Abstract: Refractive optical element designs are provided for high geometric optical efficiency over a wide range of incident angles. To minimize Fresnel reflection losses, the refractive optical element designs employ multiple encapsulant materials, differing in refractive index. Concentrator photovoltaic subassemblies are formed by embedding a high efficiency photovoltaic device within the refractive optical element, along with appropriate electrical contacts and heat sinks. Increased solar electric power output is obtained by employing a single-junction III-V material structure with light-trapping structures.

Abstract: A photovoltaic (PV) device having a quantum dot sensitized interface includes a first conductor layer and a second conductor layer. At least one of the conductor layers is transparent to solar radiation. A quantum dot (nanoparticle) sensitized photo-harvesting interface comprises a photo-absorber layer, a quantum dot layer and a buffer layer, placed between the two conductors. The absorber layer is a p-type material and the buffer layer is an n-type material. The quantum dot layer has a tunable bandgap to cover infrared (IR), visible light and ultraviolet (UV) bands of solar spectrum.

Abstract: Optically-thin, quantum-structured solar cells incorporating III-V quantum wells or quantum dots have the potential to revolutionize the performance of photovoltaic devices. Enhanced spectral response characteristics have been widely demonstrated in both quantum well and quantum dot solar cells using a variety of different III-V materials. To fully leverage the extended spectral response of quantum-structured solar cells, new device designs are disclosed that can both maximize the current generating capability of the limited volume of narrow band gap material and minimize the unwanted carrier recombination that degrades the voltage output.

Abstract: Refractive optical element designs are provided for high geometric optical efficiency over a wide range of incident angles. To minimize Fresnel reflection losses, the refractive optical element designs employ multiple encapsulant materials, differing in refractive index. Concentrator photovoltaic subassemblies are formed by embedding a high efficiency photovoltaic device within the refractive optical element, along with appropriate electrical contacts and heat sinks. Increased solar electric power output is obtained by employing a single-junction III-V material structure with light-trapping structures.

Abstract: A photovoltaic (PV) device having a quantum dot sensitized interface includes a first conductor layer and a second conductor layer. At least one of the conductor layers is transparent to solar radiation. A quantum dot (nanoparticle) sensitized photo-harvesting interface comprises a photo-absorber layer, a quantum dot layer and a buffer layer, placed between the two conductors. The absorber layer is a p-type material and the buffer layer is an n-type material. The quantum dot layer has a tunable bandgap to cover infrared (IR), visible light and ultraviolet (UV) bands of solar spectrum.

Abstract: The invention described herein details flexible, high-efficiency photovoltaic cells with nano-enhanced absorbers and ultra-low dark current. By extending infrared absorption, power conversion efficiencies in single-junction, nano-enhanced solar cells can potentially meet or even exceed the Shockley-Queisser limit. Novel device designs utilizing advanced band gap engineering are employed to suppress non-radiative recombination and expose the limiting radiative component of the dark current. Light trapping structures and new nanostructured absorber designs are also considered to maximize the creation and collection of photogenerated carriers. Flexible photovoltaic devices are fabricated using established full-wafer epitaxial liftoff processes. The innovative design described herein provides for light-weight and flexible photovoltaic sheets capable of achieving ultra-high conversion efficiencies over a wide range of operating conditions.

Abstract: Durable hydrophobic antireflection structures for optical elements, optical windows, and front sheets of encapsulated photovoltaic and photonic devices are disclosed which can minimize reflection losses over the entire accessible portion of the solar spectrum simultaneously provide self-cleaning and finger-print-free surface. Reduced reflectance and self-cleaning surfaces are resulted from coating the front sheet of encapsulated device with combination of nonporous and porous nanostructured materials such as silicon dioxide nanorods and PTFE. Step-graded antireflection structures can exhibit excellent omnidirectional performance, significantly outperforming conventional quarter wavelength and low-high-low refractive index coatings. Methods of constructing nanostructured durable optical coatings with hydrophobic surfaces are disclosed that can cover large-area ridged and flexible substrates.

