Front electrode for use in photovoltaic device and method of making same

Front Electrode for Use in Photovoltaic Device and Method of Making Same

Background of the invention

This invention relates to a photovoltaic device comprising an electrode such as a front electrode/contact. In some representative embodiments, the front electrode of the photovoltaic device includes a multilayer coating material comprising at least one substantially infrared (IR) reflective and conductive metal layer made of or including silver, gold, or the like, and of The packaging material may include at least one permeable conductive oxide (TCO) layer (e.g., made of or comprising tin oxide, zinc oxide, or the like). In some representative embodiments, the multilayer front electrode coating material is designed to achieve one or more of the following characteristic properties: (a) Reduced plate resistance (Rs) hence increased conductivity and improved overall output power of a PV module; (b) Increase infrared (IR) reflectance and thus reduce the operating temperature of the photovoltaic module in order to increase the output power of the module; (c) Reduce reflection and/or increase light transmission in the region of 450-700 nm, and/or 450-600 nm, which results in increased output power of the photovoltaic module; (d) Reducing the overall thickness of the front electrode sheathing material, enabling Reducing manufacturing costs and/or time; And/or (e) improving or expanding the processing window when forming the TCO layer(s) due to the reduced effect of the conductivity of the TCO layers on the overall electrical properties of the module given the presence of a mainly metallic layer(s) that reflects infrared (IR) radiation. Highly conductive.

Photovoltaic devices are well known in the art (for example, see U.S. Patents Nos. 6,784,361, 6,288,325, 6,613,603, and 6,123,824, the disclosures of which are incorporated herein by reference). Photovoltaic devices made of amorphous silicon, for example, include a front electrode or contact. Typically, the conducting front electrode is made of a conductive thermal oxide (TCO) such as zinc oxide or tin oxide formed on a substrate such as a glass substrate. In many cases, the single-layer conducting front electrode is formed using a pyrochemical method in which pyrolysis-producing raw materials are sprayed onto the glass substrate at about 400 to 600°C. Typical TCO layers of fluorine-doped tin oxide that are thermally decomposed and used as front electrodes can be about 400 nm thick, providing a plate resistance (Rs) of about 15 ohms/square. To obtain a large output power, it is desirable to have a front electrode that has low plate resistance and good ohmic contact with the top layer of the cell, allowing maximum solar energy in certain desirable ranges to penetrate the absorbing semiconductor films.

Unfortunately, photovoltaic devices (e.g., solar cells) incorporating conventional TCO front electrodes suffer from the following problems.

First, a pyrolytic fluoro-doped tin oxide TCO layer about 400 nm thick used as the full front electrode has a sheet resistance (Rs) of about 15 ohms/square which is large for a full front electrode. It is desirable to have a lower plate resistance (and thus better conductivity) for the front electrode of a photovoltaic device. A lower plate resistance can be achieved by increasing the thickness of such a TCO layer, but this will cause reduced light transmission through the TCO layer, reducing the output power of the photovoltaic device.

Second, conventional TCO front electrodes such as pyrolytic tin oxide allow a fairly large amount of infrared (IR) radiation to pass through it, allowing it to reach the semiconductor or absorbing layer(s) of the photovoltaic device. These infrared rays cause heat that increases the operating temperature of the photovoltaic device and thus reduces its output power.

Third, conventional TCO front electrodes such as pyrolytic tin oxide tend to reflect a fairly large amount of light in the region of about 450–700 nm so that at least about 80% of the useful solar energy reaches the absorbing semiconductor layer; This rather high reflection of visible light is a waste of energy and results in reduced output power of the photovoltaic module. Because of the absorption of the TCO layer and the reflections of light that occur between the TCO layer (n about 1.8 to 2 at a wavelength of 550 nm) and the thin semiconductor film (n about 3 to 4), and between the TCO layer and the glass substrate (n about 1.5), The TCO-coated glass at the front of a photovoltaic device typically allows less than 80% of the useful solar energy that hits the device to reach the semiconductor film that converts the light into electrical energy.

Fourth, the large total thickness (e.g., 400 nm) of the front electrode in the case of a 400 nm TCO layer causes increased manufacturing costs.

Fifth, the processing window for forming a TCO layer of zinc oxide or tin oxide to make a front electrode is small and significant. In this regard, even small changes in the curing window can negatively affect the conductivity of the TCO layer. When the TCO layer is a single conductive layer of the front electrode, such negative effects can be severely harmful.

Based on this, it can be recognized that there is a need in the field for an improved front electrode for a photovoltaic device that can solve or address one or more of the five problems mentioned above.

General description of the invention

In some representative embodiments of this invention, the front electrode of a photovoltaic device comprises a multilayer coating material comprising a substantially IR-reflective and highly conductive metal layer (e.g., a silver-based layer, gold, or the like), and optionally a At least one permeable conductive oxide (TCO) layer (e.g., made of or including a material such as tin oxide, zinc oxide, or the like). In certain representative cases, the multilayer front electrode coating material may comprise a plurality of TCO layers and/or a plurality of essentially conductive IR reflective metal layers, alternately arranged in order to reduce visible light reflections, increase conductivity, and increase The ability to reflect IR rays, and so on.

In some representative embodiments of this invention, a multilayer coating material for the front electrode can be designed to achieve one or more of the following distinctive properties: (a) Reduced plate resistance (Rs) hence increased conductivity and improved overall output power of a PV module; (b) Increase infrared (IR) reflectance and thus reduce the operating temperature of the photovoltaic module in order to increase the output power of the module; (c) reduce reflection and increase light transmission in the region(s) of approximately 450-700 nm, and/or 450-600 nm, which results in increased output power of the photovoltaic module; (d) Reducing the overall thickness of the front electrode sheathing material Which can reduce manufacturing costs and/or time; And/or (e) improving or expanding the processing window when forming the TCO layer(s) due to the reduced effect of the conductivity of the TCO layers on the overall electrical properties of the module given the presence of a mainly metallic layer(s) that reflects IR and is conductive to a certain extent. big.

