Abstract: The present disclosure is directed to using MXene compositions as templates for the deposition of oriented perovskite films, and compositions derived from such methods. Certain specific embodiments include methods preparing an oriented perovskite, perovskite-type, or perovskite-like film, the methods comprising: (a) depositing at least one perovskite, perovskite-type, or perovskite-like composition or precursor composition using chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD) onto a film or layer of a MXene composition supported on a substrate to form a layered composition or precursor composition; and either (b) (1) heat treating or annealing the layered precursor composition to form a layered perovskite-type structure comprising at least one oriented perovskite, perovskite-type, or perovskite-like composition; or (2) annealing the layered composition; or (3) both (1) and (2).

Abstract: The present disclosure provides a layering structure that permits integration of epitaxially oriented perovskite oxides, such as bismuth ferrite (BiFeO3), epitaxially oriented barium titanate (BaTiO3), epitaxially oriented (SrTiO3), or their superstructures (BTO/STO) or solid solutions, onto a Si substrate through a perovskite buffer layer. The structure can retain thermal process-sensitive dopant positions and other thermal process window-sensitive features through atomic layer deposition of an oxide perovskite. Also provided are methods of preparing these layered structures.

Abstract: Provided is the dielectric response of atomic layer-deposited and annealed polymorphic BaTiO3 and BaTiO3—AlO3 bi-layer thin films based on nanocrystalline BaTiO3 containing the perovskite and hexagonal polymorphs. Also provided are BaTiCb films having tuned Curie temperatures. Also provide are nano-grained films, comprising: a BaTiO3 film component comprising a Ba/Ti ratio of between about 0.8 and 1.06, a transition temperature of the nano-grained film being dependent on the Ba/Ti ratio, and the nano-grained film exhibiting a diffused phase transition, optionally whereby a temperature density of a dielectric constant of the nano-grained film is minimized.

Abstract: Provided is the dielectric response of atomic layer-deposited and annealed polymorphic BaTiO3 and BaTiO3—Al2O3 bi-layer thin films based on nanocry stalline BaTiO3 containing the perovskite and hexagonal polymorphs. Also provided are BaTiO3 films having tuned Curie temperatures. Further provided are capacitive components, comprising: a plurality of films, the plurality of films comprising: a first grained film component, the first grained film component comprising at least one of SrTiO3, BaTiO3, and (Ba, Sr)TiO3, and the first grained film component being characterized as being at least partially polymorphic crystalline in nature; a second film component contacting the first grained film component, the second film component optionally comprising Al2O3, and the first grained film component optionally defining an average grain size of less than about 10 micrometers.

Abstract: The present disclosure describes a strained dielectric material comprising at least one type of component containing a domain wall variant pattern, or superdomain structure, that is in phase-co-existence with, or in close phase proximity to, a paraelectric state achieved at zero electric field or over a finite range of non-zero electric field, wherein the at least one type of component comprises one or more of an in-plane sub-domain polarization component, a plane-normal sub-domain polarization component, or a solid solution of a ferroelectric.

Abstract: An article comprising a ferroelectric material in its ferroelectric phase, wherein the article is configured to enable low-loss propagation of signals with ultra-low dielectric loss at one or more select frequencies.

Abstract: The present invention is directed to photovoltaic and photogalvanic devices and methods of generating electrical energy and power or detecting light therefrom, based on a novel nano-enhanced bulk photovoltaic effect using non-centrosymmetric crystals, including ferroelectric and piezoelectric materials, where the non-centrosymmetry is the equilibrium state or it is static or dynamically induced. In certain embodiments, the device comprises a layer of non-centrosymmetric crystalline materials, and a plurality of electrodes disposed in an array upon or penetrating into at least one surface of the crystalline material, the electrodes being optimally spaced to capture the ballistic carriers generated upon irradiation of the crystalline material.

Abstract: A method of growing a FE material thin film using physical vapor deposition by pulsed laser deposition or RF sputtering is disclosed. The method involves creating a target to be used for the pulsed laser deposition in order to create a KBNNO thin film. The resultant KBNNO thin film is able to be used in photovoltaic cells.

Abstract: The present disclosure is directed to using MXene compositions as templates for the deposition of oriented perovskite films, and compositions derived from such methods. Certain specific embodiments include methods preparing an oriented perovskite, perovskite-type, or perovskite-like film, the methods comprising: (a) depositing at least one perovskite, perovskite-type, or perovskite-like composition or precursor composition using chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD) onto a film or layer of a MXene composition supported on a substrate to form a layered composition or precursor composition; and either (b) (1) heat treating or annealing the layered precursor composition to form a layered perovskite-type structure comprising at least one oriented perovskite, perovskite-type, or perovskite-like composition; or (2) annealing the layered composition; or (3) both (1) and (2).

