Patent Application
20140367250
A thin film solar (or photovoltaic) cell may be formed by depositing material layers on a substrate. Such material layers may include photoactive layers. Material layers may be deposited sequentially with the aid of deposition systems. A photovoltaic device structure may be formed following the deposition of various material layers, including an absorber of the photovoltaic device.
There are various depositions systems and methods for forming thin film photovoltaic cells. Such systems include vapor phase deposition systems and sputtering systems. Examples of deposition systems include roll-to-roll deposition systems.
While there are systems presently available for forming thin film solar (or photovoltaic) cells, recognized herein are various limitations associated with such systems. For instance, systems that use evaporation for the deposition of thin films and chemical vapor deposition systems may experience much more difficulty in maintaining compositional control than those that employ sputtering, and the deposition rates of such evaporation systems are typically lower that sputtering systems.
While there are sputtering systems (e.g., roll-to-roll sputtering systems) presently available for forming photovoltaic cells, such systems may not be capable of monitoring individual layers of a photovoltaic cell, since, for example, a given layer is interactive and formed simultaneously with other layers. Further, each station of a roll-to-roll sputtering system should work with high yield at all times or else some well formed layers will be compromised with poorly formed layers, lowering the net yield of the process as a whole. A failure in one part of the system necessitates stopping the entire roll-to-roll process, which can disadvantageously lead to downtime. Some roll-to-roll processes use substrate web payout and take up (or pickup) drums to support the substrate. A disadvantage of such processes can lead to limited substrate temperatures and increased difficulty in web handling for thin metallic substrates that have a much higher modulus than polymeric substrates.
In view of at least some of the herein-recognized limitations of systems and methods presently available for forming photovoltaic cells, what is needed are improved systems and methods for forming photovoltaic cells.
This disclosure provides roll coating systems having flexibility for depositing various layers of a thin film solar cell. A system for forming photovoltaic cells can include a plurality of modules, with each module configured to deposit one of the layers of the cell. As such, a problem with one layer can be corrected while production proceeds on the other machines. The present disclosure describes the architecture for a roll-to-roll coating machine which can overcome at least some of the disadvantages of current systems.
This disclosure provides sputter deposition systems and methods for coating materials on thin flexible substrates in roll form. Some embodiments provide sputtering apparatuses (e.g., mini chambers) and methods for forming various layers of thin film solar cells on rolls of thin flexible metallic substrates. Systems of the disclosure provide for the formation of photovoltaic cells in a relatively rapid and economical fashion.
This disclosure provides a machine that can be used to produce thin film solar cells faster and more economically than current equipment. Systems of the disclosure incorporate configuration flexibility that can accommodate the deposition of different layers of a thin film solar cell.
An aspect of the present disclosure provides a deposition system for depositing a thin film photovoltaic cell on a flexible substrate. The deposition system can comprise an enclosure comprising a fluid space that is fluidically isolated from an environment external to the enclosure, and a plurality of deposition chambers in the fluid space. At least one deposition chamber of the plurality of deposition chambers can comprise a magnetron sputtering apparatus that directs a material flux of one or more target materials towards a portion of the flexible substrate that is disposed in the at least one deposition chamber of the plurality of deposition chambers. The deposition system can further comprise a substrate payout roller and a substrate take-up roller in the enclosure. The substrate payout roller provides a flexible substrate that is directed through each of the plurality of deposition chambers to the substrate take-up roller. The deposition system can comprise at least one guide roller in the enclosure. The guide roller can be configured to direct the flexible substrate to or from a given deposition chamber among the plurality of deposition chambers.
Another aspect of the present disclosure provides a deposition system for depositing a thin film photovoltaic cell on a flexible substrate. The deposition system can comprise an enclosure comprising a fluid space that is fluidically isolated from an environment external to the enclosure, and a plurality of deposition chambers in the fluid space. The plurality of deposition chambers can comprise a first deposition chamber and a second deposition chamber. The first deposition chamber can comprise a magnetron sputtering apparatus that directs a first material flux towards a first side of a portion of the flexible substrate. The second deposition chamber can comprise a magnetron sputtering apparatus that directs a second material flux towards a second side of the portion that is opposite from the first side. The deposition system can further comprise a payout roller and a take-up roller in the enclosure. The payout roller can sequentially direct the flexible substrate to the take-up roller through each of the plurality of deposition chambers.
