Patent Application
20100180927
NOT APPLICABLE
NOT APPLICABLE
The present invention relates generally to photovoltaic materials and manufacturing methods. More particularly, the present invention provides a conformal solar decal device and method using high efficiency thin film photovoltaic cells. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.
From the beginning of time, mankind has been challenged to find ways of harnessing energy. Energy comes in forms such as petrochemical, hydroelectric, nuclear, wind, biomass, solar, and more primitive forms such as wood and coal. Over the past century, modern civilization has relied upon petrochemical energy as an important energy source. Petrochemical energy includes gas and oil. Gas includes lighter forms such as butane and propane, commonly used to heat homes and serve as fuel for cooking Gas also includes gasoline, diesel, and jet fuel, commonly used for transportation purposes. Heavier forms of petrochemicals can also be used to heat homes in some places. Unfortunately, the supply of petrochemical fuel is limited and essentially fixed based upon the amount available on the planet Earth. Additionally, as more people use petroleum products in growing amounts, it is rapidly becoming a scarce resource, which will eventually become depleted over time.
More recently, environmentally clean and renewable source energy has been desired. An example of a clean source of energy is hydroelectric power. Hydroelectric power is derived from electric generators driven by the flow of water produced by dams such as the Hoover Dam in Nevada. The electric power generated is used to power a large portion of the city of Los Angeles in California. Clean and renewable sources of energy also include wind, waves, biomass, and the like. That is, windmills convert wind energy into more useful forms of energy such as electricity. Still other types of clean energy include solar energy. Specific details of solar energy can be found throughout the present background and more particularly below.
Solar energy technology generally converts electromagnetic radiation from the sun to other useful forms of energy. These other forms of energy include thermal energy and electrical power. For electrical power applications, solar cells are often used. Although solar energy is environmentally clean and has been successful to a point, many limitations remain to be resolved before it becomes widely used throughout the world. As an example, one type of solar cell uses crystalline materials, which are derived from semiconductor material ingots. These crystalline materials can be used to fabricate optoelectronic devices that include photovoltaic and photodiode devices that convert electromagnetic radiation to electrical power. However, crystalline materials are often costly and difficult to make on a large scale. Additionally, devices made from such crystalline materials often have low energy conversion efficiencies. Other types of solar cells use “thin film” technology to form a thin film of photosensitive material to be used to convert electromagnetic radiation into electrical power. Similar limitations exist with the use of thin film technology in making solar cells. That is, efficiencies are often poor. Additionally, film reliability is often poor and cannot be used for extensive periods of time in conventional environmental applications. Often, thin films are difficult to mechanically integrate with each other. These and other limitations of these conventional technologies can be found throughout the present specification and more particularly below.
From the above, it is send that improved techniques for manufacturing photovoltaic materials and resulting devices are desired.
According to the present invention, techniques generally related to photovoltaic materials and manufacturing methods are provided. More particularly, the present invention provides a conformal solar decal device and method using high efficiency thin film photovoltaic cells. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.
In a specific embodiment, the present invention provides a solar device. The solar device includes a substrate structure having a surface region and a flexible and conformal material comprising a polymer material affixing the surface region. Additionally, the solar device includes one or more solar cells spatially provided by one or more films of materials characterized by a thickness dimension of 25 microns and less and mechanically coupled to the flexible and conformal material. The one or more solar cells have a flexible characteristic that maintains each of the solar cells substantially free from any damage or breakage. Moreover, the solar device includes an interconnect structure configured to couple one or more of the solar cells. The interconnect structure includes at least a first contact region and a second contact region within the flexible and conformal material.
