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Paper transistors have the advantages of recyclability, high abundance, low cost, disposability, and biodegradability. In this paper, a nonvolatile transistor fabricated on a paper substrate without protective layers by using solution-based methods is presented, and promising performance is reported. The memory window of ferroelectric field-effect transistors is approximately 16 V when the gate voltage is swept from +20 V to -20 V. The on/off ratio is 3.45 × 102, even on the paper substrate. Electrical characteristics of the memory device are not degraded, as compared with those of transistors on rigid substrates fabricated simultaneously.

In the original publication of the article, there are some mistakes regarding the sequence of references. Some references are mislocated. Here is the new version of the full paper.

This supplement contains 222 (angel number) further papers on false or unconfirmed ferroelectric properties in single crystals, ceramics and polymers and only concerns bulk materials. Thus, the number of such papers has reached huge value 727. The papers marked in red have drastically broken the principles of symmetry because they reported the existence of ferroelectricity in crystals without the polar axis.

The nanocomposites consisting of graphene oxide (GO) and ferroelectric copolymer poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] have been successfully synthesized by a co-evaporation method. The structural, dielectric and ferroelectric properties of the composite papers are investigated. The Raman spectroscopy analyses on the nanocomposites GO/P(VDF-TrFE) reveal that the defects in GOs are reduced significantly by the loading of ferroelectric P(VDF-TrFE). The IG/ID ratio increases from 1.02 (for pure GO) to 1.17 [for GO/P(VDF-TrFE)-10%], revealing that the defects are reduced by the introduction of the nano-fillers due to a strong interaction between GO and P(VDF-TrFE) in the nanocomposites. The permittivity of the nanocomposites is enhanced by almost 3-times as compared to that of the pristine GOs. The nanocomposites show a notably raised polarization with high applied electric field. Furthermore, due to the high dielectric constants, the electrical energy storage density of the nanocomposites is as high as ~ 39.89 J cm−3 at 2.8 MV cm−1. The large energy density and high dielectric break down strength suggest that GO/P(VDF-TrFE) could be the promising novel materials for electrical energy storage.

Efficient separation of electron-hole pairs is vitally crucial to enhancing the analytical performance of paper-based photoelectrochemical (PEC) bioanalysis. Herein, a simple but effective strategy is developed to modulate the effective separation of photogenerated electrons and holes via introducing a polar charge carriers-created (PCC) electric field induced by a classical perovskite ferroelectric BaTiO3 (BTO). By inserting it between the n-type WO3 nanoflakes and p-type Cu2O (WO3 nanoflakes/BTO/Cu2O), the photoelectrode is endowed with a renewable PCC electric field, as a sustaining driving force, to guarantee the realization of directional separation of charge carrier (DSCC) strategy in PEC bioanalysis. The enduring PCC electric field can attract the electrons of Cu2O and holes of WO3, respectively, thereby regulating the directional migration of charge carriers and achieving an enhanced PEC photocurrent for the ultrasensitive quantification based on the highly efficient separation of electron-hole pairs. Consequently, with respect to WO3 nanoflakes/Cu2O and WO3 nanoflakes photoelectrode, the polarized WO3 nanoflakes/BTO/Cu2O photoelectrode exhibits 1.7 and 10.9 times higher photocurrent density, respectively. Benefiting from this, the prominent photocurrent density is obtained which is extremely beneficial for enhancing the sensitivity of PEC bioanalysis. Ultimately, the ultrasensitive detection of model prostate specific antigen (PSA) is realized and presents a linear range of 0.1 pg/mL-50 ng/mL with the detection limitation of 0.036 pg/mL. This work provides the basis for understanding the role of the polarized electric field induced by ferroelectric in tuning the charge separation as well as insights on strategies for constructing high-performance paper-based PEC bioanalysis.

As good alternatives for conventional rigid piezoelectric materials, piezoelectric nanocomposites combining piezoelectric materials and flexible polymer matrix demonstrate great potential for flexible nanogenerators. Rational design of the hybrid structure is important for performance optimization of piezoelectric nanocomposite. Here, we designed a hybrid piezoelectric paper through uniform assembly of vanadium doped ZnO (V-ZnO) mircoflowers in bacterial cellulose (BC) matrix by a in situ synthesis method. Different from pure ZnO where the c-axis of crystalline need to be oriented in order to get improved piezoelectric output, V-ZnO demonstrate ferroelectric property, which is prerequisite for poling with external high voltage in enhancing the output performance. The resultant hybrid paper demonstrated excellent flexibility and was used to fabricate flexible piezoelectric nanogenerators (PENGs). With excellent mechanical strength and durability, the V-ZnO/BC hybrid paper-based PENGs can work as self-powered motion sensors, which are capable of monitoring page-turning motions when integrated with pages of books. The V-ZnO/BC hybrid paper based PENGs are lightweight and inexpensive, which demonstrate promising applications for self-powered sensor networks and wearable electronics.