In some representative embodiments of this invention, a photovoltaic device is provided comprising: Front glass bracket; Semiconductor film; A substantially permeable front electrode located between at least the front glass substrate and the semiconductor film; Wherein the highly permeable front electrode, as it moves away from the front glass substrate toward the semiconducting film, includes at least one highly permeable layer which may be conductive or non-conductive, a primarily metallic infrared (IR) reflective layer. Comprising silver and/or gold, and a thin conductive oxide (TCO) film placed between at least one layer IR reflective and semiconductor film.

In other exemplary embodiments of this invention, an electrode is provided adapted for use in an electronic device such as a photovoltaic device comprising a semiconductor film, wherein the electrode is: A highly conductive, multilayer electrode supported by a glass substrate; Wherein the highly permeable multilayer electrode, as it moves away from the glass substrate, comprises at least one substantially permeable infrared (IR) reflective (IR) reflective and highly permeable metal layer comprising silver and/or gold, and a conductive first oxide film Outlet (TCO).

In other exemplary embodiments, a photovoltaic device is provided comprising: a glass substrate; Semiconductor film; A substantially permeable electrode located at least between the substrate and the fabricated semiconductor film; Whereas the substantially permeable electrode, as it moves away from the glass substrate toward the semiconducting film, comprises a substantially conductive, substantially metallic layer comprising the silver, and a conductive first oxide (TCO) film disposed at least between the layer comprising the silver And the semiconductor membrane.

Brief explanation of the drawings

Figure 1 is a cross-section view of a representative photovoltaic device according to a representative embodiment of this invention.

Figure 2: A curve showing the refractive index (n) versus wavelength (nm), showing the refractive indices (n) of glass, TCO film, a thin silver film, and hydrogenated silicon (in the amorphous, microcrystalline or polycrystalline phase). crystals).

Figure 3: A curve showing the percentage of transmittance (T%) versus wavelength (nm), showing the transmittance spectra in a hydrogenated Si thin film for a photovoltaic device to compare examples of this invention with a comparative example (reference TCO); This shows that the examples of this invention (Examples 1, 2, and 3) have increased transmittance in the wavelength range of approximately 450-700 nm and thus have helped increase the output power of the typical photovoltaic module, compared to the comparative example (reference TCO).

Figure 4: is a curve showing the percentage of reflectance (R%) versus wavelength (nm), showing the reflectance spectra from a hydrogenated Si thin film of a photovoltaic device in order to compare examples of this invention (Examples 1, 2, and 3 indicated in Figure 3) versus a comparative example (reference TCO indicated in Figure 3); This shows that the representative embodiment of this invention has increased reflectance in the IR range, and this has resulted in a reduction in the operating temperature of the photovoltaic module in order to increase the output power of the module, compared to By comparative example. Since the same examples 1-3 and the comparative example (reference TCO) have been referred to in Figures 3 and 4, the same reference symbols and numbers have been used to designate the parts in both Figures 3 and 4.

Figure 5: A cross-sectional view of the photovoltaic device according to Example No. 1 of this invention.

Figure 6: A cross-section view of a photovoltaic device according to Example No. 2 of this invention.

Figure 7: A cross-section view of a photovoltaic device according to Example No. 3 of this invention.

Figure 8: A cross-section view of a photovoltaic device according to another representative embodiment of this invention.

Figure 9: A cross-section view of a photovoltaic device according to another representative embodiment of this invention.

Figure 10: A cross-section view of a photovoltaic device according to another representative embodiment of this invention.

Figure 11: A cross-section view of a photovoltaic device according to another representative embodiment of this invention.

Detailed description

Referring now more specifically to figures in which similar reference numbers indicate similar parts/layers in multiple views.

Photovoltaic devices, such as solar cells, convert solar radiation into usable electrical energy. Typically, energy conversion occurs as a result of the photovoltaic effect. Where solar radiation (e.g., sunlight) incident on a photovoltaic device is absorbed by an effective region of a semiconductor material (e.g., a semiconductor film comprising one or more semiconductor layers, such as Si The layer manufactured from semiconductors is sometimes called the absorbent layer or absorbent membrane), by generating a pair consisting of an electron and a hole in the active region. Electrons and holes can be separated by an electric field at a junction in a photovoltaic device. The separation of electrons and holes by the junction generates an electric current and an electric voltage. In some exemplary embodiments, electrons flow toward the region of the semiconductor material that has n-type conductivity, and holes flow toward the region of the semiconductor material that has p-conductivity. Current can flow through an external circuit that connects the n-type region to the p-type region while light continues to generate electron-hole pairs in the photovoltaic device.

In some exemplary embodiments, photovoltaic devices made of single-junction amorphous silicon (single-junction Si) comprise three semiconductor layers. Specifically, a p-type layer, an n-type layer, and an i-type layer, which is the original layer. The amorphous silicon film (which can include one or more layers such as p-, n-, and i-type layers) can be hydrogenated amorphous silicon in some cases, but can also be or may include carbon-silica Hydrogenated amorphous germanium cyclone, or the like, in some representative embodiments of this invention. As an example but not limited to, when a light photon is absorbed in layer i, it leads to an increase in the electric current (a pair consisting of an electron and a hole). The p and n layers, which contain charged dopant ions, create an electric field through the i layer that pulls electrical charge out of the i layer and sends it to an optional external circuit where it can provide power to electrical components. It should be noted that while some representative embodiments of this invention have been directed towards photovoltaic devices based on amorphous silicon, this invention is not limited to them and may be used with other types of photovoltaic devices and in some cases including, but not limited to Devices incorporating other types of semiconductor materials, single or double thin film solar cells, CdS and/or CdTe photovoltaic devices (including CdS/CdTe), polysilicon and/or photovoltaic devices Manufactured from Si microcrystalline, and the like.