Another aspect of the present disclosure provides a method for depositing a photovoltaic cell device structure adjacent to a flexible substrate, comprising providing a deposition system comprising a plurality of deposition chambers in a sealed enclosure. At least one deposition chamber of the plurality of deposition chambers can comprise a magnetron sputtering apparatus that directs a material flux of one or more target materials towards a portion of the flexible substrate that is disposed in the at least one deposition chamber. The deposition system can further comprise a payout roller and a take-up roller in the enclosure, and at least one guide roller for directing the flexible substrate to or from a given deposition chamber among the plurality. Next, with the aid of the at least one guide roller, the flexible substrate can be directed from the payout roller through each of the plurality of deposition chambers in sequence to form the photovoltaic cell device structure adjacent to the flexible substrate. The flexible substrate can then be directed from the plurality of deposition chambers to the take-up roller.
Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
While various embodiments of the invention(s) of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention(s). It should be understood that various alternatives to the embodiments of the invention(s) described herein may be employed in practicing any one of the inventions(s) set forth herein.
The term “photovoltaic cell” or “solar cell,” as used herein, refers to a solid state electrical device having an active material (or absorber) that converts the energy of electromagnetic radiation (or light) into electricity by the photovoltaic (PV) effect.
The term “absorber,” as used herein, generally refers to a photoactive material that, upon exposure to electromagnetic radiation, converts the energy of electromagnetic radiation into electricity by the photovoltaic (PV) effect. An absorber can be configured to generate electricity at select wavelengths of light. An absorber layer can be configured to generate electron/hole pairs. Upon exposure to light, an absorber can generate electron/hole pairs. Examples of absorbers include, without limitation, copper indium gallium di-selenide (CIGS) and copper indium selenide (CIS). An absorber layer can be doped n-type or p-type. Some absorbers are n-type or p-type without any additional doping. For example, CIGS, as formed, can be p-type and may not require any additional p-type doping. In some cases, upon formation of the absorber layer (e.g., silicon absorber layer), a precursor of an n-type or p-type dopant is introduced for incorporating the n-type or p-type dopant into the absorber layer. As an alternative, following formation of the absorber layer, the n-type or p-type dopant can be introduced into the absorber layer by ion implantation followed by annealing. In some situations (e.g., CIGS), a sodium precursor is provided to the absorber layer to include sodium in the absorber layer.
The term “photovoltaic module” or “solar module,” as used herein, refers to a packaged array of one or more PV cells. The PV module (also “module” herein) can be used as a component of a larger photovoltaic system to generate and supply electricity, such as in commercial and residential applications. A PV module can include a support structure having one or more PV cells. In some embodiments, a PV module includes a plurality of PV cells, which can be interconnected, such as, for example, in series with the aid of interconnects. A PV array can include a plurality of PV modules.
The term “n-type,” as used herein, generally refers to a material that is chemically doped (“doped”) with an n-type dopant. For instance, silicon can be doped n-type using phosphorous or arsenic.
The term “p-type,” as used herein, generally refers to a material that is doped with an p-type dopant. For instance, silicon can be doped p-type using boron or aluminum.
The term “layer,” as used herein, generally refers to a layer of atoms or molecules on a substrate. In some cases, a layer includes an epitaxial layer or a plurality of epitaxial layers. A layer may include a film or thin film. In some situations, a layer is a structural component of a device (e.g., light emitting diode) serving a predetermined device function, such as, for example, an active layer that is configured to generate (or emit) light. A layer generally has a thickness from about one monolayer (ML) to tens of monolayers, hundreds of monolayers, thousands of monolayers, millions of monolayers, billions of monolayers, trillions of monolayers, or more. In an example, a layer is a multilayer structure having a thickness greater than one monolayer. In addition, a layer may include multiple material layers (or sub-layers). In an example, a multiple quantum well active layer includes multiple well and barrier layers. A layer may include a plurality of sub-layers. For example, an active layer may include a barrier sub-layer and a well sub-layer.
The term “substrate,” as used herein, generally refers to any workpiece on which a layer, film or thin film formation is desired. A substrate includes, without limitation, silicon, germanium, silica, sapphire, zinc oxide, carbon (e.g., graphene), SiC, AlN, GaN, spinel, coated silicon, silicon on oxide, silicon carbide on oxide, glass, gallium nitride, indium nitride, titanium dioxide and aluminum nitride, a ceramic material (e.g., alumina, AlN), a metallic material (e.g., stainless steel, tungsten, titanium, copper, aluminum), a polymeric material and combinations (or alloys) thereof.
