications.

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Ferroelectricity has been proposed as one of the potential origins of the observed hysteresis in photocurrent-voltage characteristics of perovskite based solar cells. Measurement of ferroelectric properties on perovskite solar cells is hindered by the presence of (in)organic charge transport layers. Here we fabricate metal-perovskite-metal capacitors and unambiguously show that methylammonium lead iodide is not ferroelectric at room temperature. We propose that the hysteresis originates from the movement of positive ions rather than ferroelectric switching.

Organic bistable diodes based on phase-separated blends of ferroelectric and semiconducting polymers have emerged as promising candidates for non-volatile information storage for low-cost solution processable electronics. One of the bottlenecks impeding upscaling is stability and reliable operation of the array in air. Here, we present a memory array fabricated with an air-stable amine-based semiconducting polymer. Memory diode fabrication and full electrical characterizations were carried out in atmospheric conditions (23 °C and 45% relative humidity). The memory diodes showed on/off ratios greater than 100 and further exhibited robust and stable performance upon continuous write-read-erase-read cycles. Moreover, we demonstrate a 4-bit memory array that is free from cross-talk with a shelf-life of several months. Demonstration of the stability and reliable air operation further strengthens the feasibility of the resistance switching in ferroelectric memory diodes for low-cost applications.

Solution-processed memory diodes based on phase separated blends of ferroelectric and semiconducting polymers in the low resistance on-state operate similar to a vertical field-effect transistor at the pinch-off. Numerical simulations have shown that the performance of the diode is dominated by the conduction of charge carriers at the interface between the semiconductor and ferroelectric phases. Here, we present an unambiguous experimental demonstration of the charge injection process in the diodes. We employ a modified diode structure, wherein the electrode in contact with the semiconductor phase has been intentionally removed. Even in the absence of an electrical contact with the semiconductor phase, the diode still shows resistance switching. We provide numerical simulations that reproduce the experimentally measured I-V characteristics and therefore confirm interfacial conduction in the diodes. Furthermore, we discuss the implications of the proposed memory structure particularly in the performance of light-emitting diodes with built-in memory functionality, i.e., MEMOLEDs.

Reduced graphene oxide(rGO) has a lot of potential in the area of corrosion control of metals, because of its excellent barrier properties, dispersion capabilities, and impermeability. The current work hires on the corrosion resistance action of reduced graphene oxide(rGO) as an inhibitor for mild steel in simulated concrete pore solution. Here, three different nano rGO contained epoxy coatings were prepared by varying the percentage of rGO. The anticorrosion behaviour of rGO integrated epoxy composite coating was evaluated using open circuit potential and polarization studies. The results indicated that rGO nanoparticles were properly distributed in the epoxy coating and showed excellent barrier properties. Moreover, anti-corrosion processes for composite coatings improved by the addition of various percentages of rGO were apparently hypothesized, implying that epoxy coating containing 1.0 wt.% rGO showed better corrosion resistant behaviour in concrete pore solution medium containing 0.5M NaCl solution.