Figure 1 is a cross-section view of a photovoltaic device according to a representative embodiment of this invention. The photovoltaic device includes a permeable glass front substrate (1) (another suitable substrate material may also be used in place of glass in some cases), optional insulating layer(s) (2), a multilayer front electrode (3), and a semiconductor film Active (5) made of or including one or more semiconductor layers (such as tandem layer stacks such as pin, pn, pinpin, or the like), and a back electrode/contact (7) which may be made of TCO or a metal , and optional encapsulation material (9) or adhesive of a material such as ethylene vinyl acetate (EVA). or similar, and an optional top layer (11) of a material such as glass. Naturally, another layer(s), not described, can be added to the device. The front glass substrate (1) and/or rear overlay (11) may be made of soda-lime (calcium oxide) silica based glass, in some embodiments of this invention; They can have a low iron content and/or an anti-reflective coating applied to them to optimize transmittance in some representative cases. While the substrate(s) (1, 11) may be made of glass in some representative embodiments of this invention, other materials such as quartz, plastic, or the like may be used to fabricate the substrate(s) (1) and/or (11) instead Of glass. Furthermore, the metalayer (11) is optional in some cases. Glass (1) and/or (11) may or may not be heat-tempered and/or heat-formed, in some representative embodiments of this invention. Furthermore, it must be understood that the word "on" as used herein covers both a layer that is placed directly or indirectly on an object, while other layers may be located between it and the object.

The insulating layer(s) (2) may be of any substantially permeable material such as metal oxide and/or metal nitride, which may have a refractive index of from about 1.5 to 2.5, preferably from about 1.6 to 2.5, preferably from About 1.6 to 2.2, preferably about 1.6 to 2, and most preferably about 1.6 to 1.8. However, in some cases, the insulating layer (2) can have a refractive index (n) of about 2.3 to 2.5. Examples of materials from which the insulating layer is made (2) include silicon oxide, silicon nitride, silicon oxynitride, zinc oxide, tin oxide, titanium oxide (e.g., TiO2), aluminum oxynitride, aluminum oxide, or mixtures of the foregoing. The insulating layer(s) (2) acts as a protective layer in some embodiments of this invention, in order to prevent substances such as sodium from migrating outward from the glass substrate (1) and reaching the IR reflective and/or semiconducting layer(s). Furthermore, the insulating layer (2) is a material with a refractive index (n) in the range described above, in order to reduce the reflection of visible light and thus increase the transmittance of visible light (eg, light with a wavelength of about 450- 700 nm and/or 450-600 nm) through the coating layer and into the semiconductor (5) resulting in increased output power of the photovoltaic module.

Continuing with reference to Figure 1, the multilayer front electrode (3) in the representative embodiment shown in Figure 1, which is provided for representational purposes only and not for purposes of limitation, includes, starting at the glass substrate (1) and moving outward, a conductive oxide layer Permeable (TCO) or first dielectric layer (3a), first primarily metallic IR-reflecting and conducting layer (3b), second TCO layer (3c), second primarily metallic IR-reflecting and conducting layer (3d), third TCO layer (3E), and optional protective layer (3F). Optionally, layer 3a can be an insulating layer instead of the TCO layer in some cases and act as a core layer for layer 3b. This multilayer membrane (3) forms the front electrode in some representative embodiments of this invention. Naturally, some of the electrode layers (3) may be removed in some alternative representative embodiments of this invention (e.g., one or more of the layers 3a, 3c, 3d, and/or 3e may be removed), and it may also be possible to provide Additional layers in the multilayer electrode (3). The front electrode (3) may extend continuously across all or a significant portion of the glass substrate (1), or alternatively may be patterned to have a desired design (e.g., strips), in various exemplary embodiments of this invention. Each of the layers/membranes (1-3) is substantially permeable in some representative embodiments of this invention.

The two IR-reflecting layers, the first and second conductors 3B and 3D, may be made of either essentially metallic metal, or may include any suitable IR-reflecting material such as silver, gold, or the like. These materials reflect large amounts of IR rays, and this leads to a reduction in the amount of IR that reaches the semiconductor membrane (5). Since IR increases the temperature of the device, reducing the amount of IR radiation reaching the semiconductor film 5 is beneficial in that it reduces the operating temperature of the photovoltaic module resulting in an increase in the output power of the photovoltaic module. Furthermore, the highly conductive nature of such mainly metallic layers (3b) and/or (3d) enables an increase in the overall electrode conductivity (3). In some representative embodiments of this invention, the multilayer electrode (3) has a plate resistance of less than or equal to about 12 ohms/square, better of less than or equal to about 9 ohms/square, and even better of less than or equal to about 6 ohms/square. Again, increasing conductivity (which also means reducing plate resistance) increases the total output power of the photovoltaic module, by reducing losses due to resistance in the side direction in which the current is to be controlled at the cell cutting edge. It should be noted that the primarily metallic IR-reflecting and conductive first and second layers (3b) and (3d) (as well as the other layers of electrode 3) are thin enough to be highly permeable to visible light. In some representative embodiments of this invention, the thickness of the first and second essentially metallic IR-reflecting and conducting layers (3b) and (3d) ranges from about 3 to 12 nm, preferably from about 5 to 10 nm, and more preferably from about 5 nm. to 8 nm. In embodiments where neither layer 3b or 3d is used, the thickness of the remaining essentially metallic IR-reflecting and conducting layer can range from about 3 to 18 nm, preferably from about 5 to 12 nm, and most preferably from about 6 nm. to 11 nm in some representative embodiments of this invention. These thicknesses (plural thickness) are desirable in that they allow the 3B and/or 3D layers to reflect a large amount of IR radiation, while at the same time being highly permeable to the visible radiation that allows it to reach the semiconductor 5 for conversion by the photovoltaic device. into electrical energy. The highly conductive IR-reflecting layers (3b) and (3d) contribute to the overall conductivity of electrode (3) to a much greater extent than the TCO layers. This allows expanding the processing window(s) of TCO layer(s) that have limited window area to achieve both high conductivity and permeability.

