Abstract: Methods are described for forming CIGS absorber layers in TFPV devices with graded compositions and graded band gaps. Methods are described for utilizing Al to increase the band gap at the front surface of the absorber layer. Methods are described for forming a Cu—In—Ga layer followed by partial or full selenization. This results in a higher Ga concentration at the back interface. The substrate is then exposed to an aluminum CVD precursor while the substrate is still in the selenization equipment to deposit a thin Al layer. The substrate is then exposed to a Se source to fully convert the absorber layer. This results in a higher Al concentration at the front of the absorber.

Abstract: Optical absorbers and methods are disclosed. The methods comprise depositing a plurality of precursor layers comprising one or more of Cu, Ga, and In on a substrate, and heating the layers in a chalcogenizing atmosphere. The plurality of precursor layers can be one or more sets of layers comprising at least two layers, wherein each layer in each set of layers comprises one or more of Cu, Ga, and In exhibiting a single phase. The layers can be deposited using two or three targets selected from Ag and In containing less than 21% In by weight, Cu and Ga where the Cu and Ga target comprises less than 45% Ga by weight, Cu(In,Ga), wherein the Cu(In,Ga) target has an atomic ratio of Cu to (In+Ga) greater than 2 and an atomic ratio of Ga to (Ga+In) greater than 0.5, elemental In, elemental Cu, and In2Se3 and In2S3.

Abstract: The present disclosure provides a thermoelectric element comprising a flexible semiconductor substrate having exposed surfaces with a metal content that is less than about 1% as measured by x-ray photoelectron spectroscopy (XPS) and a figure of merit (ZT) that is at least about 0.25, wherein the flexible semiconductor substrate has a Young's Modulus that is less than or equal to about 1×106 pounds per square inch (psi) at 25° C.

Abstract: In some embodiments, Cu—In—Ga precursor films are deposited by co-sputtering from multiple targets. Specifically, the co-sputtering method is used to form layers that include In. The co-sputtering reduces the tendency for the In component to agglomerate and results in smoother, more uniform films. In some embodiments, the Ga concentration in one or more target(s) is between about 25 atomic % and about 66 atomic %. The deposition may be performed in a batch or in-line deposition system. If an in-line deposition system is used, the movement of the substrates through the system may be continuous or may follow a “stop and soak” method of substrate transport.

Abstract: Solar cells and methods for forming a back contact layer for a solar cell are disclosed. The methods comprise depositing a first layer comprising a conductor on a substrate, depositing a second layer on the first layer, the second layer comprising between about 1 nm and about 25 nm of a metal chalcogenide, and forming a third layer operable as an absorber layer on the second layer. The absorber layer can comprise a photoactive semiconductor layer. In some embodiments, the absorber layer comprises a chalcogenide of copper-indium-gallium. In some embodiments, the absorber layer comprises a chalcogenide of copper-zinc-tin. In some embodiments, the absorber layer comprises CdTe. In some embodiments, the metal comprises Mo, W or Ta. In some embodiments, the metal comprises Mo. In some embodiments, the chalcogenide comprises S or Se or a combination thereof.

Abstract: Optical absorbers, solar cells comprising the absorbers, and methods for making the absorbers are disclosed. The optical absorber comprises a semiconductor layer having a bandgap of between about 1.0 eV and about 1.6 eV disposed on a substrate, wherein the semiconductor comprises two or more earth abundant elements. The bandgap of the optical absorber is graded through the thickness of the layer by partial substitution of at least one grading element from the same group in the periodic table as the at least one of the two or more earth abundant elements.

Abstract: Methods of forming absorber layers in a TFPV device are provided. Methods are described to provide the formation of metal oxide films and heating the metal oxide films in the presence of a chalcogen to form a metal-oxygen-chalcogen alloy. Methods are described to provide the formation of metal oxide films, forming a layer of elemental chalcogen on the metal oxide film, and heating the stack to form a metal-oxygen-chalcogen alloy. In some embodiments, the metal oxide film includes zinc oxide and the chalcogen includes selenium.

Abstract: A thermal processing apparatus and method in which a first laser source, for example, a CO2 emitting at 10.6 ?m is focused onto a silicon wafer as a line beam and a second laser source, for example, a GaAs laser bar emitting at 808 nm is focused onto the wafer as a larger beam surrounding the line beam. The two beams are scanned in synchronism in the direction of the narrow dimension of the line beam to create a narrow heating pulse from the line beam when activated by the larger beam. The energy of GaAs radiation is greater than the silicon bandgap energy and creates free carriers. The energy of the CO2 radiation is less than the silicon bandgap energy so silicon is otherwise transparent to it, but the long wavelength radiation is absorbed by the free carriers.

Abstract: Methods for increasing the power output of a TFPV solar panel using thin absorber layers comprise techniques for roughening and/or texturing the back contact layer. The techniques comprise roughening the substrate prior to the back contact deposition, embedding particles in sol-gel films formed on the substrate, and forming multicomponent, polycrystalline films that result in a roughened surface after a wet etch step, etc.

Abstract: A gallium-containing alloy is formed on the light-receiving surface of a CIGS absorber layer, and, in conjunction with a subsequent selenization or anneal process, is converted to a gallium-rich region at the light-receiving surface of the CIGS absorber layer. A second gallium-rich region is formed at the back contact surface of the CIGS absorber layer during selenization, so that the CIGS absorber layer has a double-graded gallium concentration that increases toward the light-receiving surface and toward the back contact surface of the CIGS absorber layer. The double-graded gallium concentration advantageously produces a double-graded bandgap profile for the CIGS absorber layer.