The term “adjacent” or “adjacent to,” as used herein, includes ‘next to’, ‘adjoining’, ‘in contact with’, and ‘in proximity to’. In some instances, adjacent to components are separated from one another by one or more intervening layers. For example, the one or more intervening layers can have a thickness less than about 10 micrometers (“microns”), 1 micron, 500 nanometers (“nm”), 100 nm, 50 nm, 10 nm, 1 nm, or less. In an example, a first layer is adjacent to a second layer when the first layer is in direct contact with the second layer. In another example, a first layer is adjacent to a second layer when the first layer is separated from the second layer by a third layer.
The term “reaction space,” as used herein, generally refers to any environment suitable for depositing a material layer, film or thin film adjacent to a substrate, or the measurement of the physical characteristics of the material layer, film or thin film. A reaction space can include or be fluidically coupled to a material source. In an example, a reaction space includes a reaction chamber (also “chamber” herein). In another example, a reaction space includes a chamber in a system having a plurality chambers. A reaction space may include a chamber in a system having a plurality of fluidically separated chambers. A system for forming a photovoltaic cell can include multiple reactions spaces. Reactions spaces can be fluidically separated from one another. Some reaction spaces can be suitable for conducting measurements on a substrate or a layer, film or thin film formed adjacent to the substrate.
The term “fluid space,” as used herein, generally refers to any environment that can contain a fluid or direct a fluid along a fluid flow path. In some cases, a fluid space is a reaction space.
The term “flux,” as used herein, generally refers to the flow of a material. Flux in some cases is the flow rate of a material per unit area.
An aspect of the disclosure provides deposition systems for depositing a thin film photovoltaic cell on a flexible substrate. Such systems can be employed for use for forming photovoltaic cells comprising an absorber formed of copper indium gallium diselenide (CIGS), copper indium aluminum diselenide (CIAS), copper zinc tin disulfide/selenide (CZTS), copper indium diselenide (CIS), cadmium tellurium (“cadmium telluride”), or cadmium zinc tellurium.
A system for depositing a photovoltaic cell on a flexible substrate comprises an enclosure comprising a fluid space that is fluidically isolated from an environment external to the enclosure, and a plurality of deposition chambers in the fluid space. At least one deposition chamber of the plurality of deposition chambers comprises a magnetron sputtering assembly (or apparatus) (also “magnetron” herein) that directs a material flux of one or more target materials towards a portion of the flexible substrate that is disposed in the at least one deposition chamber of the plurality of deposition chambers. The system can further include at least one guide roller in the fluid space of enclosure. The guide roller can be configured to direct the flexible substrate to or from a given deposition chamber among the plurality of deposition chambers.
A deposition chamber can include one or more walls that contain a reaction space. The deposition chamber may have an opening for permitting a material flux to come in contact with the flexible substrate.
A guide roller can be disposed between a first deposition chamber and a second deposition chamber among the plurality of deposition chambers. The guide roller can be used to guide or otherwise direct the flexible substrate from the first deposition chamber to the second deposition chamber. The guide roller can be fluidically isolated from the first and second deposition chambers. The guide roller can be disposed in the fluid space.
A guide roller can direct or otherwise guide a flexible substrate from a substrate payout roller to a deposition chamber, from a deposition chamber to a substrate take-up roller, or from one deposition chamber to another deposition chamber among the plurality of deposition chambers. The payout roller can include a roll of a flexible substrate that is directed into one or more deposition chambers. The substrate can be wrapped (or wound) around a spool of the payout roller. Following film deposition, the substrate is directed into the take-up roller. The substrate can be directed into and wrapped (or wound) around a spool of the take-up roller.
A guide roller can be fluidically isolated from the first and second deposition chambers with the aid of a purge gas or other background gas that minimizes, or prevents, a gas or vapor from the deposition chambers from coming in contact with the roller.
The system can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100, or 1000 guide rollers. The system can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 100 guide rollers in between individual deposition chambers in the enclosure.
In some situations, the use of guide rollers can preclude the need for a drum to direct a flexible substrate among deposition chambers. This can advantageously aid in minimizing system complexity, which can aid in minimizing cost. In some examples, the system is drum less (i.e., not comprising a drum). In some implementations, the use of rollers (as opposed to a drum) can decouple (e.g., thermally decouple) deposition chambers (and portions or the substrate in each deposition chamber), which can enable various benefits and advantages. For example, the use of rollers as opposed to a drum can enable, for example, 1) simultaneous back side and front side coating of a substrate, which can provide for faster photovoltaic cell fabrication, 2) more rapid heating/cooling and higher heating rates, and 3) independent heating at various deposition chambers, which can provide for different temperatures and heating/cooling rates.