The first, second, and third TCO layers 3a, 3c, and 3e, respectively, may be of any suitable TCO material including, but not limited to, conductive forms of zinc oxide, zinc aluminum oxide, tin oxide, indium oxide - Tin, indium zinc oxide (which can be treated by doping with silver), or the like. These layers typically have equivalent sub-quantities in order to make them conductive according to what is known in the field. For example, these layers are made of material(s) that give them a resistance of no more than about 10 ohm cm (preferably not more than 1 ohm cm, and most preferably no more than about 20 ohm cm). One or more of these layers may be treated by doping with other materials such as fluorine, aluminum, antimony, or the like, in some representative cases, as long as they remain highly conductive to visible light. In some representative embodiments of this invention, the TCO layers (3c) and/or 3e are thicker than the layer (3a) (e.g., at least about 5 nm thicker, at least about 10 more preferably, at least about 20 or 30 nm thicker at least). In some representative embodiments of this invention, the thickness of the TCO layer (3a) ranges from about 3 to 80 nm, preferably from about 10 nm, having a representative thickness of about 10 nm. The optional layer (3a) is provided primarily as a core layer for layer (3b) and/or for anti-reflection purposes, and its conductivity is not as important as that of layers 3b 3e (therefore, layer 3a can be an insulator instead of a TCO layer in some embodiments representation). In some representative embodiments of this invention, the thickness of the TCO layer (3c) ranges from about 20 to about 150 nm, preferably from about 40 to 120 nm, having a representative thickness of about 74 75 nm. In some representative embodiments of this invention, the TCO (3e) layer has a thickness ranging from about 20 to 180 nm, preferably from about 40 to 130 nm, having a representative thickness of about 94 or 115 nm. In some representative embodiments of this invention, a portion of the layer (3e) has a thickness of, for example, about 1-25 nanometers or 5-25 nanometers, at the junction between layers (3e) and (5) and may be replaced by a membrane. Low conductivity with a large refractive index (n) (3F) such as titanium oxide in order to enhance light transmittance as well as reduce back diffusion of generated electric charge carriers; In this way the performance can be improved better.

In some representative embodiments of this invention, the photovoltaic device can be fabricated by providing a glass substrate (1), then depositing (e.g., by sputtering or other suitable method) the multilayer electrode (3) on the substrate (1). The structure including the substrate (1) and front electrode (3) is then coupled with the rest of the device to form the photovoltaic device shown in Figure 1. For example, the semiconductor layer (5) can then be formed over the front electrode on substrate 1. Alternatively, the back contact (7) and semiconductor (5) may be fabricated/formed on the substrate 11 (e.g., of glass or other suitable material) first; The electrode (3) and insulating layer (2) are then formed on the semiconductor (5) and encapsulated by the substrate 1 by an adhesive such as EVA.

The different nature of the TCO layers 3a, 3c, and/or 3e, and the two mainly metal IR-reflecting and conducting layers 3b and/or 3d, are also useful in achieving one, two, three, four, or all The following benefits: (a) Lower plate resistance (Rs) of the overall electrode 3 thus increasing the conductivity and improving the overall output power of a PV module; (b) increasing the infrared (IR) reflection by electrode 3 and thus reducing the operating temperature of the semiconductor portion 5 of the photovoltaic module in order to increase the output power of the module; (c) Reducing the reflection and/or increasing the transmission of light in the visible region of 450-700 nm (and/or 450-600 nm) by the front electrode 3. This leads to an increase in the output power of the unit. Typical photovoltaics; (d) Reducing the overall thickness of the front electrode packing material 3 which can reduce manufacturing costs and/or time; and/or (e) improving or enlarging the curing window when forming the TCO layer(s) due to the reduced effect of the conductivity of the TCO layers on the overall electrical properties of the module given the presence of a primarily metal layer(s) that is highly conductive.

The active semiconductor region or active semiconductor film (5) may comprise one or more layers and may be of any suitable material. For example, the active semiconductor film (5) of a type of photovoltaic device with single-junction amorphous silicon (a-Si) comprises three semiconductor layers, namely p-layer, n-layer, and i-layer. The p-type a-Si layer of the semiconductor film (5) may form the upper part of the semiconductor film (5) in some embodiments of this invention; Typically, the I layer is located between the p and n layers. These amorphous silicon-based layers of the membrane (5) may be made of hydrogenated amorphous silicon in some cases, but can also be made of or can comprise hydrogenated amorphous silicon carbon, hydrogenated amorphous silicon germanium, or microcrystalline silicon. hydrogenated, or other suitable substance(s) in some representative embodiments of this invention. The active region may be of the double-junction or triple-junction type, in alternative embodiments of this invention. CdTe can also be used to fabricate a semiconductor film (5), in alternative embodiments of this invention.

The contactor, reflector, and/or back electrode 7 may be made of any suitable electrically conductive material. Without limitation, the contact or back electrode (7) may be made of TCO and/or metal in some cases. Examples of TCO materials suitable for use as a contact or background electrode (7) include indium zinc oxide, indium tin oxide (ITO), tin oxide, and/or zinc oxide where it may be doped with aluminum (which may or may not be doped with silver). The back contact (7) can be of single-layer type or multi-layer type in different cases. Furthermore, the back contact (7) can include both a TCO portion and a metal portion in some cases. For example, in an example of a multi-layer embodiment, the TCO portion of the back contact (7) may include a layer of a material such as indium zinc oxide (which is doped or undoped with silver), indium tin oxide (ITO), tin oxide, and/ or zinc oxide, as close as possible to the active region (5), and the back contact may include another conductive and possibly reflective layer of a material such as silver, molybdenum, platinum, steel, iron, niobium, titanium, chromium, bismuth, antimony. , or aluminum, furthest from the active zone (5) And closer to the superstratum (11). The metal part can be closer to the epitaxial layer (11) compared to the TCO part of the back contact (7).

The photovoltaic module may be encapsulated or partially covered with an encapsulation material such as encapsulation material (9) in some exemplary embodiments. A representative encapsulation material or layer adhesive (9) is EVA or PVB. However, other materials such as Tedlar type plastic, Nuvasil type plastic, Tefzel type plastic or similar can be used for the layer (9) in different cases.

