Abstract: Described herein are materials and systems for efficient upconversion of photons. The materials may be disposed in a system comprising two semiconductor materials with an interface therebetween, the interface comprising a valence and/or conduction band offset between the semiconducting materials of about ?0.5 eV to about 0.5 eV, including 0, wherein one of the semiconductor materials is a material with discrete energy states and the other is a material with a graded composition and/or controlled band gap. The system can upconvert photons by: a) controlling energy levels of discrete energy states of a semiconducting material in a system to direct tunneling and exciton separation; b) controlling a compositional profile of another semiconducting material in the system to funnel charges away from an upconversion region and into a recombination zone; and c) utilizing the discrete energy states of the semiconducting material in the system to inhibit phonon relaxation.

Abstract: Described herein are materials and systems for efficient upconversion of photons. The materials may be disposed in a system comprising two semiconductor materials with an interface therebetween, the interface comprising a valence and/or conduction band offset between the semiconducting materials of about ?0.5 eV to about 0.5 eV, including 0, wherein one of the semiconductor materials is a material with discrete energy states and the other is a material with a graded composition and/or controlled band gap. The system can upconvert photons by: a) controlling energy levels of discrete energy states of a semiconducting material in a system to direct tunneling and exciton separation; b) controlling a compositional profile of another semiconducting material in the system to funnel charges away from an upconversion region and into a recombination zone; and c) utilizing the discrete energy states of the semiconducting material in the system to inhibit phonon relaxation.

Abstract: A self-contained interactive video display system. A projector projects a visual image onto a screen for displaying the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen. An illuminator illuminates an object near the front side of the screen. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable to the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction.

Abstract: A self-contained interactive video display system. A projector projects a visual image onto a screen for displaying the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen. An illuminator illuminates an object near the front side of the screen. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable to the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction.

Abstract: An interactive video window display system. A projector projects a visual image. A screen displays the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen, and wherein the screen is adjacent to a window. An illuminator illuminates an object on a front side of the window. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable by the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction. The projector, the camera, the illuminator, and the computer system are located on the same side of the window.

Abstract: An interactive video window display system. A projector projects a visual image. A screen displays the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen, and wherein the screen is adjacent to a window. An illuminator illuminates an object on a front side of the window. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable by the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction. The projector, the camera, the illuminator, and the computer system are located on the same side of the window.

Abstract: An interactive video window display system. A projector projects a visual image. A screen displays the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen, and wherein the screen is adjacent to a window. An illuminator illuminates an object on a front side of the window. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable by the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction. The projector, the camera, the illuminator, and the computer system are located on the same side of the window.

Abstract: A self-contained interactive video display system. A projector projects a visual image onto a screen for displaying the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen. An illuminator illuminates an object near the front side of the screen. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable to the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction.

Abstract: Composite epitaxial materials that comprise semimetallic ErAs nanoparticles or nanoislands epitaxially embedded in a semiconducting In0.53Ga0.47As matrix both as superlattices and randomly distributed throughout the matrix are disclosed. The presence of these particles increases the free electron concentration in the material while providing scattering centers for phonons. Electron concentration, mobility, and Seebeck coefficient of these materials are discussed and their potential for use in thermoelectric power generators is postulated. These composite materials in accordance with the present invention have high electrical conductivity, low thermal conductivity, and a high Seebeck coefficient. The ErAs nanoislands provides additional scattering mechanism for the mid to long wavelength phonon—the combination reduces the thermal conductivity below the alloy limit.

Abstract: A method and device that incorporates metallic nanoparticles at the p+-n+ tunnel junction in a cascaded photovoltaic solar cell. The use of the nanoparticles enhances the tunneling current density through the tunnel junction. As such, the efficiency of the solar cell is increased. A method in accordance with the present invention comprises making a first solar cell having a first bandgap, making a tunnel junction coupled to the first solar cell, and making a second solar cell having a second bandgap, coupled to the tunnel junction opposite the first solar cell, wherein the tunnel junction comprises nanoparticles. Such a method further optionally includes the nanoparticles being a metal or a semi metal, specifically a semi-metal of erbium arsenide, the nanoparticles being deposited in an island structure within the tunnel junction, and the first solar cell being deposited on a flexible substrate.

Abstract: A self-contained interactive video display system. A projector projects a visual image onto a screen for displaying the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen. An illuminator illuminates an object near the front side of the screen. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable to the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction.

Abstract: A self-contained interactive video display system. A flat-panel display screen displays a visual image for presentation to a user on a front side of the flat-panel display screen. A first illuminator illuminates the flat-panel display screen with visible light. A second illuminator illuminates an object. A camera detects interaction of an illuminated object with the visual image, wherein the camera is operable to view the object through the flat-panel display screen. A computer system directs the projector to change the visual image in response to the interaction.

Abstract: An interactive video window display system. A projector projects a visual image. A screen displays the visual image, wherein the projector projects the visual image onto a back side of the screen for presentation to a user on a front side of the screen, and wherein the screen is adjacent to a window. An illuminator illuminates an object on a front side of the window. A camera detects interaction of an illuminated object with the visual image, wherein the screen is at least partially transparent to light detectable by the camera, allowing the camera to detect the illuminated object through the screen. A computer system directs the projector to change the visual image in response to the interaction. The projector, the camera, the illuminator, and the computer system are located on the same side of the window.