In another specific embodiment, the present invention provides a solar decal device affixable to a substrate structure. The solar decal device includes a flexible and conformal material comprising a polymer material capable of detachment from a surface region of a transparent handle substrate. Additionally, the solar decal device includes an interface region provided within a vicinity between the surface region and the flexible and conformal material. The solar decal device further includes one or more films of materials coupled to the flexible and conformal material. The one or more films of materials includes an absorber material having a grain size ranging from about 0.5 to about 4 microns. Furthermore, the solar decal device includes one or more solar cells spatially provided by one or more films of materials characterized by a thickness dimension of 25 microns and less and mechanically coupled to the flexible and conformal material. The one or more solar cells have a flexible characteristic that maintains each of the solar cells substantially free from any damage or breakage thereto when the one or more films of materials is subjected to bending. Moreover, the solar decal device includes an interconnect structure configured to couple one or more of the solar cells. The interconnect structure includes at least a first contact region and a second contact region within the flexible and conformal material.
In an alternative embodiment, the present invention provides a method for manufacturing a solar decal device affixable to a substrate structure. The method includes providing a transparent substrate member having a surface region and forming a flexible and conformal material overlying the surface region with a polymer material capable of detachment from the transparent substrate member. Additionally, the method includes patterning the flexible and conformal material to form one or more exposed regions for an interconnect structure and filling the exposed regions with one or more conductive materials. The method further includes forming an interface region within a vicinity between the surface region of the transparent substrate member and the polymer material and forming one or more films of materials with a thickness dimension of 25 microns and less mechanically overlying the flexible and conformal material and coupled to at least the interconnect structure. Furthermore, the method includes forming one or more solar cells spatially provided by the one or more films of materials with a flexible characteristic. The flexible characteristic maintains each of the solar cells substantially free from any damage or breakage thereto when the one or more films of materials is subjected to bending. The method further includes supporting at least the transparent substrate member, the flexible and conformal material, the interface region, and the one or more solar cells to expose a backside region of the transparent substrate member. Moreover, the method includes irradiating the backside region with electromagnetic radiation to selectively release the flexible and conformal material from the surface region of the transparent substrate member to substantially free the one or more solar cells spatially provided by the one or more films of materials mechanically coupled to the flexible and conformal material.
Many benefits are achieved by way of the present invention. For example, the present invention uses starting materials that are commercially available to form a thin film of semiconductor bearing material overlying a suitable substrate member. The thin film of semiconductor bearing material can be further processed to form a semiconductor thin film material of desired characteristics, such as atomic stoichiometry, impurity concentration, carrier concentration, doping, and others. Additionally, the present method uses environmentally friendly materials that are relatively less toxic than other thin-film photovoltaic materials. Depending on the embodiment, one or more of the benefits can be achieved. In a preferred embodiment, the present method uses a conformal and flexible carrier material having an overlying photovoltaic material thereon, which can be applied overlying almost any object of shape and size with a “glove-like” fit. These and other benefits will be described in more detail throughout the present specification and particularly below. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.
According to the present invention, techniques generally related to photovoltaic materials and manufacturing methods are provided. More particularly, the present invention provides a conformal solar decal device and method using high efficiency thin film photovoltaic cells. Merely by way of example, the present method and materials include absorber materials made of copper indium disulfide species, copper tin sulfide, iron disulfide, or others for single junction cells or multi junction cells.
Referring to
The coating of the flexible and conformal material 110 can be performed using extrusion, painting, doctor-blade, spin-on, thermal reflow, spray, dipping, electrostatic bonding, and any combination of these techniques and others. In one embodiment, a first layer of the polyimide material is applied directly onto the surface region 111. Subsequently (may adjusting some processing conditions such as temperature, thickness, density, and curing time, etc), a second layer of the polyimide material is applied. In some case, the second layer of the polymer material may be different from the polyimide material used for the first layer. As a result, the first layer, which is correspondingly next to the surface region, is subjecting to a predetermined releasing process. In particular, the technique results a formation of an interface region between the flexible and conformal material 110 and the surface region 111. Depending on the embodiments, the composition of the first layer polymer can be engineered for best releasing performance for either a chemical release mechanism, a photo-reactive release mechanism, or a thermal release mechanism, a photo-plus-thermal release mechanism using laser irradiation from the backside of the transparent substrate member. In an alternative embodiment, this coating technique is also advantageously applied when coating the polymer material over one application substrate member which is for affixing the detached solar cell. More details on this coating process will be described later. Of course, there coating can also be applied as a tape (e.g., polymer film) or other substrate material.