Abstract: A gallium-containing alloy is formed on the light-receiving surface of a CIGS absorber layer, and, in conjunction with a subsequent selenization or anneal process, is converted to a gallium-rich region at the light-receiving surface of the CIGS absorber layer. A second gallium-rich region is formed at the back contact surface of the CIGS absorber layer during selenization, so that the CIGS absorber layer has a double-graded gallium concentration that increases toward the light-receiving surface and toward the back contact surface of the CIGS absorber layer. The double-graded gallium concentration advantageously produces a double-graded bandgap profile for the CIGS absorber layer.

Abstract: A thermal processing apparatus and method in which a first laser source, for example, a CO2 emitting at 10.6 ?m is focused onto a silicon wafer as a line beam and a second laser source, for example, a GaAs laser bar emitting at 808 nm is focused onto the wafer as a larger beam surrounding the line beam. The two beams are scanned in synchronism in the direction of the narrow dimension of the line beam to create a narrow heating pulse from the line beam when activated by the larger beam. The energy of GaAs radiation is greater than the silicon bandgap energy and creates free carriers. The energy of the CO2 radiation is less than the silicon bandgap energy so silicon is otherwise transparent to it, but the long wavelength radiation is absorbed by the free carriers.

Abstract: A method is disclosed for fabricating high efficiency CIGS solar cells including the deposition of a multi-component metal precursor film on a substrate. The substrate is then inserted into a system suitable for exposing the precursor to a chalcogen to form a chalcogenide TFPV absorber. One or more Na precursors are used to deposit a Na-containing layer on the precursor film in the system. This method eliminates the use of dedicated equipment and processes for introducing Na to the TFPV absorber.

Abstract: A thermal processing apparatus and method in which a first laser source, for example, a CO2 emitting at 10.6 ?m is focused onto a silicon wafer as a line beam and a second laser source, for example, a GaAs laser bar emitting at 808 nm is focused onto the wafer as a larger beam surrounding the line beam. The two beams are scanned in synchronism in the direction of the narrow dimension of the line beam to create a narrow heating pulse from the line beam when activated by the larger beam. The energy of GaAs radiation is greater than the silicon bandgap energy and creates free carriers. The energy of the CO2 radiation is less than the silicon bandgap energy so silicon is otherwise transparent to it, but the long wavelength radiation is absorbed by the free carriers.

Abstract: A method for fabricating high efficiency CIGS solar cells including the deposition of Ga concentrations (Ga/(Ga+In)=0.25-0.66) from sputtering targets containing Ga concentrations between about 25 atomic % and about 66 atomic %. Further, the method includes a high temperature selenization process integrated with a high temperature anneal process that results in high efficiency.

Abstract: A method for high temperature selenization of Cu—In—Ga metal precursor films comprises ramping the precursor film to a temperature between about 300 C and about 400 C in a Se containing atmosphere and at a pressure between about 600 torr and 800 torr. A partial selenization is performed at a temperature between about 300 C and about 400 C in a Se-containing atmosphere. The film is then ramped to a temperature between about 400 C and about 550 C in a Se containing atmosphere and at a pressure between about 600 torr and 800 torr. The film is then annealed at a temperature between about 550 C and about 650 C in an inert gas.

Abstract: A method for fabricating high efficiency CIGS solar cells including the deposition of Ga concentrations (Ga/(Ga+In)=0.25?0.66) from sputtering targets containing Ga concentrations between about 25 atomic % and about 66 atomic %. Further, the method includes a high temperature selenization process integrated with a high temperature anneal process that results in high efficiency.

Abstract: A method for high temperature selenization of Cu—In—Ga metal precursor films comprises ramping the precursor film to a temperature between about 350 C and about 450 C in an inert gas and at a pressure between about 1 atmosphere and about 2 atmospheres. A partial selenization is performed at a temperature between about 350 C and about 450 C in a Se-containing atmosphere. The film is then ramped to a temperature between about 450 C and about 550 C in an inert gas and at a pressure between about 1 atmosphere and about 2 atmospheres, followed by an additional selenization step at a temperature between about 450 C and about 550 C in a Se-containing atmosphere. The film is then annealed at a temperature between about 550 C and about 650 C in an inert gas.

Abstract: Methods for increasing the power output of a TFPV solar panel using thin absorber layers comprise techniques for roughening and/or texturing the back contact layer. The techniques comprise roughening the substrate prior to the back contact deposition, embedding particles in sol-gel films formed on the substrate, and forming multicomponent, polycrystalline films that result in a roughened surface after a wet etch step, etc.

Abstract: A gallium-containing alloy is formed on the light-receiving surface of a CIGS absorber layer, and, in conjunction with a subsequent selenization or anneal process, is converted to a gallium-rich region at the light-receiving surface of the CIGS absorber layer. A second gallium-rich region is formed at the back contact surface of the CIGS absorber layer during selenization, so that the CIGS absorber layer has a double-graded gallium concentration that increases toward the light-receiving surface and toward the back contact surface of the CIGS absorber layer. The double-graded gallium concentration advantageously produces a double-graded bandgap profile for the CIGS absorber layer.