Abstract: The present invention is directed to photovoltaic and photogalvanic devices and methods of generating electrical energy and power or detecting light therefrom, based on a novel nano-enhanced bulk photovoltaic effect using non-centrosymmetric crystals, including ferroelectric and piezoelectric materials, where the non-centrosymmetry is the equilibrium state or it is static or dynamically induced. In certain embodiments, the device comprises a layer of non-centrosymmetric crystalline materials, and a plurality of electrodes disposed in an array upon or penetrating into at least one surface of the crystalline material, the electrodes being optimally spaced to capture the ballistic carriers generated upon irradiation of the crystalline material.

Abstract: A ferroelectric perovskite composition, comprising a perovskite oxide ABO3, and a doping agent selected from perovskites of Ba(Ni,Nb)O3 and Ba(Ni,Nb)O3-?. The ferroelectric perovskite composition may be represented by the formula: xBa(Ni,Nb)O3.(1-x)ABO3 or xBa(Ni,Nb)O3-?.(1-x)ABO3. A method of producing the ferroelectric perovskite composition in thin film form is also provided.

Abstract: A method of growing a FE material thin film using physical vapor deposition by pulsed laser deposition or RF sputtering is disclosed. The method involves creating a target to be used for the pulsed laser deposition in order to create a KBNNO thin film. The resultant KBNNO thin film is able to be used in photovoltaic cells.

Abstract: The present disclosure pertains to the use of intense, narrow-linewidth surface, chemically-switchable ultraviolet photoluminescence from radiative recombination of the two-dimensional electron liquid with photo-excited holes in complex oxide heterostructures, such as LaAlO3/SrTiO3 (LAO/STO). Such photoluminescence from the interface between the upper and lower layers can be suppressed and restored reversibly under oxidizing and reducing conditions, respectively, as induced by chemisorption and reversal of chemisorption on the exposed surface of the heterostructure's upper member. Making use of this chemically-switchable ultraviolet photoluminescence, the present disclosure provides, inter alia, systems for detection of a chemical species, methods for determining the absence or presence of a chemical species in a sample, optoelectronic devices, and methods for producing optoelectronic devices.

Abstract: Disclosed herein are nanoscale devices comprising one or more ferroelectric nanoshells characterized as having an extreme curvature in at least one spatial dimension. Also disclosed are ferroelectric field effect transistors and metal ferroelectric metal capacitors comprising one or more ferroelectric nanoshells. Methods for controlling spontaneous ferroelectric polarization in nanoshell devices are also disclosed.

Abstract: Disclosed herein are ferroelectric perovskites characterized as having a band gap, Egap, of less than 2.5 eV. Also disclosed are compounds comprising a solid solution of KNbO3 and BaNi1/2Nb1/2O3-delta, wherein delta is in the range of from 0 to about 1. The specification also discloses photovoltaic devices comprising one or more solar absorbing layers, wherein at least one of the solar absorbing layers comprises a semiconducting ferroelectric layer. Finally, this patent application provides solar cell, comprising: a heterojunction of n- and p-type semiconductors characterized as comprising an interface layer disposed between the n- and p-type semiconductors, the interface layer comprising a semiconducting ferroelectric absorber layer capable of enhancing light absorption and carrier separation.

Abstract: This disclosure provides methods for forming a perovskite film. Exemplary methods can include the steps of forming an amorphous layer on a substrate disposed in a reaction chamber, covering at least a portion of the amorphous layer with a barrier that at least partially prevents the first metal, the second metal, oxygen atoms, or a combination thereof from being released during annealing and annealing the amorphous layer to form a perovskite film. Formation of the amorphous layer on the substrate disposed in a reaction chamber may be effected by introducing a first compound comprising a first metal; introducing an oxidizing agent; and introducing a second compound comprising a second metal.

Abstract: Disclosed herein are nanoscale devices comprising one or more ferroelectric nanoshells characterized as having an extreme curvature in at least one spatial dimension. Also disclosed are ferroelectric field effect transistors and metal ferroelectric metal capacitors comprising one or more ferroelectric nanoshells. Methods for controlling spontaneous ferroelectric polarization in nanoshell devices are also disclosed.

Abstract: Disclosed herein are nanoscale devices comprising one or more ferroelectric nanoshells characterized as having an extreme curvature in at least one spatial dimension. Also disclosed are ferroelectric field effect transistors and metal ferroelectric metal capacitors comprising one or more ferroelectric nanoshells. Methods for controlling spontaneous ferroelectric polarization in nanoshell devices are also disclosed.

Abstract: Provided are multimaterial devices, such as coaxial nanowires, that effect hot photoexcited electron transfer across the interface of the materials. Modulation of the transfer rates, manifested as a large tunability of the voltage onset of negative differential resistance and of voltage-current phase, may be effected by modulating electrostatic gating, incident photon energy, and the incident photon intensity. Dynamic manipulation of this transfer rate permits the introduction and control of an adjustable phase delay within a device element.

Abstract: Disclosed herein are nanoscale devices comprising one or more ferroelectric nanoshells characterized as having an extreme curvature in at least one spatial dimension. Also disclosed are ferroelectric field effect transistors and metal ferroelectric metal capacitors comprising one or more ferroelectric nanoshells. Methods for controlling spontaneous ferroelectric polarization in nanoshell devices are also disclosed.