In one implementation, the interconnect structure 112 includes at least a first contact region 112A and a second contact region 112B formed within the flexible and conformal material 110. For example, after coating the flexible and conformal material 110 onto the surface region 111 of the substrate 101, the flexible and conformal material 110 (which can be selected from a polymer material) is patterned to form one or more vias and then filled with one of conductive materials. In one specific embodiment, the first contact region 112A is directly embedded in the flexible and conformal material 110 with a partial exposed portion. The second contact region 112B can be also embedded within the flexible and conformal material 110 but is surrounded by an insulating material 113 which may be further extended above the flexible and conformal material 110.
In a specific embodiment, one or more films of materials 120 include a first electrode layer 121 and a second electrode layer 125 to cap the light absorber layer 122 and the window layer 124. Both the first electrode layer 121 and the second electrode layer 125 are made of conductive material characterized by a resistivity less than about 10 ohm-cm. The conductive material can be selected from gold, silver, nickel, platinum, aluminum, tungsten, molybdenum, a combination of these, or an alloy, among others. For example, the conductive material may be deposited using techniques such as sputtering, electroplating, electrochemical deposition and others. In other examples, the first electrode layer 121 and the second electrode layer 125 can be made of an alternative conducting material such as a carbon-based material such as carbon or graphite, or a combination of different conductive materials. Yet alternatively, the first electrode layer 121 and the second electrode layer 125 may be made of a conductive polymer material, an optically transparent material or materials that are light reflecting or light blocking depending on the application. Examples of the optically transparent material can include indium tin oxide (ITO), aluminum doped zinc oxide, fluorine doped tin oxide and others. Of course there can be other variations, modifications, and alternatives.
Referring to the
Shown in
Additionally, the window layer 124 is made of a semiconductor material with N+ impurity type characteristics. A P-N junction is formed between the N+ window layer 124 and the P type absorber layer 122. In a specific implementation, the window layer 124 is characterized by a semiconductor bandgap greater than about 2.5 eV, for example, ranging from 2.5 eV to about 5.5 eV. In a specific embodiment, the window layer 124 comprises a metal chalcogenide semiconductor material and/or other suitable semiconductor material, including a metal sulfide, or a metal oxide, or a metal telluride or a metal selenide material. Alternatively, the window layer 124 can include a metal silicide depending on the application. In another specific embodiment, the window layer 124 can be deposited using techniques such as sputtering, spin coating, doctor blading, powder coating, electrochemical deposition, inkjeting, among others, depending on the application. Of course, there can be other variations, modifications, and alternatives.
In certain embodiments, one or more additional P-N junctions, each including an N+ type window layer substantially similar to the window layer 124 overlying a P type absorb layer substantially similar to the absorber layer 122, can be formed over the P-N junction mentioned earlier. In particular, the film compositional structure and electrical-optical characteristics for each P-N junction can be substantially similar. Alternatively, different P-N junction can have different types of photovoltaic materials. The one or more P-N junctions can be coupled to each other via a coupling layer (not explicitly shown). In one embodiment, the coupling layer can be a conductive material, serving as an electrical middle terminal of one or more solar cells. It also serves as a mechanical bonding material between each pair of P-N junctions. In one embodiment, the coupling layer is a multi-layer film, including a glue layer sandwiched between two conductive electrode layers. One conductive electrode layer below is configured to be the upper electric terminal for a first P-N junction and another conductive electrode layer on top serves a lower electric terminal for the second P-N junction over the first P-N junction. Of course there can be other variations, modifications, and alternatives.