This study demonstrates a new and realizable possibility of 1T-type ferroelectric random access memory devices using an all solution processing method with cellulose paper substrates. A ferroelectric poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) thin film was formed on a paper substrate with an Al electrode for the bottom-gate structure, and then a semiconducting poly(3-hexylthiophene) (P3HT) thin film was formed on the P(VDF-TrFE)/paper structure using a spin-coating technique. The fabricated ferroelectric gate field-effect transistors (FeFETs) on the cellulose paper substrates demonstrated excellent ferroelectric property with a memory window width of 20 V for a bias voltage sweep from −30 to 30 V, and the on/off ratio of the device was approximately 102. These results agree well with those of the FeFETs fabricated on a rigid Si substrate. In order to compare and check the reproducibility of the characteristics of the FeFETs on the paper substrate, it also has been attempted to make FeFETs with various channel length and width ratios were fabricated. From the measured characteristic results, it can be seen that the electrical properties of FeFETs are almost similar regardless of the substrate type. These results will lead to the emergence of printable electron devices on paper. Furthermore, these nonvolatile paper memory devices, which are fabricated by a solution processing method, are reliable, very inexpensive; have a high density; and can be fabricated easily.

The photorefractive effect in photoconductive ferroelectric liquid crystals that contain photoconductive chiral compounds was investigated. Ter-thiophene compounds with chiral structures were chosen as the photoconductive chiral compounds, and they were mixed with an achiral smectic C liquid crystal. The mixtures exhibit the ferroelectric chiral smectic C phase. The photorefractivity of the mixtures was investigated by two-beam coupling experiments. It was found that the ferroelectric liquid crystals containing the photoconductive chiral compound exhibit a large gain coefficient of over 1200 cm-1 and a fast response time of 1 ms. Real-time dynamic amplification of an optical image signal of over 30 fps using the photorefractive ferroelectric liquid crystal was demonstrated.

This study demonstrates a new and realizable possibility of 1T-type ferroelectric random access memory devices using an all solution processing method with cellulose paper substrates. A ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) thin film was formed on a paper substrate with an Al electrode for the bottom gate structure, and then a semiconducting poly(3-hexylthiophene) (P3HT) thin film was formed on the P(VDF-TrFE)/paper structure using a spin-coating technique. The fabricated ferroelectric gate field effect transistors (FeFETs) on the cellulose paper substrates demonstrated excellent ferroelectric property with a memory window width of 20 V for a bias voltage sweep from −30 to 30 V, and the on/off ratio of the device was approximately 102. These results agree well with those of the FeFETs fabricated on a rigid Si substrate. These results will lead to the emergence of printable electron devices on paper. Furthermore, these non-volatile paper memory devices, which are fabricated by a solution processing method, are reliable, very inexpensive, have a high-density, and can be fabricated easily.

The authors of the title paper (J. Cryst. Growth 393 (2014) 7–12) report to have grown a novel organic nonlinear optical (NLO) crystal namely N,N-dimethylurea picrate (NNDMP) by the slow evaporation technique using dimethylformamide (DMF) as solvent. Many points of criticism, concerning the characterization of this so called NNDMP crystal, are highlighted in this comment to prove that NNDMP is not a novel NLO crystal.

Photoaligned ferroelectric liquid crystals are described. The new electrooptical modes as well as their new applications in displays and photonics are highlighted. Electrically suppressed helix (ESH) mode was considered as the most promising one.

In this paper, we describe the effect of the molecular structure of chiral anisotropic compounds and materials on their mesomorphic and physico chemical properties. Modifications of the molecules via cyclic and bridge fragments or via lateral substituents allowed the preparation and optimization of specific mixtures for different display applications. The formation of defect free layers in ferroelectric liquid crystals stable against various mechanical or temperature deformations was studied. A new electro-optic effect based on chiral-nematic mixtures for creating high-speed devices with switching time less than 1 ms was developed.