In some examples, the deposition chambers in the enclosure can be fluidically isolated from one another with the aid of a purge gas or other background gas that fills the enclosure. As an alternative, or in addition to, the enclosure can include a pumping system that pumps away a gas or vapor that flows from a deposition chamber into the fluid space.
The pumping system can include one or more vacuum pumps, such as one or more of a turbomolecular (“turbo”) pump, a diffusion pump, ion pump, cryogenic (“cryo”) pump, and a mechanical pump. A pump can include one or more backing pumps. For example, a turbo pump may be backed by a mechanical pump.
The system can further include a substrate payout roller (also “payout roller” herein) and a substrate take-up roller (also “take-up roller” herein) in the enclosure. During use, the flexible substrate is directed from the payout roller through each of the plurality of deposition chambers to the take-up roller.
The system can further include one or more additional deposition chambers that do not include magnetron sputtering assemblies (or apparatuses). The flexible substrate can be directed from the payout roller through the one or more additional deposition chambers to the take-up roller.
The enclosure can have various shapes and sizes. In some examples, the enclosure has a circular, triangular, square or rectangular cross-section. In an example, the enclosure is generally cylindrical in shape.
The enclosure can be formed of a metallic material, such as stainless steel. The enclosure can have a length from about 1 foot to 100 feet, or 1 foot to 10 feet, and a diameter (or width) from about 1 foot to 100 feet, or 1 foot to 10 feet. The enclosure can include a cap that seals the enclosure during system operation. The fluid space can be maintained at a given pressure with the aid of a pumping system in fluid communication with the fluid space.
For instance, the enclosure can be maintained under vacuum or in a controlled environment. The enclosure can be maintained under vacuum with the aid of a pumping system, as described elsewhere herein. In some situations, the enclosure is purged with a gas (e.g., Ar, He, Ne, N2).
In some example, the enclosure is maintained under vacuum with the aid of a pumping system. The enclosure can be maintained at a pressure that is less than or equal to about 100 torr, 1 torr, 10−1 torr, 10−2 torr, 10−3 torr, 10−4 torr, 10−5 torr, 10−6 torr, 10−7 torr, or 10−8 torr. As an alternative, the enclosure is maintained at a pressure that is elevated with respect to a pressure of an environment external to the enclosure. For example, the enclosure can be maintained at a pressure greater than or equal to about 10−6 torr, 10−5 torr, 10−4 torr, 10−3 torr, 10−2 torr, 10−1 torr, 1 torr, 100 torr, or 1000 torr.
The flexible substrate can be directed from one deposition chamber to another with the aid of a substrate web that supports the substrate. The substrate web can be configured to hold the substrate. In an example, the substrate web is a mesh.
The flexible substrate can be formed of various types of materials. In some cases, the flexible substrate is formed of an electrically conductive material. In an example, the flexible substrate is a stainless steel substrate. In another example, the flexible substrate is an aluminum substrate. In another example, the flexible substrate is formed of a polymeric material.
An individual chamber of the plurality of chambers of the system can include a first opening for permitting the flexible substrate to enter the individual chamber and a second opening for permitting the web to exit the individual chamber. The first and second openings are adapted to permit the flexible substrate to pass through the openings. The first and second openings can have various shapes and or sizes. In some examples, the openings are slits. The system can include a first roller adjacent to the first opening and a second roller adjacent to the second opening. The first roller is configured to direct the flexible substrate into the individual chamber and the second roller is configured to direct the flexible substrate out of the individual chamber.
The plurality of deposition chambers can include a plurality of magnetron sputtering assemblies. An individual magnetron sputtering assembly (or apparatus) can be disposed in an individual deposition chamber of the plurality of deposition chambers. In some cases, a deposition chamber includes a plurality of magnetron sputtering assemblies. For instance, a deposition chamber can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 100 magnetron sputtering assemblies, each of which can be configured to provide a flux of one or more target materials. A magnetron sputtering assembly can be a rotatable magnetron or a planar magnetron. A planar magnetron can have a horizontal configuration.
A system can include one or more deposition chambers. In some cases, a system comprising an enclosure housing at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 100 deposition chambers. The system can include a substrate payout roller for providing (e.g., feeding out) a substrate, and a substrate take-up roller for taking up the substrate following the deposition of one or more material layers in the deposition chambers of the system.