Finally referring to the
In one implementation shown in
Also shown in
In order to properly affix the solar decal device 500 onto the surface 601, a layer of flexible and conformal material 610 is applied first. In one embodiment, the layer of flexible and conformal material 610 comprises a polyimide material having a thickness of about 20 microns. The polyimide material has a predetermined fluidic characteristics that can overlays the whole surface 601 in conformal fashion. For example, a spatial feature as large as desirable in the surface 601 can be covered. As a result, a polymer surface 611 becomes much smoother than original substrate surface 601. In another embodiment, the coated flexible and conformal material 610 is configured to bond with the carrier material 110′ associated with the solar decal device 500.
1. Process 710 for providing an optical transparent substrate having a surface region and a backside region;
2. Process 715 for forming a flexible and conformal material overlying the surface region;
3. Process 720 for forming an interface region;
4. Process 725 for patterning the flexible and conformal material to form one or more exposed regions for an interconnect structure;
5. Process 730 for filling the one or more exposed regions with conductive materials;
6. Process 735 for forming one or more films of materials overlying the flexible and conformal material;
7. Process 740 for forming one or more solar cells provided by the one or more films of materials;
8. Process 745 for supporting optically transparent substrate, the flexible and conformal material, interface region, and the one or more solar cells;
9. Process 750 for irradiating the backside region with electromagnetic radiation;
10. Process 755 for freeing the one or more solar cells to form a solar decal device; and
11. Process 760 for affixing the solar decal device to a substrate.
The above sequence of processes provides a method for manufacturing a solar decal device affixable to a substrate structure according to an embodiment of the present invention. Other alternatives can also be provided where some processes are added, one or more processes can be removed, or one or more processes are provided in a different sequence without departing from the scope of the claims herein. Further details of the method can be found throughout the present specification and more particularly below.
At Process 710, an optically transparent substrate is provided. In one embodiment, the optically transparent substrate includes a substrate material selected from a dielectric material, such as glass or quartz, a polymer or plastic material, a metal material, a semiconductor, a composite, or layered material, and the like. In another embodiment, the optically transparent substrate is transparent to an electromagnetic radiation with a predetermined wavelength range. For example, the electromagnetic radiation is a laser beam with wavelength ranging from 400 nm to 700 nm, but can be others. In one implementation, the optically transparent substrate includes a surface region and a backside region, which is substantially the same as the handle substrate 101 shown in
At Process 715, a flexible and conformal material is formed overlying the optically transparent substrate. In one embodiment, the flexible and conformal material is a polymer material with a thickness ranging from 1 micron to 10 microns. In a specific embodiment, the flexible and conformal material is a polyimide material. In one implementation,
At Process 720, an interface region is formed between the flexible and conformal material and the surface region of the transparent substrate. In particular, the interface region is referred to a spatial area with hetero-molecular interactions between two different types of materials. Unlike inside region within the polymer material or inside region within the substrate material where homo-molecular interaction is dominated by strong covalence bond or hydrogen bond, the interface region between the polymer material and the substrate material is characterized by relatively weak Van der Wal's forces specifically between the molecules of the polymer material and molecules of the substrate material. During the application process, the polymer material of the flexible and conformal material forms a plurality of Van der Wal's forces that are just strong enough to hold onto the transparent substrate and serve as a new base for forming a thin film solar cell. More importantly, this interface region advantageously facilitates a detachment process performed later for forming a solar decal device.
At Process 725, the flexible and conformal material is patterned to form one or more exposed regions for an interconnect structure. In one implementation, the one or more exposed regions includes one or more vias. Depending on the application, at least a first via has a proper position, depth, width, and length. At least a second via also is formed in the Process 725 with a position separated from the first via. This process can be performed using photo-processing, masking, etching, or others. In one embodiment, the Process 715 and the Process 725 may have different orders when executing one or more steps. For example, an etching process may be followed by another polymer deposition process or vise versa.