In this article, a polymer stabilized ferroelectric liquid crystal (FLC) is introduced. With the expose of UV light, the doped monomer formed a polymer network and thus stabilize the FLC working in electrically suppressed helix electric-optical mode. Therefore, we are able to achieve a high contrast ratio, fast response and low driving voltage display.

This paper describes the design and implementation of an electric field sample cell, used to perform in situ single-crystal synchrotron X-ray diffraction under an applied electric field and suitable for single-crystal samples that are greater than 100 µm in size., With the recent increase in research into ferroelectric, anti-ferroelectric and piezoelectric materials, studying the solid-state properties in situ under applied electric fields is vital in understanding the underlying processes. Where this behaviour is the result of atomic displacements, crystallographic insight has an important role. This work presents a sample environment designed to apply an electric field to single-crystal samples in situ on the small-molecule single-crystal diffraction beamline I19, Diamond Light Source (UK). The configuration and operation of the cell is described as well as its application to studies of a proton-transfer colour-change material.

Objectives. Since the end of the 20th century, liquid crystals have taken a leading position as a working material for the display industry. In particular, this is due to the advances in the control of surface orientation in thin layers of liquid crystals, which is necessary for setting the initial orientation of the layer structure in the absence of an electric field. The operation of most liquid crystal displays is based on electro-optical effects, arising from the changes in the initial orientation of the layers when the electric field is turned on, and the relaxation of the orientation structure under the action of surfaces after the electric field is turned off. In this regard, the high quality of surface orientation directly affects the technical characteristics of liquid crystal displays. The traditional technology of rubbing substrates, currently used in the display industry, has several disadvantages associated with the formation of a static charge on the substrates and surface contamination with microparticles. This review discusses an alternative photoalignment technology for liquid crystals on the surface, using materials sensitive to polarization of electromagnetic irradiation. Also, this review describes various applications of photosensitive azo dyes as photo-oriented materials. Results. The alternative photoalignment technology, which employs materials sensitive to electromagnetic polarization, allows to create the orientation of liquid crystals on the surface without mechanical impact and to control the surface anchoring force of a liquid crystal. This provides the benefits of using the photoalignment technology in the display industry and photonics—where the use of the rubbing technology is extremely difficult. The optical image rewriting mechanism is discussed, using electronic paper with photo-inert and photoaligned surfaces as an example. Further, different ways of using the photoalignment technology in liquid crystal photonics devices that control light beams are described. In particular, we consider switches, controllers and polarization rotators, optical attenuators, switchable diffraction gratings, polarization image analyzers, liquid crystal lenses, and ferroelectric liquid crystal displays with increased operation speed. Conclusions. The liquid crystal photoalignment and photopatterning technology is a promising tool for new display and photonics applications. It can be used for light polarization rotation; voltage controllable diffraction; fast switching of the liquid crystal refractive index; alignment of liquid crystals in super-thin photonic holes, curved and 3D surfaces; and many more applications.

Combined non-ambient X-ray and neutron diffraction have been used to observe lattice parameter convergence in polar phases of the xBi(Zn2/3 Nb1/3)O3–(1 − x)BaTiO3 system below the ferroelectric composition limit at x < 5.0%. The lattice parameter convergence is correlated with peaks in the dielectric and piezoelectric coefficients., The first determination of the phase diagram of the novel ferroelectric relaxor xBi(Zn2/3Nb1/3)O3–(1 − x)BaTiO3 (BZN-BT) has been achieved with a combination of high-resolution X-ray and neutron diffraction up to the miscibility limit near x(BZN) = 20.0% over a temperature range 20 < T < 400 K. The combined X-ray and neutron data show that the instability within the xBZN-(1−x)BT system reaches a maximum at x = 3.9% and is driven by B-site displacement and distortion of the oxygen octahedra in the polar phases. Composition-dependent effects include a narrow Amm2-dominated region focused at x = 3.9%, significant convergence of the lattice parameters in both P4mm and Amm2 phases, and sharp maxima in piezoelectric coefficient d 33 and maximum polarization P max. Lattice parameter dilation at x ≥ 4.0% was observed for both P4mm and Amm2 unit cells, alongside the first appearance of Pm 3 m at 295 K and the onset of significant dielectric relaxation. Low-temperature neutron diffraction indicated a weak or non-existent temperature dependence on the transition from ferroelectric at x = 3.9% to ferroelectric relaxor at x = 4.0%. Temperature-dependent phase transitions were eliminated near x = 3.0%, with the ferroelectric limit observed at x = 5.0% and a transition to a low-loss relaxor dielectric near x = 8.0%.