Photovoltaic cell layers can be deposited sequentially—i.e., one after the other. This can be accomplished by directing a portion of the substrate into deposition chambers sequentially.
The system in some cases includes at least one deposition chamber that comprises a plurality of magnetron sputtering assemblies. In some examples, the at least one deposition chamber includes a plurality of planar magnetron sputtering assemblies, a plurality of rotatable magnetron sputtering assemblies, or a combination of planar and rotatable magnetron sputtering assemblies.
In some examples, the system is configured for forming a silicon, CIGS, CIS, CIAS, CZTS, CdTe or CdZnTe absorber adjacent to the substrate. In such cases, a deposition chamber of the system can be configured to provide a material flux of copper, indium and gallium. The deposition chamber can provide a material flux of selenium, in some cases separately from the other material fluxes.
During use, the flexible substrate is directed into an individual deposition chamber and a portion of the flexible substrate that is in the deposition chamber is exposed to a material flux of one or more target materials. The flexible substrate can move through a deposition chamber at a continuous rate, such as at a rate of at least about 0.001 meters (m)/minute (min), 0.01 m/min, 0.1 m/min, 1 m/min, 10 m/min, or 100 m/min, or, as an alternative, in a series of steps.
One or more magnetron sputtering assemblies can be configured to provide a material flux from a liquid target. In some situations, at least one of the at least the subset of the plurality of deposition chambers of the system comprises a magnetron sputtering assembly comprising a rotatable magnetron sputtering apparatus adjacent to a planar magnetron sputtering apparatus, and one or more shields forming a sub-chamber between the rotatable magnetron sputtering apparatus and the planar magnetron sputtering apparatus. The planar magnetron sputtering apparatus can be configured to contain a liquid target having a first material and provide a material flux having the first material towards the rotatable magnetron sputtering apparatus. The rotatable magnetron sputtering apparatus can be configured to rotate a solid target having a second material in relation to the planar magnetron sputtering apparatus and provide a material flux having the first and second materials towards the flexible substrate. The first material can have a first melting point that is lower than a second melting point of the second material. In an example, the first material is gallium and the second material is indium. The planar magnetron sputtering apparatus can be configured to provide a flux of the first material in the sub-chamber.
In some cases, another planar magnetron sputtering apparatus can be provided adjacent to the planar magnetron sputtering apparatus. The other planar magnetron sputtering apparatus can be configured to provide a flux of a third material in the sub-chamber. The flux of the third material can be directed towards the rotatable magnetron sputtering apparatus.
The rotatable magnetron sputtering apparatus can be at least partly cylindrical in shape. In some cases, the rotatable magnetron sputtering apparatus is substantially cylindrical in shape. The planar magnetron sputtering apparatus can include a backing plate that is adjacent to a magnetron sputtering apparatus body. The magnetron sputtering apparatus body can include one or more magnets and the backing plate that is adapted to hold the liquid target.
In some cases, the rotatable magnetron sputtering apparatus can comprise a support member adapted to rotate the solid target in relation to the planar magnetron sputtering apparatus. The planar magnetron sputtering apparatus can be adapted to contain another liquid having a third material.
A deposition chamber can include multiple magnetron sputtering assemblies. In some cases, individual magnetron sputtering assemblies of a deposition chamber can be configured to provide a material flux towards the flexible substrate.
Magnetron sputtering assemblies can be situated in sub-chambers (i.e., chamber or enclosure within a deposition chamber) of deposition chambers. In an example, a magnetron sputtering assembly is enclosed in a sub-chamber having an opening adapted to expose the substrate to a material flux from the magnetron sputtering assembly.
A deposition chamber can include sources of other materials. Such source of other material may be magnetron sputtering assemblies or other types of deposition apparatuses. For instance, the system can include one or more additional deposition chambers that do not include magnetron sputtering apparatuses. In some cases, a source of a material is a vapor source that is provided into the deposition chamber through a fluid flow path that is in fluid communication with a liquid containing the material. In an example, selenium or sulfur vapor is provided into a deposition chamber through a fluid flow path that is in fluid communication with a liquid comprising selenium or sulfur.
Although a flexible substrate is used in the various examples and configurations provided herein, as an alternative, a non-flexible (e.g., glass slide) or substantially rigid substrate may be used. Payout and take-up rollers may be precluded in the case of a non-flexible substrate.