At Process 730, the method 700 includes filling the one or more exposed regions with a conductive material. In particular, this process is to introduce actual material into the patterned vias to form the actual interconnect structure. The conductive material can be selected from aluminum, copper, nickel, Alloy 42, silver, gold, molybdenum, or other metal or a conductive dielectric material which is deposited specifically to fill the vias. In one implementation, at least the first via is filled to form a first contact region. The first contact region has at least a portion of area that is exposed as part of an surface area of the flexible and conformal material, intending for directly coupling with an electrode layer overlying said surface area. In addition, the second via can be filled with the conductive material to form a second contact region. In one implementation, the second contact region is also embedded within the flexible and conformal material but with an extension structure above the surface area, intending for coupling with another electrode layer. Specifically, the second contact region may be covered or surrounded by an insulating material to prevent it from electrically shorting the second contact region with other layer structures.
At Process 735, one or more films of materials are formed overlying the flexible and conformal material. In particular, the one or more films of materials are thin film photovoltaic materials configured to form one or more P-N junctions between at least two conducting electrode layers. For example, the one or more films of materials includes a first electrode layer overlying the flexible and conformal material. The first electrode layer also makes a direct coupling with the first contact region formed in Process 730. Over the first electrode layer an absorber layer is formed and followed by a window layer to have a P-N junction. Above that, a second electrode layer is formed overlying the window layer. The second electrode layer is configured to make electrical coupling with the second contact region formed at Process 730. In an embodiment, the Process 725, 730 and 735 may be executed in different orders when performing some steps. For example, forming the absorber layer and window layer may be before forming the insulation material for the second contact region or vise versa. In one specific implementation, the one or more films of materials are the films 120 including the first electrode layer 121, the absorber layer 122, the window layer 124, the second electrode layer 125, and the first contact region as well as the second contact region forming the interconnect structure 112, according to the illustration of
At Process 740, one or more solar cells are formed from the one or more films of materials. In one embodiment, the one or more films of materials overlying the flexible and conformal material are separated into one or more units using a laser separation technique developed by the inventor. In another embodiment, the one or more solar cells are characterized by a thin film with a thickness dimension of 25 microns and less. More details about the laser separation processes for forming a plurality of unit cells can be found in a U.S. Patent Application No. 61/033,406, titled “LASER SEPARATION METHOD FOR MANUFACTURE OF UNIT CELLS FOR THIN FILM PHOTOVOLTAIC MATERIALS” and commonly assigned, and hereby incorporated by reference herein. In one implementation, each unit cell is formed in a stripe shape on a portion of the surface region of the transparent substrate. Each unit cell includes a solar cell overlying a portion of flexible and conformal material.
At Process 745, the method 700 includes supporting the optically transparent substrate, flexible and conformal material, interface region, and the one or more solar cells as a whole work piece. In particular, the process includes disposing the whole work piece at a process station where the optically transparent substrate is properly supported so that the backside region is fully exposed to a laser source. The laser source is selected with predetermined pulse rate, wavelength, power range, and beam characteristic that accommodate the optically transparent substrate and capable of interacting with the polymer material at the interface region between the flexible and conformal material and the surface region.
At Process 750, the method 700 further includes irradiating the backside region with an electromagnetic radiation. In specific implementation, the electromagnetic radiation is a laser beam generated by the laser source within the process station. The laser beam is scanned from a portion of the backside region to another portion and transmitted through the optically transparent substrate to reach the interface region. In certain embodiment, the laser beam is a pulsed laser in nature. In other embodiment, the laser beam can be CW laser.