This article reports the first in situ diffraction result collected under applied electric field on a hybrid improper ferroelectric which shows a subtle yet robust preference for a switching mechanism that proceeds via an unwinding of the octahedral rotation mode., Improper ferroelectric mechanisms are increasingly under investigation for their potential to expand the current catalogue of functional materials whilst promoting couplings between ferroelectricity and other technologically desirable properties such as ferromagnetism. This work presents the results of an in situ synchrotron X-ray diffraction experiment performed on samples of Ca2.15Sr0.85Ti2O7 in an effort to elucidate the mechanism of hybrid improper ferroelectric switching in this compound. By simultaneously applying an electric field and recording diffraction patterns, shifts in the intensity of superstructure peaks consistent with one of the switching mechanisms proposed by Nowadnick & Fennie [Phys. Rev. B, (2016), 94, 104105] are observed. While the experiment only achieves a partial response, comparison with simulated data demonstrates a preference for a one-step switching mechanism involving an unwinding of the octahedral rotation mode in the initial stages of switching. These results represent some of the first reported experimental diffraction-based evidence for a switching mechanism in an improper ferroelectric.

A large enhancement (118%) of electric field-induced strain of KTa1−xNbxO3 is achieved by Mn doping. The intensified local heterogeneity and modified structural features yielded by Mn dopants are demonstrated to be responsible for improved piezoelectricity. The role of Mn doping in local structures and properties of KTa1−xNbxO3 crystals is revealed, providing a basis for material design and performance optimization., Ion doping, an effective way to modify the nature of materials, is beneficial for the improvement of material properties. Mn doping exhibits gain of piezoelectric properties in KTa1−xNbxO3 (KTN). However, the impact mechanism of Mn ions on properties remains unclear. Here, the effects of Mn doping on local heterogeneity and piezoelectric properties in KTN are studied. The electric field-induced strain of Mn-doped KTN is ∼0.25% at 10 kV cm−1, 118% higher than that of pristine KTN. Meanwhile, as a result of Mn doping, the dielectric permittivity was tripled and the ferroelectricity was modified. The changes in A1(2TO), B1 + E(3TO) and E(4TO) vibrations characterized by Raman spectra indicate increased local polarization, weak correlation of dipoles and distorted lattices in Mn-doped KTN, respectively. First-principles calculations demonstrate stronger local heterogeneity introduced by Mn dopants, which weakens the dipole correlations and reduces domain sizes. As a result, the decreased domain sizes, combined with the larger ratio of lattice parameters c and a of the Mn-contained portion, are responsible for the higher piezoelectricity. This work reveals the impact on properties of KTN from Mn dopants and the prominent role of local heterogeneity in improving piezoelectricity, being valuable for the optimization and design of material properties.

Piezoresponse force microscopy (PFM), as a powerful nanoscale characterization technique, has been extensively utilized to elucidate diverse underlying physics of ferroelectricity. However, intensive studies of conventional PFM have revealed a growing number of concerns and limitations which are largely challenging its validity and applications. In this study, an advanced PFM technique is reported, namely heterodyne megasonic piezoresponse force microscopy (HM‐PFM), which uses 106 to 108 Hz high‐frequency excitation and heterodyne method to measure the piezoelectric strain at nanoscale. It is found that HM‐PFM can unambiguously provide standard ferroelectric domain and hysteresis loop measurements, and an effective domain characterization with excitation frequency up to ≈110 MHz is demonstrated. Most importantly, owing to the high‐frequency and heterodyne scheme, the contributions from both electrostatic force and electrochemical strain can be significantly minimized in HM‐PFM. Furthermore, a special measurement of difference‐frequency piezoresponse frequency spectrum (DFPFS) is developed on HM‐PFM and a distinct DFPFS characteristic is observed on the materials with piezoelectricity. By performing DFPFS measurement, a truly existed but very weak electromechanical coupling in CH3NH3PbI3 perovskite is revealed. It is believed that HM‐PFM can be an excellent candidate for the ferroelectric or piezoelectric studies where conventional PFM results are highly controversial., A heterodyne megasonic piezoresponse force microscopy (HM‐PFM) is introduced for nanoscale ferro/piezoelectric characterization. HM‐PFM specially uses 106 to 108 Hz high‐frequency excitation and heterodyne method to measure piezoelectric strain, providing a substantial improvement for the signal source issue of conventional PFM. It is believed that HM‐PFM is an excellent candidate for ferro/piezoelectric studies where conventional PFM measurements are highly controversial.