A system can include one or more deposition chambers in an enclosure (or chamber). In an example, an enclosure or all-encompassing chamber houses separate deposition chambers. The enclosure can be sealed from an environment external to the enclosure. An individual deposition chamber of the system can include one or more magnetron sputtering assemblies, each of which can be contained in a sub-chamber of the deposition chamber. In some cases, the system comprises an enclosure that is a chamber, and the enclosure houses separate deposition systems, which may be referred to as sub-chambers.
The system can include a deposition chamber comprising a magnetron sputtering apparatus that directs a material flux of one or more target materials to a back side of a flexible substrate. The system can include a deposition chamber comprising a first magnetron sputtering apparatus that directs a first material flux towards a front side of the flexible substrate, and a second magnetron sputtering apparatus that directs a second material flux towards a back side of the flexible substrate. The front side and back side can be opposite from one another.
For example, a deposition chamber among the plurality of deposition chambers of the system can include a first magnetron sputtering apparatus situated such that it faces a front side of a flexible substrate, and a second magnetron sputtering apparatus situated such that it faces a back side of the flexible substrate. The first magnetron sputtering apparatus can be configured to provide a material flux of target materials to form an absorber layer adjacent to the front side of a flexible substrate. The second magnetron sputtering apparatus can provide a material flux of a back electrode material (e.g., molybdenum, niobium, or tantalum) to the back side of the flexible substrate to form a back electrode adjacent to the flexible substrate.
As another example, the system can include a deposition system for depositing a thin film photovoltaic cell on a flexible substrate comprises an enclosure comprising a fluid space that is fluidically isolated from an environment external to the enclosure, and a plurality of deposition chambers in the fluid space. The plurality of deposition chambers comprises a first deposition chamber and a second deposition chamber. The first deposition chamber comprises a magnetron sputtering apparatus that directs a first material flux towards a first side of a portion of the flexible substrate. The second deposition chamber comprises a magnetron sputtering apparatus that directs a second material flux towards a second side of the portion that is opposite from the first side. A payout roller sequentially directs the flexible substrate through each of the plurality of deposition chambers to a take-up roller. The system can include one or more guide rollers for guiding or otherwise directing the flexible substrate to and through the deposition chambers.
In some cases, the first deposition chamber is disposed adjacent to the second deposition chamber. In an example, the first and second deposition chambers can be situated substantially adjacent one another such that the first material flux and second material flux are directed towards the first side and second side, respectively. In some cases, the first material flux and the second material flux are directed toward the first side and the second side at substantially the same time.
Another aspect of the present disclosure provides a method for forming a photovoltaic cell device structure adjacent to a flexible substrate. The method can comprise providing a deposition system comprising a plurality of deposition chambers in a sealed enclosure. The deposition system can be as described above or elsewhere herein. For example, the deposition system can include at least one deposition chamber that includes a magnetron sputtering apparatus that directs a material flux of one or more target materials towards a portion of the flexible substrate that is disposed in the at least one deposition chamber. The deposition system comprises a payout roller and a take-up roller in the enclosure. The payout roller provides the flexible substrate.
Next, the flexible substrate is directed from the payout roller through each of the plurality of deposition chambers in sequence to form the photovoltaic cell device structure adjacent to the flexible substrate. The flexible substrate can be directed through each of the plurality of deposition chambers upon the rotation of the payout and take-up rollers, which may be facilitated with the aid of one or more motors and regulated with the aid of a controller (see below). The flexible substrate is directed from the plurality of deposition chambers to the take-up roller.
In an example, the deposition system comprises six deposition chambers, a payout roller upstream of the deposition chambers, and a take-up roller downstream of the deposition chambers. The flexible substrate is directed from the payout roller through each individual deposition chamber in sequence, and from a last of the deposition chambers to the take-up roller, where the flexible substrate with photovoltaic device structure formed thereon is collected.
In some cases, the flexible substrate can be directed along at least one roller that is disposed between a first deposition chamber and a second deposition chamber of the plurality of deposition chambers. The flexible substrate can be directed along at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, or 100 rollers.
A photovoltaic manufacturing system can include multiple systems. Each system can be as described above or elsewhere herein. A given system can be dedicated for use in forming a given PV device structure (e.g., absorber). During use, a user may provide a payout roller comprising a flexible substrate in a first system, process the flexible substrate to include a given device structure and collect the flexible substrate on the take-up roller, remove the take-up roller from the first system, and install the take-up roller as a payout roller of a second system for further PV processing.
A PV manufacturing system can include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, or 50 separate systems, each comprising an enclosure that comprises a plurality of deposition chambers, as described elsewhere herein.