The use of the two essentially metal, IR-reflecting, and highly conductive layers 3b and 3d, and the TCO layers 3a, 3c, and 3d, to form a multilayer front electrode (3), allows for improving the performance of the thin-film photovoltaic device by reducing the plate resistance ( And increase conductivity) and reflectance and transmission spectra of light planned as needed to best suit the response of the photovoltaic device. The refractive indices of glass 1, hydrogenated a-Si as an example of a semiconductor (5), Ag as an example of layers 3b and 3d, and an example of TCO oxide, are shown in Figure 2. Based on these refractive indices (n), the expected transmittance spectra are shown. For rays that strike the semiconductor (5) from the incident surface of the substrate (1), in Figure 3. Specifically, Figure 3 is a curve showing percentage transmittance (T%) versus wavelength (nm), showing the transmittance spectra to a hydrogenated Si thin film (5) for a photovoltaic device to compare Examples 1-3 of this invention ( See Examples 1-3 in Figures 5-7) versus a comparative example (reference TCO). The TCO referred to as a reference was manufactured from a glass substrate (1) with a thickness of 3 mm, and extending outward starting from the glass, we find a tin oxide layer with a thickness of 3 nanometers, a silicon oxide layer with a thickness of 20 nanometers, and a TCO layer with a thickness of 350 nanometers. Therefore, Figure 3 shows that the examples of this invention (Examples 1-3 shown in Figures 5-7) have increased the transmittance in the wavelength range from 450-600 and 450-700 nanometers, and this has led to an increase in the output power of the typical photovoltaic unit. , compared to the comparative example (reference TCO).

Example 1, shown in Figure 5 and shown graphically in Figures 3-4, was manufactured from a glass substrate (1) 3 mm thick, an insulating layer (2) of TiO2 16 nm thick, and a TCO layer of 10 nm thick zinc oxide doped with Al (3a), an 8 nm thick IR reflective Ag (3b) layer, and a 115 nm thick TCO layer doped with Al (3e). Layers 3C, 3D, and 3F were not present in Example 1. Example 2 shown in Figure 6 and shown graphically in Figures 3-4 was made of a 3 mm thick glass substrate (1), an insulating layer (2) of 16 nm thick TiO2, and a TCO layer of 10 nm thick zinc oxide doped with Al. (3a), an 8 nm thick IR reflective Ag layer (3b), a 100 nm thick TCO layer doped with Al (3e), and a 20 nm thick TiO layer (3f). Example 3 shown in Figure 7 and shown graphically in Figures 3-4 was fabricated from a 3 mm thick glass substrate (1), a 45 nm thick insulating layer (2), and a 10 nm thick TCO layer of zinc oxide doped with Al (3a). A 5 nm thick IR-reflecting Ag layer (3b), a 75 nm thick TCO layer of zinc oxide doped with AL (3c), a 7 nm thick IR-reflecting Ag layer (3d), and a semi-oxide layer (3f). Titanium thickness 20 nanometers. These single- or double-layer silver coatings used in Examples 1-3 had plate resistances of less than 10 ohms/square and 6 ohms/square, respectively, and had an overall thickness much less than the 400 nm thickness used. In prior art. Examples 1-3 had transmittance spectra plotted as needed, as shown in Figure 3, with a transmittance greater than 80% to the semiconductor (5) in part or all of the wavelength range of about 450-600 nm and/or 450-700 nm, where AM1.5 had the strongest intensity and photovoltaic devices can have substantially higher or higher quantum efficiencies.

Meanwhile, Figure 4 is a curve showing the percentage of reflectance (R%) versus wavelength (nm) showing the reflectance spectra from a hydrogenated Si thin film for a photovoltaic device to compare Examples 1-3 to the aforementioned comparative example; This shows that Examples 1-3 have increased reflectivity in the IR range which reduces the operating temperature of the photovoltaic module resulting in increased module output, compared to the comparative example. In Figure 4, the decrease in reflectance in the visible range of about 450-600 nm and/or 450-700 nm (the high efficiency range of the cell) is advantageously coupled with the increase in reflectance in the near and short IR range above about 1000 nm. ; Increased reflectance in the near and short IR range reduces the absorption of solar thermal energy, leading to improved cell output due to lower cell temperature and series resistors in the module. As shown in Figure 4, both the front glass substrate (1) and the front electrode (3) combined have a reflectivity of at least about 45% (and preferably at least about 55%) over a fairly large portion or most of the range. The near to short wavelength of IR rays ranges from about 100-2500 nm and/or 1000-2300 nm. In some representative embodiments, they reflect at least 50% of the energy in the range 1000-2500 nm and/or 1200-2300 nm. In some representative embodiments, the front glass substrate and front electrode (3) combined have an IR reflectivity of at least about 45% and/or at least 55% over a fairly large portion or most of the near IR wavelength range of About 1000-2500 nm, and can be 1200-2300 nm. In some representative embodiments, they can block at least 50% of solar energy in the range of 1000-2500 nm.

While electrode (3) is used as a front electrode in a photovoltaic device in some representative embodiments of this invention that are described and illustrated herein, electrode (3) may also be used as a second electrode in connection with a photovoltaic device or otherwise.

Figure 8 is a cross-section view of a photovoltaic device according to another representative embodiment of this invention. An optional anti-reflective (AR) layer (1a) may be provided on the front glass substrate (1) in any embodiment of this invention, as referred to for example as the AR layer(s) (1a) shown in Figure 8 (e.g. (See also Figures 9-10). The photovoltaic device of Figure 8 includes a glass substrate (1), insulating layer(s) (2) (e.g., made of or comprising one or more of silicon oxide, silicon oxynitride, silicon nitride, titanium oxide, niobium oxide , and/or the like) which may act as a sodium barrier to prevent sodium from moving off the anterior glass substrate (1); and the core layer (4b) (e.g., made of or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, indium zinc oxide, or the like) which may The TCO layer or buffer layer is in various representative embodiments; and a silver-based IR reflective layer (4c), and an optional top coating or contact layer (4d) (e.g., made of or comprising Ni and/or Cr oxide, ZnO, ZnO, or the like) which can TCO layer formation; and TCO (4e) layer (e.g., made of or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, indium tin oxide, zinc indium oxide, or the like); Optional protective coating, (for example, made of or including zinc oxide, aluminum zinc oxide, tin oxide, antimony tin oxide, indium tin oxide, zinc indium oxide, or the like) where it may be conductive to some extent; semiconductor (5) (e.g., CdS/CdTe, a-Si, or similar); Optional contactor, reflector, and/or back electrode (7); Optional adhesive layer (9), optional back glass substrate 11. It should be noted that in some representative embodiments, layer (4b) may be the same as layer (3a) previously described above, and layer (4c) may be the same as layer (3b) or (3d) previously described above, ( This also applies to Figures 8-10, and layer (4f) could be the same as layer (3f) that was previously described above (this also applies to Figures 8-10) (see the advanced description above for an explanation of other models in this regard). Likewise, layers 1, 5, 7, 9, and 11 have also been discussed above in relation to other models.