Abstract: A method for fabricating a solar cell commences by bonding a first metal-coated substrate to a second metal-coated substrate to provide a bonded substrate. The bonded substrate is then coated with a first precursor solution to provide a coated bonded substrate. Finally, the procedure de-bonds the coated bonded substrate to provide a first solar cell device and a second solar cell device. A system for fabricating the solar cell comprises a first precursor solution deposition system containing a first precursor solution for deposition on a substrate, a first heating element for heating the substrate after deposition of the first precursor solution, a second precursor solution deposition system containing a second precursor solution for deposition on the substrate, and a second heating element for heating the substrate after deposition of the second precursor solution.

Abstract: Photon absorption, and thus current generation, is hindered in conventional thin-film solar cell designs, including quantum well structures, by the limited path length of incident light passing vertically through the device. Optical scattering into lateral waveguide structures provides a physical mechanism to increase photocurrent generation through in-plane light trapping. However, the insertion of wells of high refractive index material with lower energy gap into the device structure often results in lower voltage operation, and hence lower photovoltaic power conversion efficiency. The voltage output of an InGaAs quantum well waveguide photovoltaic device can be increased by employing a III-V material structure with an extended wide band gap emitter heterojunction.

Abstract: This invention provides a portable system for the generation of photovoltaic energy. The power plant is provided as a kit in a plurality of containers, each of which can be carried by one person. This power plant can be assembled in a few hours by two people. The power plant is adjustable and can adapt to a variety of locations and environments. The power plant includes a frame structure, a movable photovoltaic collection array of more than one solar panel, a power management module, battery power storage system and various cables. The power plant can include shelving and can function as a vehicle port. The photovoltaic collection array can be pivotally raised and lowered for optimal solar power collection manually or mechanically. In further embodiments, more than one such power plant can be joined together to create a portable local power grid.

Abstract: Ultra-high reflectivity is projected for internal reflectors comprised of a metal film and nanostructured transparent conductive oxide (TCO) bi-layer on the back side of a semiconductor device. Oblique-angle deposition can be used to fabricate indium tin oxide (ITO) and other TCO optical thin-film coatings with a porous, columnar nanostructure. The resulting low-n dielectric films can then be employed as part of a conductive omni-directional reflector (ODR) structure capable of achieving high internal reflectivity over a broad spectrum of wavelengths and a wide range of angles. In addition, the dimensions and geometry of the nanostructured, low-n TCO films can be adjusted to enable diffuse reflections via Mie scattering. Diffuse ODR structures enhance the performance of light trapping and light guiding structures in photonic devices.

Abstract: A solar cell employing nanocrystalline superlattice material and amorphous structure and method of constructing the same provides improved efficiency when converting sunlight to power. The photovoltaic (PV) solar cell includes an intrinsic superlattice material deposited between the p-doped layer and the n-doped layer. The superlattice material is comprised of a plurality of sublayers which effectively create a graded band gap and multi-band gap for the superlattice material. The sublayers can include a nanocrystalline Si:H layer, an amorphous SiGe:H layer and an amorphous SiC:H layer. Varying the thickness of each layer results in an effective energy gap that is graded as desired for improved efficiency. Methods of constructing single junction and parallel configured two junction solar cells include depositing the various layers on a substrate such as stainless steel or glass.

Abstract: A photovoltaic (PV) device having a quantum dot sensitized interface includes a first conductor layer and a second conductor layer. At least one of the conductor layers is transparent to solar radiation. A quantum dot (nanoparticle) sensitized photo-harvesting interface comprises a photo-absorber layer, a quantum dot layer and a buffer layer, placed between the two conductors. The absorber layer is a p-type material and the buffer layer is an n-type material. The quantum dot layer has a tunable bandgap to cover infrared (IR), visible light and ultraviolet (UV) bands of solar spectrum.