Reference will now be made to the figures, wherein like numerals refer to like parts throughout. It will be appreciated that the figures (and features therein) are not necessarily drawn to scale.
An overall three dimensional perspective view of a deposition system (or machine) is shown in
A photovoltaic manufacturing system can include multiple systems, such as that illustrated in
Still referring to
The arrangement of rollers 9 in
With reference to
Sputtering gas (e.g., argon) and reactive gases are introduced into the chamber through two long tubes 16 which have an array of small holes all along their length. The gases flow around rotatable magnetrons 10 as suggested by the arrows. The gases are made to travel near the surface of the magnetrons by flow restrictors 17 at each side and 18 in the middle between the magnetrons. The restrictors may be made from aluminum, but they need not be solid in cross section. When sputtering using direct current (DC) power, they may conveniently do double duty by becoming the electrical anode for the plasma which is produced by magnetrons 10.
Rotatable magnetrons may be purchased from a number of commercial vendors, but they all share some common basic features. For instance magnetron 10 has a target material 10a, a backing tube 10b that holds the target material, and a magnetic array 10c for producing magnetic fields 19. The backing tube may be eliminated for target materials that have sufficient strength to be made in monolithic tubular form. The magnetic fields trap electrons in the plasma which allows the plasma to be maintained at low sputtering pressures. The magnetic array can be oriented at a convenient angle θ with respect to the substrate. The rotatable magnetrons may also include various improvements in structure and operation of the magnetic array which provides increased target utilization. An example improvement is fully described in U.S. patent application Ser. No. 12/753,814 and Patent Cooperation Treaty (PCT) Patent Application No. PCT/US2011/030793, each of which is entirely incorporated herein by reference.
With continued reference to
As mentioned above,
With reference to
Still with reference to
A third chamber configuration shown in
Several examples of chamber configurations for both the drum (stations I, II, and III) and free span (stations IV, V, and VI) versions of the machine architecture are illustrated in
Systems and methods of the disclosure can be implemented with the aid of computer systems. A system can include an enclosure comprising one or more deposition systems, and a pumping system. A computer system (or controller) can be coupled to the system. The computer system can include a computer processor (also “processor” herein) for executing machine readable code implementing a method for forming a photovoltaic cell. The code may implement any of the methods provided herein.
A controller can be coupled to various components of the system. For instance, the controller can be in communication with the one or more deposition systems, including magnetron sputtering apparatuses of the one or more deposition systems. As another example, the controller can be in communication with the pumping system, which can enable the controller to regulate a pressure of the enclosure.
A controller can be programmed or otherwise configured to regulate one or more processing parameters, such as the substrate temperature, precursor flow rates, growth rate, carrier gas flow rate, deposition chamber pressure and magnetron power. The controller, in some cases, is in communication with a valve or a plurality of valves of a deposition chamber, which aids in terminating (or regulating) the flow of a precursor in the deposition chamber. The controller includes a processor configured to aid in executing machine-executable code that is configured to implement the methods provided herein. The machine-executable code is stored on a physical storage medium, such as flash memory, a hard disk, or other physical storage medium configured to store computer-executable code.
A controller can be programmed or otherwise configured to regulate one or more processing parameters. In some situations, the controller regulates one or more of the growth temperature, carrier gas flow rate, precursor flow rate, photovoltaic material layer growth rate and growth pressure. Growth rate can be regulated, for example, by controlling the rate at which a portion of a substrate is directed through a deposition chamber, which can be dependent on the rate at which the substrate payout and update rolls (e.g., rolls 5 and 6 of
For instance, the system of
The computer system 1401 is in communication with a processing system 1435 for forming one or more components (e.g., absorber, back electrode, front electrode) of photovoltaic cells of the disclosure. The processing system 1435 can be configured to implement various operations to form one or more PV cell component structures adjacent to a substrate in the processing system 1435, such as, for example, forming one or more absorber layers. The processing system 1435 can be in communication with the computer system 1401 through the network 1430, or by direct (e.g., wired, wireless) connection. In an example, the processing system 1435 is the system described above in the context of
Methods as described herein can be implemented by way of machine (or computer processor) executable code (or software) stored on an electronic storage location of the computer system 1401, such as, for example, on the memory 1410 or electronic storage unit 1415. During use, the code can be executed by the processor 1405. In some examples, the code can be retrieved from the storage unit 1415 and stored on the memory 1410 for ready access by the processor 1405. In some situations, the electronic storage unit 1415 can be precluded, and machine-executable instructions are stored on memory 1410.