For illustrative purposes only, an example of a Figure 8 template will be provided as follows (note that some of the optional layers shown in Figure 8 are not used in this example). For example, referring to Figure 8, a glass substrate (1) was used (e.g., about 3.2 mm thick), and a dielectric layer (2) (e.g., silicon oxynitride with a thickness of about 20 nm can be followed by a dielectric TiOx layer with a thickness of about 20 nm), an Ag core layer (4b) (e.g., a dielectric layer, TCO layer, or ZnO layer about 10 nm thick), and an IR reflective layer (4c) (of silver, about 5-8 nm thick ), TCO (4e) layer (e.g., ZnO, TnO, ITO, conductive layer with a thickness of 50- 250 nanometers) and preferably about 100-150 nm), and an optional conductive protective layer (4F) (zinc oxide TCO, tin oxide, zinc aluminum oxide ITO, or similar, with a thickness of about 10-50 nm). In some representative embodiments, the protective layer 4f (or 3f) is designed to have a refractive index (n) of about 2.1 to 2.4, preferably from about 2.15 to 2.35, where the refractive index closely matches that of the semiconductor (5) ( such as, CdS or similar) in order to improve the efficiency of the device.

The photovoltaic device shown in Figure 8 may have a plate resistance of not more than about 18 ohms/square, and preferably not more than about 15 ohms/square, and preferably not more than about 13 ohms/square in some representative embodiments of this invention. Furthermore, the model shown in Figure 8 can have transmittance spectra plotted as needed with a transmittance greater than 80% to the semiconductor (5) in part or all of the wavelength range of about 450-600 nm and /or 450-700 nm, where AM1.5 can have the greatest density and in some representative cases the cell has the highest or substantially the highest quantum efficiency.

Figure 9 is a cross-section view of a photovoltaic device according to another representative embodiment of this invention. The photovoltaic device of the embodiment shown in Figure 9 includes an optional anti-reflection (AR) layer (1a) on the light incident side of the front glass substrate (1), a first insulating layer (2a), a second insulating layer (2b), and a third insulating layer (3c). ) which can optionally serve as a core layer (e.g., made of or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, indium zinc oxide, or the like) of the silver-based layer (4C), and a reflective conductive layer For infrared IR based on silver (4C), top coating or An optional contact layer (4d) (e.g., made of or comprising Ni and/or Cr oxide, ZnO, ZnO, or the like) which may be TCO or insulating, and an RCO layer (4e) (e.g., comprising on one or more layers, for example made of or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, tin zinc oxide, indium tin oxide, indium zinc oxide, or the like), and an optional protective layer (4f) (For example, manufactured from or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, tin zinc, indium tin oxide, indium zinc oxide, or the like) where they may be more or less conductive, semiconducting (5) (e.g., one or more layers such as CdS/CdTe, a-Si or the like) , optional contactor, reflector, and/or electrode back (7), optional adhesive layer (9), and optional back glass substrate (11). The semiconductor film (5) can comprise a single pin or pn semiconductor structure, or a double semiconductor structure in various embodiments of this invention. The semiconductor may be, or may comprise, silicon in some exemplary cases. In other exemplary embodiments, the semiconductor film (5) may comprise a first layer made of or comprising CdS (e.g., a permeable layer) adjacent or close to the layer(s) (4e) and/or (4f) and a second semiconductor layer Manufactured from or including CdTe (e.g., main absorbent layer) adjacent or close to the electrode or back contact 7.

Referring to an embodiment of Fig. 9 (and an embodiment of Fig. 10), in some representative embodiments, a first dielectric layer (2a) with a relatively low refractive index (n) is used (e.g., n ranging from about 1.7 to 2.2, preferably from about 1.8 to 2.2, Better still from about 1.95 to 2.1, most preferably from about 2 to 2.08), and a second insulating layer (4b) with a relatively large refractive index (n) (compared to layer (2a)) (e.g., n ranging from about 2.2 to 2.6, The best is from about 2.3 to 2.5, and the most preferable is from about 2.35 to 2.45, and a third insulating layer (2C) with Relatively low refractive index (n) (compared to layer 2b) (e.g., n ranges from about 1.8 to 2.2, preferably from about 1.95 to 2.1, most preferably from about 2 to 2.05). In some exemplary embodiments, the first low-refractive index insulating layer (2a) can be made of, or may comprise, silicon nitride, silicon oxynitride, or other suitable material, and the second high-refractive index insulating layer (2b) can be made of, or may comprise, titanium oxide (e.g., TiO2 or the like), and the third insulating layer (2c) may be made of, or may comprise, zinc oxide or other suitable material. In some representative embodiments, layers 2a-2c are combined to form a combined layer with a compatible good refractive index that also serves as a protective layer against sodium migration from the glass (1). In some exemplary embodiments, the thickness of the first insulating layer (2a) ranges from about 5 to 30 nm, preferably from about 10 to 20 nm, and the thickness of the second insulating layer (2b) ranges from about 5 to 30 nm, preferably from about 10 nm. - 20 nanometers, and the third insulating layer (2C) is thinner and its thickness ranges from about 3-20 nanometers, preferably from about 5-15 nanometers, and most preferably from about 6-14 nanometers. While layers 2a, 2b, and 2c are insulating in some embodiments of this invention, one, two, or all three of these layers may be insulating or TCO in some other representative embodiments of this invention. Layers (2b) and (2c) are metal oxides in some representative embodiments of this invention, while layer (2a) is metal oxide, metal nitride, or silicon nitride in some representative cases. Layers 2a and 2c can be deposited by spraying or any other suitable method.

Also referring to Embodiment of Figures 9 (and Embodiments of Figures 10 - 11), the TCO layer(s) (4e) may be made of or may comprise a suitable TCO including, without limitation, zinc oxide, and/or zinc oxide. Aluminum, tin oxide, and/or the like. A TCO layer or TCO row (4e) can include multiple layers in some representative cases. For example, in some cases, the TCO layer (4) comprises a first TCO layer (e.g., zinc oxide) adjacent to the Ag layer (4c), an Ag top coating layer (4d), and a second TCO layer (e.g., tin oxide) close to the contact layer (4f) and/or (5).