At Process 755, the one or more solar cells are freed from the surface region of the transparent substrate. As the laser energy is absorbed by the molecules within the interface region, the relatively weak Van der Wal's bonds between hetero-molecules at the interface region are substantially broken so that the polymer material becomes detachable. As the laser power and exposure time is properly selected, the film structure and associated device functionality of the one or more solar cells provided by the one or more films of materials above the flexible and conformal material are still substantially free of any damages. In a specific embodiment, for the one or more solar cells have been pre-formatted into stripe shapes, the one or more solar cells can be peeled off one-by-one in stripe shape from one portion of the surface region to another portion. As each solar cell is released from the optically transparent substrate, a portion of flexible and conformal material is still tightly attached, serving as a carrier material to hold the thin film solar cell. In one implementation, the transferred solar cells carried by the remaining portion of flexible and conformal material becomes a solar decal device that is also flexible to some degrees. The flexible solar decal device can be shipped stand-alone and capable of affixing to a variety of application substrate. The flexible characteristic is represented by bending the whole device to a certain radius of curvature which causes substantially free damages or breakage of the solar cells thereto.
At Process 760, the method 700 includes affixing the solar decal device to an application substrate structure. In particular, the application substrate structure is pre-coated with a matching polymer material that is flexible and conformal to corresponding surface features with certain aspect ratio. In one embodiment, the aspect ratio can be as large as desired. In certain implementation, the size of the spatial features on the application substrate structure can be four times larger than the thickness of the thin film solar cell to be affixed. In another embodiment, certain thermal process or chemical process is performed to ensure the bonding between the remaining flexible and conformal material associated with the solar decal device and the matching polymer material. Finally, the solar decal device is affixed with the application substrate, mediated with a flexible and conformal material in between so that the solar cells can be attached to surfaces of the application substrate structure which might be rough to some degrees. For example, the application substrate structure includes a portion of a cell phone, a blue tooth device, a laptop, a personal digital assistant, a wireless device, a sensor device, a camera device, a windshield, a window or other surfaces. In another aspect, the application substrate surface can be a portion of an automobile, glass, window, laptop computer, handheld PDA device, clothing, table, housing tile, outdoor furniture, and other shaped or planar objects, including any of those noted herein, and outside of this specification.
Although the above has been described in terms of specific embodiments, one of ordinary skill in the art would recognize other variations, modifications, and alternatives. As an example, a cell can be made of cadmium telluride (CdTe) material that is a crystalline compound formed from cadmium and tellurium. In a specific embodiment, the CdTe has a zinc blend (cubic) crystal structure. As an example, the CdTe crystalline form is a direct bandgap semiconductor. Depending upon the embodiment, the CdTe is sandwiched with cadmium sulfide to form a P-N junction photovoltaic solar cell. In a specific embodiment, a multi junction cell including an upper cell and lower cell. As an example, the upper cell or any cell can made according to HIGH EFFICIENCY PHOTOVOLTAIC CELL AND MANUFACTURING METHOD listed under U.S. Patent Application No. 61/059,253 (Attorney Docket No. 026335-002500US), commonly assigned, and hereby incorporated for all purposes. In one or more embodiments, the top cell comprises an absorber layer selected from CuInS2, SnS, Cu(In2Al)S2, Cu(In1-x), Alx)S2, Cu(In, Ga)S2, or Cu(In1-x, Ga)S2 or other suitable materials. In other specific embodiments, the bottom cell may comprise an absorber layer selected from CIGS, Cu2SnS3, FeS2, or Ge or others. Additionally, the lower cell can be made of an alternative material that receives any traversing energy through the upper cell. As an example, the lower cell can be made of a suitable material such as silicon, polysilicon, CIGS, and other materials. Of course, there can be other variations, modifications, and alternatives.
It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/092,371, filed Aug. 27, 2008, entitled “AFFIXING METHOD AND SOLAR DECAL DEVICE USING A THIN FILM PHOTOVOLTAIC AND INTERCONNECT STRUCTURES” by inventor CHESTER A. FARRIS III commonly assigned and incorporated by reference herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 61092371 | Aug 2008 | US |