A domain wall‐enabled memristor is created, in thin film lithium niobate capacitors, which shows up to twelve orders of magnitude variation in resistance. Such dramatic changes are caused by the injection of strongly inclined conducting ferroelectric domain walls, which provide conduits for current flow between electrodes. Varying the magnitude of the applied electric‐field pulse, used to induce switching, alters the extent to which polarization reversal occurs; this systematically changes the density of the injected conducting domain walls in the ferroelectric layer and hence the resistivity of the capacitor structure as a whole. Hundreds of distinct conductance states can be produced, with current maxima achieved around the coercive voltage, where domain wall density is greatest, and minima associated with the almost fully switched ferroelectric (few domain walls). Significantly, this “domain wall memristor” demonstrates a plasticity effect: when a succession of voltage pulses of constant magnitude is applied, the resistance changes. Resistance plasticity opens the way for the domain wall memristor to be considered for artificial synapse applications in neuromorphic circuits., By changing the density of conducting ferroelectric domain walls that straddle the interelectrode gap, it is shown that a large number of different direct current resistance states can be created, in parallel‐plate thin film lithium niobate capacitors. Surprisingly, such microstructural manipulation can result in colossal changes in device resistance (over twelve orders of magnitude).

Symmetry-mode analysis has been used to construct the direct linkage between structure and properties for (anti)ferroelectric materials., Functional materials are of critical importance to electronic and smart devices. A deep understanding of the structure–property relationship is essential for designing new materials. In this work, instead of utilizing conventional atomic coordinates, a symmetry-mode approach is successfully used to conduct structure refinement of the neutron powder diffraction data of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics. This provides rich structural information that not only clarifies the controversial symmetry assigned to pure AgNbO3 but also explains well the detailed structural evolution of (1−x)AgNbO3–xLiTaO3 (0 ≤ x ≤ 0.09) ceramics, and builds a comprehensive and straightforward relationship between structural distortion and electrical properties. It is concluded that there are four relatively large-amplitude major modes that dominate the distorted Pmc21 structure of pure AgNbO3, namely a Λ3 antiferroelectric mode, a T4+ a − a − c 0 octahedral tilting mode, an H2 a 0 a 0 c +/a 0 a 0 c − octahedral tilting mode and a Γ4− ferroelectric mode. The H2 and Λ3 modes become progressively inactive with increasing x and their destabilization is the driving force behind the composition-driven phase transition between the Pmc21 and R3c phases. This structural variation is consistent with the trend observed in the measured temperature-dependent dielectric properties and polarization–electric field (P-E) hysteresis loops. The mode crystallography applied in this study provides a strategy for optimizing related properties by tuning the amplitudes of the corresponding modes in these novel AgNbO3-based (anti)ferroelectric materials.

A series of bent‐shaped 4‐cyanoresorcinol bisterephthalates is reported. Some of these achiral compounds spontaneously form a short‐pitch heliconical lamellar liquid‐crystalline phase with incommensurate 3‐layer pitch and the helix axis parallel to the layer normal. It is observed at the paraelectric‐(anti)ferroelectric transition, if it coincides with the transition from random to uniform tilt and with the transition from anticlinic to synclinic tilt correlation of the molecules in the layers of the developing tilted smectic phase. For compounds with long chains the heliconical phase is only field‐induced, but once formed it is stable in a distinct temperature range, even after switching off the field. The presence of the helix changes the phase properties and the switching mechanism from the naturally preferred rotation around the molecular long axis, which reverses the chirality, to a precession on a cone, which retains the chirality. These observations are explained by diastereomeric relations between two coexisting modes of superstructural chirality. One is the layer chirality, resulting from the combination of tilt and polar order, and the other one is the helical twist evolving between the layers. At lower temperature the helical structure is replaced by a non‐tilted and ferreoelectric switching lamellar phase, providing an alternative non‐chiral way for the transition from anticlinic to synclinic tilt., Mirror symmetry breaking in fluids: Achiral bent‐shaped molecules form a spontaneous or field induced short‐pitch heliconical lamellar liquid‐crystalline phase. The combination of the helix with the superstructural layer chirality leads to diastereomeric pairs and changes the switching mechanism from the naturally preferred rotation around the molecular long axis, inverting the layer chirality, to a precession on a cone, retaining the chirality.