For illustrative purposes only, an example of a sample figure of Figure 9 is shown as follows. For example, referring to Figure 9, a glass substrate (1) (e.g., bulk glass with a thickness of about 3.2 mm, with a refractive index (n) of about 1.52) was used, and a first dielectric layer (2a) (e.g., silicon nitride with a thickness of about 15 nm) was used. , with a refractive index (n) of about 2.07), a second insulating layer (2b) (e.g., Ti oxide, such as TiO2 or other suitable equivalent material, about 16 nm thick, with a refractive index (n) of about 2.45), and a third insulating layer (2c) (e.g., ZnO, possibly doped with Al, about 9 nm thick, with a refractive index (n) of about 2.03), and a layer IR-reflecting (4c) (silver 5-8 nm thick, e.g. 6 nm), and a top covering layer containing silver (4d) made of NiCrOx 1-3 nm thick which can be or Non-oxidation gradient, TCO film (4e) (e.g., ZnO, ZnO, and/or tin oxide, conductive, 10-150 nm thick), and semiconducting film (5) comprising a first layer of CdS (e.g., about 70 nm) as close as possible to the substrate (1) and a second layer of CdTe furthest from the substrate (1), and a contact or back electrode (7), Optional adhesive layer (9), optional substrate 11.

The photovoltaic device shown in Figure 9 (and/or Figures 10 - 11) can have a plate resistance of no more than about 18 ohms/square, and preferably not more than 15 ohms/square, and even better not more than 13 ohms/square in Some representative examples of this invention. Furthermore, a sample of Figure 9 (and/or Figure 10) can have transmittance spectra plotted as needed with a transmittance greater than 80% in the semiconductor (5) in part or all of the wavelength range of about 450-600. nm and/or 450-700 nm, where AM1.5 can have the greatest intensity.

Figure 10 is a cross-section view of a photovoltaic device according to another representative embodiment of this invention. The model of Figure 10 is completely similar to the model of Figure 9 discussed above, except for the TCO membrane (4e). In an embodiment of Figure 10, the TCO film (4e) includes a first layer (4e) made of or comprising a first TCO metallic oxide (e.g., zinc acid, which may or may not be doped with Al or the like) adjacent to and in contact with the layer (4d); and a second layer (4e) of a second TCO metallic oxide (e.g., tin oxide) adjacent to and in contact with layer (4f) and/or (5) (e.g., layer (4f) may be omitted, as in previous embodiments). Layer 4e is considerably thicker than layer 4e in some representative models. In some representative embodiments, the first TCO layer (4e) has a greater resistivity than the second TCO layer (4e). In some exemplary embodiments, the first TCO layer (4e) can be ZnO, Al-doped ZnO, or ITO, having a thickness of 70-150 nm (e.g., about 110 nm) and having a resistivity of no more than About 1 ohm. cm, and the second TCO layer (4Ha) can be made of tin oxide and range in thickness from about 10-50 nm (eg, about 30 nm) and have a resistivity of about 10-100 ohms. cm, and it can range from about 2-100 ohms. poison. The first TCO layer (4e) is thicker and has a higher conductivity than the second TCO layer (4e) in some representative models, and this is useful as the layer (4e) is closer to the Ag-based conductive layer (4c) and this leads to improving the efficiency of the photovoltaic device. . Moreover, this design is unique in that the CdS of the film (5) adheres well to the tin oxide that can be used in the layer (4e) or can be made from it. The TCO 4e and/or (4e) layers can be deposited by spraying or other suitable method.

In some representative cases, the first TCO layer (4e) may be made from or comprise ITO (indium tin oxide) instead of zinc oxide. In some representative cases, the ITO oxide of layer 4e may comprise about 90% In, 10% Sn, or alternatively about 50% In, 50% Sn.

Using at least three dielectric layers such as 2a-2c is beneficial in that reflections can be reduced resulting in a more efficient photovoltaic device. Furthermore, the top coat layer 4d (e.g., made of or comprising Ni and/or Cr oxide) may be oxidation graded, continuous or discontinuous, in some embodiments of this invention. Specifically, layer 4d can be designed to be more metallic (less oxidized) at a position closer to the Ag-based layer (4d) than at a position further away from the Ag-based layer (4d); This has been found to be beneficial for thermal stability purposes in that the coating does not degrade significantly during the extremely high temperature processing that can accompany photovoltaic device manufacturing or any other process.

In some representative embodiments of this invention, it has been interestingly found that any thickness of about 120-160 nm, preferably about 130-150 nm (e.g., 140 nm), of the TCO membrane (4e) is advantageous in that Jsc peaks in this range. For thinner TCO films, the Jsc peaks decrease by up to about 6.5% until reaching a minimum at a TCO thickness of about 60 nm. Below 60 nm, it increases again until a TCO (4e) film with a thickness of 15-35 nm (preferably 20-30 nm) becomes attractive, but such coating layers may not be desirable in some representative cases. Non-exclusive. Therefore, to obtain a reduction in short-circuit current for CdS/CdTe photovoltaic devices in some representative cases, a TCO (4e) film may be provided with thicknesses in the range of about 15-35 nm, or in the range of about 120 nm. - 160 nm or 130-150 nm.