The code can be pre-compiled and configured for use with a machine have a processor adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a pre-compiled or as-compiled fashion.
Aspects of the systems and methods provided herein can be embodied in programming. Various aspects of the technology may be thought of as “products” or “articles of manufacture” typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. “Storage” type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible “storage” media, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution.
Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.
A machine configuration for coating the back electrode layer for a CIGS solar cell on a web of thin stainless steel (SS) foil is shown in
Some substrates might be improved by an in vacuum surface treatment. One such treatment can be a sputter etching of the foil surface to remove foreign material, reduce topology, or remove a thin layer of oxide buildup.
Referring still to
CIGS solar cells may benefit from the addition of a small amount of sodium, of the order of 0.1%. In some cases, a small amount of sodium can be provided in the form of atomic sodium or a compound comprising sodium (e.g., NaF, NaSe, NaS, etc.) in one or more of the CIGS targets, for ultimate deposition in a growing CIGS absorber adjacent to a substrate. However, it can also be included in the molybdenum back electrode where it can diffuse into the CIGS. Another alternative is to deposit a sodium compound layer by sputtering from a planar magnetron(s) housed in a chamber 37 shown in
The highest efficiency CIGS solar cells produced in the laboratory have used chemical bath deposition of cadmium sulfide (CdS) as a junction layer; however, commercial CIGS modules have also used cells with chemically deposited junction layers of zinc sulfide (ZnS) and indium sulfide (In2S3). It is possible to produce the junction layer by sputtering, and
Unlike conventional silicon solar cells, thin film cells need a transparent top electrode which is almost always deposited by sputtering. Indium tin oxide (ITO) and zinc oxide slightly doped with aluminum (AZO) are two materials that can be used for this purpose. Both can be provided in rotatable format, and both are sufficiently conductive to sputter by direct current (DC), pulsed DC, or AC power.
Suppliers may not be able to provide stainless steel foil substrates as smooth and as devoid of surface defects as glass. As a result, thin film solar cells made on flexible stainless steel webs can have large numbers of electrical defects that can be employed in a manufacturing environment. Transport rollers in a web coating machine that touch the coating side of the web can induce a number of defects due to sliding and scratching, or by simply mashing particles into the coating.
In some cases, it may be permissible to have a roller contact with the coated side of the web after a coating is applied—for example, after the final top transparent electrode is deposited.
Devices, systems and methods of the disclosure may be combined with or modified by other devices, systems and methods, such as devices, systems and/or methods described in U.S. Pat. No. 8,207,012 to Pinarbasi et al., U.S. Pat. No. 4,318,938 to Barnett et al., U.S. Pat. No. 6,974,976 to Hollars, U.S. Pat. No. 5,571,749 to Matsuda et al., U.S. Pat. Nos. 6,310,281 and 6,372,538 to Wendt et al., U.S. Pat. No. 4,298,444 to Chahroudi, U.S. Patent Publication No. 2010/0140078 to Pinarbasi et al., and U.S. Patent Publication No. 2012/0006398 to Nguyen et al., each of which is entirely incorporated herein by reference.
Unless the context clearly requires otherwise, throughout the description and the claims, words using the singular or plural number also include the plural or singular number respectively. Additionally, the words ‘herein,’ ‘hereunder,’ ‘above,’ ‘below,’ and words of similar import refer to this application as a whole and not to any particular portions of this application. When the word ‘or’ is used in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list and any combination of the items in the list.
It should be understood from the foregoing that, while particular implementations have been illustrated and described, various modifications may be made thereto and are contemplated herein. An embodiment of one aspect of the disclosure may be combined with or modified by an embodiment of another aspect of the disclosure. It is not intended that the invention(s) be limited by the specific examples provided within the specification. While the invention(s) has (or have) been described with reference to the aforementioned specification, the descriptions and illustrations of embodiments of the invention(s) herein are not meant to be construed in a limiting sense. Furthermore, it shall be understood that all aspects of the invention(s) are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. Various modifications in form and detail of the embodiments of the invention(s) will be apparent to a person skilled in the art. It is therefore contemplated that the invention(s) shall also cover any such modifications, variations and equivalents.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/587,994, filed Jan. 18, 2012, which application is entirely incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2013/022284 | 1/18/2013 | WO | 00 | 7/10/2014 |
| Number | Date | Country | |
|---|---|---|---|
| 61587994 | Jan 2012 | US |