Abstract: A photovoltaic device comprises a back reflective coating structure to provide back scattering of light that passes through the photovoltaic device, an absorber structure containing chalcogenide materials, and a top scattering antireflective structure deposited on the top subcell. Illustratively, a multi-junction structure comprises a bottom subcell deposited on the back reflective coating structure, the bottom subcell having a lower band gap, higher index material embedded therein, to provide lateral propagation of light that passes through the photovoltaic device, and a top subcell deposited on the bottom subcell. The multi-junction structure can comprise chalcogenide materials, in which case the top subcell is embedded with an intermediate band gap absorber material.

Abstract: Material and antireflection structure and methods of manufacturing are provided that produce efficient photovoltaic power conversion from thin film solar cells on flexible substrates. Step-graded antireflection structures are placed on the front of the device structure. Materials of different energy gap are combined in the depletion region of at least one of the semiconductor junctions within the thin film device structure. Conductive, low refractive index layers are deposited on the bottom of the thin film device structure to form an omni-directional back reflector contact.

Abstract: Material and antireflection structure designs and methods of manufacturing are provided that produce efficient photovoltaic power conversion from single- and multi-junction devices. Materials of different energy gap are combined in the depletion region of at least one of the semiconductor junctions. Higher energy gap layers are positioned to reduce the diode dark current and enhance the operating voltage by suppressing both carrier injections across the junction and recombination rates within the junction. Step-graded antireflection structures are placed above the active region of the device in order to increase the photocurrent.

Abstract: Durable hydrophobic antireflection structures for optical elements, optical windows, and front sheets of encapsulated photovoltaic and photonic devices are disclosed which can minimize reflection losses over the entire accessible portion of the solar spectrum simultaneously provide self-cleaning and finger-print-free surface. Reduced reflectance and self-cleaning surfaces are resulted from coating the front sheet of encapsulated device with combination of nonporous and porous nanostructured materials such as silicon dioxide nanorods and PTFE. Step-graded antireflection structures can exhibit excellent omnidirectional performance, significantly outperforming conventional quarter wavelength and low-high-low refractive index coatings. Methods of constructing nanostructured durable optical coatings with hydrophobic surfaces are disclosed that can cover large-area ridged and flexible substrates.

Abstract: A material structure and device design are provided that produce efficient photovoltaic power conversion. Materials of different energy gap are combined in the depletion region of a semiconductor junction. A wider energy gap barrier layer is positioned to reduce the diode dark current by suppressing both carrier injection across the junction and recombination rates within the junction. Light guiding layers are placed above and below the active region of the device in order to enhance optical absorption in the lower energy gap material.

Abstract: A photovoltaic (PV) device having a quantum dot sensitized interface includes a first conductor layer and a second conductor layer. At least one of the conductor layers is transparent to solar radiation. A quantum dot (nanoparticle) sensitized photo-harvesting interface comprises a photo-absorber layer, a quantum dot layer and a buffer layer, placed between the two conductors. The absorber layer is a p-type material and the buffer layer is an n-type material. The quantum dot layer has a tunable bandgap to cover infrared (IR), visible light and ultraviolet (UV) bands of solar spectrum.

Abstract: A solar cell employing nanocrystalline superlattice material and amorphous structure and method of constructing the same provides improved efficiency when converting sunlight to power. The photovoltaic (PV) solar cell includes an intrinsic superlattice material deposited between the p-doped layer and the n-doped layer. The superlattice material is comprised of a plurality of sublayers which effectively create a graded band gap and multi-band gap for the superlattice material. The sublayers can include a nanocrystalline Si:H layer, an amorphous SiGe:H layer and an amorphous SiC:H layer. Varying the thickness of each layer results in an effective energy gap that is graded as desired for improved efficiency. Methods of constructing single junction and parallel configured two junction solar cells include depositing the various layers on a substrate such as stainless steel or glass.