Figure 11 is a cross-section view of a photovoltaic device according to another representative embodiment of this invention. The model of Figure 11 is completely similar to the models of Figure 9 11 previously discussed above, except for the differences shown in the figure. Figure 11 is a cross-section view of a photovoltaic device according to another representative embodiment of this invention. The photovoltaic device shown in Figure 11 may include: Optional anti-reflection (AR) coating (1a) on the light incident side of the front glass substrate 1; A first insulating layer (2a) made of or comprising one or more silicon nitride (e.g., Si3N4 or other suitable chemical equivalent), silicon oxynitride, silicon oxide (e.g., SiO2 or other suitable chemical equivalent), and/or oxide Tin (e.g., SnO2 or other suitable chemical equivalent); a second insulating layer (3b) made of or comprising titanium oxide (e.g., TiO2 or other suitable chemical equivalent) and/or niobium oxide; A third layer (2C) (can be insulating or... TCO layer) which may optionally serve as a core layer (e.g., a layer made of or comprising zinc oxide, zinc aluminum oxide, tin oxide, tin antimony oxide, indium zinc oxide, or the like) for the silver-based layer (4C); A top coating or contact layer 4d (which may be insulating or conducting) is made of or includes an oxide of Ni and/or Cr, NiCr, Ti, Ti oxide, ZnO, or the like; TCO (4e) layer (e.g., comprising one or more layers) made of or comprising zinc oxide, zinc aluminum oxide, oxide Tin, antimony tin oxide, tin zinc oxide, tin indium oxide, zinc indium oxide, and/or aluminum gallium zinc oxide; An optional protective layer (4f) may be TCO in certain cases (e.g., manufactured from or comprising zinc oxide, zinc aluminum oxide, tin oxide, antimony tin oxide, tin zinc oxide, indium tin oxide, indium zinc oxide, titanium oxide, or similar) where it can be somewhat conductive; Semiconductor film (5) made of or comprising one or more layers such as CdS/CdTe, a-Si, or the like (e.g., film (5) may be made of a layer fabricated or comprising CdS adjacent to layer (4f), and a layer fabricated or comprising CdTe adjacent to layer (7) of aluminum or the like; Optional adhesive 9 made of or including a polymer such as PVB; Optional glass backplate 11. In some representative embodiments of this invention, the thickness of the insulating layer 2a can range from about 10 to 12 nm, preferably from about 12 to 18 nm; The thickness of layer 2b can range from about 10-20 nanometers, and preferably from about 12-18 nanometers. The thickness of layer 2c can range from about 5 to 20 nm, preferably from about 5 to 15 nm (with layer 2c being thinner than one or both of layers 2a and 2b in some representative embodiments); The thickness of layer 4c can range from about 5-20 nanometers, and preferably from about 6-10 nanometers. And it can The thickness of the 4D layer ranges from about 0.2 to 5 nm, preferably from about 0.5 to 2 nm; The thickness of the TCO (4e) film can range from about 50-200 nm, preferably from about 75-150 nm, and can have a resistance of no more than about 100 milliohms in some representative cases; The thickness of the barrier layer 4F can range from about 10-50 nanometers, preferably from about 20-40 nanometers, and it can have a resistance not exceeding about 1 megaohm cm in some representative cases. Furthermore, the surface of the glass 1 closest to the sun can be shaped to have a repeating pattern by scratching or the like, in some representative embodiments of this invention.

An optional barrier layer (4f) can provide a substantial refractive index match between the semiconductor film (5) (e.g., the CdS portion) up to the TCO film (4e) in some representative embodiments, in order to improve the overall transmittance of sunlight reaching the semiconductor.

Also referring to embodiments of Figure 11, the semiconductor film (5) may comprise a single pin or pn semiconductor structure, or a tandem semiconductor structure in various embodiments of this invention. The semiconductor film (5) may be embedded or include silicon in some exemplary cases. In other exemplary embodiments, the semiconductor film (5) may comprise a first layer made of or comprising CdS (e.g., a permeable layer) adjacent or closest to the layer(s) 4e and/or 4f and a second semiconductor layer made of or including On the CdTe (e.g., main sorbent) close or closest to the electrode or back contact 7.

Referring also to Figure 11, in some representative embodiments, the first dielectric layer 2a has a relatively low refractive index (n) (e.g., n ranging from about 1.7 to 2.2, preferably from about 1.8 to 2.2, more preferably from about 1.95 to 2.1, and more preferably from about 2 to 2.08), and the second dielectric layer 2b has a relatively high refractive index (n) (compared to layer 2a) (e.g., n ranges from about 2.2 to 2.6, preferably from about 2.3 to 2.5, most preferably from about 2.35 to 2.45 ), and can optionally be used as an insulating layer The third 2C has a relatively low refractive index (n) (compared to 2B) (e.g., n ranges from about 1.8 to 2.2, preferably from about 1.95 to 2.1, most preferably from about 2 to 2.05). In some representative embodiments, layers 2a-2c are combined to form a stack with good refractive index matching for anti-reflective purposes and which also serves as a protective layer to prevent sodium migration from the glass 1. In some exemplary embodiments, the thickness of the first insulating layer 2a ranges from about 5 to 30 nm, preferably from about 10 to 20 nm, and the thickness of the second insulating layer 2b ranges from about 5 to 30 nm, more preferably from about 10 to 20 nm. The third layer, 3C, is thinner and its thickness ranges from about 3-20 nanometers, preferably from about 5-15 nanometers, and most preferably from about 6-14 nanometers. While layers 2a, 2b, and 2c are insulating in some embodiments of this invention, one, two, or all three of these layers may be insulating or TCO in some other representative embodiments of this invention, while layer 2a is oxide and/or metal nitride. Or silicon nitride in other representative cases. Layers 2a-2c can be deposited by spraying or by any other suitable method.

[0060] Also referring to embodiment of Fig. 11, the TCO layer(s) (4e) may be fabricated or may comprise any suitable TCO including but not limited to zinc oxide, zinc aluminum oxide, tin oxide, and/ Or something like that. The TCO layer or membrane (4e) can comprise several layers in some representative cases. For example, in some cases, the TCO layer (4) comprises a first TCO layer (e.g., zinc oxide) adjacent to the Ag layer (4c), a top Ag layer (4d), and a second TCO layer Second (for example, tin oxide close and in contact with layer (4f) and/or (5). The photovoltaic device shown in Figure 11 can have a plate resistance of not more than about 18 ohms/square, and preferably not more than about 15 ohms/square, Better yet, it should not exceed about 13 ohms/square in some representative embodiments of this invention. Furthermore, the model shown in Figure 11 can have transmittance spectra plotted as needed with a transmittance greater than 80% to the semiconductor (5) in part or all of the wavelength range of about 450-600 nm and /or 450-700 nm, where AM1.5 can have the greatest intensity, in some representative embodiments of this invention.

While the invention has been described in relation to what may at present be considered the preferred and most practicable embodiment, it should be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, that the invention is intended to cover various equivalent modifications and arrangements. Which are included within the content and scope of the attached protection elements.