Metal oxynitride back contact layers for photovoltaic devices.

Abstract

To provide a back contact that solves the inoperability and instability of a photovoltaic device. The back contact of a photovoltaic device can include one or more metal oxynitride layers. The back contact can be disposed adjacent to the absorber layer. A first surface of the back contact can be disposed on the second surface of the absorber layer. The back contact can include a binary or ternary combination of materials from Groups I, II, and VI. One or more layers of the back contact can be doped, for example, with one or more Group I dopants. Alternatively or additionally, the back contact can include one or more layers containing a metal nitride material. Alternatively or additionally, the back contact can include one or more layers containing a metal oxynitride material, such as titanium oxynitride, tungsten oxynitride, zirconium oxynitride, or tantalum oxynitride.

Description

[Technical field]

[0001]

[0001] This application claims priority to U.S. patent application Ser. No. 62 / 801,965, filed Feb. 6, 2019, which is incorporated herein by reference.

[0002] This specification relates generally to photovoltaic devices having one or more metal back contact layers, and more particularly to photovoltaic devices having one or more metal oxynitride back contact layers. [Background technology]

[0002]

[0003] Photovoltaic devices generate power by converting light into direct current using semiconductor materials that exhibit the photovoltaic effect. Certain semiconductor materials can be difficult to manufacture. For example, certain dopants provided in a layer of the back contact can diffuse through and throughout the back contact, leading to inoperability or instability of the photovoltaic device.

[0003]

[0004] Thus, a need exists for alternative back contact layers for use in photovoltaic devices. Summary of the Invention

[0004]

[0005]

[0013] The embodiments provided herein relate to photovoltaic devices having improved back contacts. These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description in conjunction with the drawings.

[0005]

[0006] The embodiments described in the drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of exemplary embodiments can be understood when read in conjunction with the following drawings, in which like structure is designated with like numerals and in which: [Brief description of the drawings]

[0006] [Figure 1]

[0007] 1 illustrates generally a cross-sectional view of a photovoltaic device according to one or more embodiments shown and described herein. [Diagram 2]

[0008] 1 illustrates a schematic representation of a substrate according to one or more embodiments shown and described herein. [Diagram 3]

[0009] 1 illustrates generally a cross-sectional view of a photovoltaic device according to one or more embodiments shown and described herein. [Figure 4]

[0010] 2 illustrates a schematic diagram of a back contact according to one or more embodiments shown and described herein. [Diagram 5] 1 illustrates a schematic diagram of a back contact according to one or more embodiments shown and described herein. [Figure 6] 1 illustrates a schematic diagram of a back contact according to one or more embodiments shown and described herein. [Figure 7] 1 illustrates a schematic diagram of a back contact according to one or more embodiments shown and described herein. [Figure 8] 1 illustrates a schematic diagram of a back contact according to one or more embodiments shown and described herein. [Figure 9]

[0011] 2 illustrates a schematic representation of a conductive layer according to one or more embodiments shown and described herein. [Figure 10]

[0012] 1 illustrates a flowchart for forming a back contact according to one or more embodiments shown and described herein. [Figure 11]

[0013] 1 illustrates test results of comparative examples compared to devices according to one or more embodiments shown and described herein. [Figure 12]

[0014] 1 illustrates test results of comparative examples compared to devices according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007]

[0015] Embodiments of photovoltaic devices having metal nitride back contacts are provided herein. Various embodiments of photovoltaic devices and methods for forming photovoltaic devices are described in more detail herein.

[0008]

[0016] Referring now to FIG. 1, an embodiment of a photovoltaic device 100 is shown in schematic form. The photovoltaic device 100 can be configured to receive light and convert the light into an electrical signal, e.g., photons can be absorbed from the light and converted into an electrical signal via the photovoltaic effect. Accordingly, the photovoltaic device 100 can define an energy side 102 configured to be exposed to a light source, e.g., the sun. The photovoltaic device 100 can also define an opposite side 104 that is offset from the energy side 102, e.g., by multiple layers of material. The term "light" can refer to various wavelengths of the electromagnetic spectrum, such as, but not limited to, wavelengths in the ultraviolet (UV), infrared (IR), and visible portions of the electromagnetic spectrum. "Sunlight," as used herein, refers to light emitted by the sun. The photovoltaic device 100 can include multiple layers disposed between the energy side 102 and the opposite side 104. As used herein, the term "layer" refers to a thickness of material provided on a surface. Each layer can cover all or any portion of the surface.

[0009]

[0017] 1 and 2 collectively, the layers of the photovoltaic device 100 may include a substrate 110 configured to facilitate transmission of light into the photovoltaic device 100. The substrate 110 may be disposed on an energy side 102 of the photovoltaic device 100. The substrate 110 may have a first surface 112 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 114 substantially facing an opposite side 104 of the photovoltaic device 100. One or more layers of material may be disposed between the first surface 112 and the second surface 114 of the substrate 110.

[0010]

[0018] The substrate 110 may include a transparent layer 120 having a first surface 122 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 124 substantially facing the opposite side 104 of the photovoltaic device 100. In some embodiments, the second surface 124 of the transparent layer 120 may form the second surface 114 of the substrate 110. The transparent layer 120 may be formed from a substantially transparent material, such as, for example, glass. Suitable glasses may include soda-lime glass or any glass having reduced iron content. The transparent layer 120 may have any suitable transmittance, including, in some embodiments, from about 250 nm to about 1,300 nm, or in other embodiments, from about 250 nm to about 950 nm. The transparent layer 120 may have any suitable transmittance, including, for example, greater than about 50% in one embodiment, greater than about 60% in another embodiment, greater than about 70% in yet another embodiment, greater than about 80% in a further embodiment, or greater than about 85% in yet another embodiment. In one embodiment, the transparent layer 120 may be formed from glass having a transmittance of about 90% or greater. Optionally, the substrate 110 may include a coating 126 applied to the first surface 122 of the transparent layer 120. The coating 126 may be configured to interact with light or improve the durability of the substrate 110, such as, but not limited to, an anti-reflective coating, an anti-soiling coating, or a combination thereof.

[0011]

[0019] 1, the photovoltaic device 100 may include a barrier layer 130 configured to mitigate the diffusion of contaminants (e.g., sodium) from the substrate 110 that may result in degradation or delamination. The barrier layer 130 may have a first surface 132 that substantially faces the energy side 102 of the photovoltaic device 100 and a second surface 134 that substantially faces the opposite side 104 of the photovoltaic device 100. In some embodiments, the barrier layer 130 may be disposed adjacent to the substrate 110. For example, the first surface 132 of the barrier layer 130 may be disposed on the second surface 114 of the substrate 100. The phrase "adjacent to" as used herein means that two layers are disposed in contact and do not have any intervening material between at least a portion of the layers.

[0012]

[0020] In general, the barrier layer 130 may be substantially transparent, thermally stable, have a low number of pinholes, have a high sodium blocking capability, and have good adhesion. Alternatively or additionally, the barrier layer 130 may be configured to apply color suppression to the light. The barrier layer 130 may include one or more layers of suitable materials, including, but not limited to, tin oxide, silicon dioxide, aluminum doped silicon oxide, silicon oxide, silicon nitride, or aluminum oxide. The barrier layer 130 may have any suitable thickness (including, for example, greater than about 100 Å in one embodiment, greater than about 150 Å in another embodiment, or less than about 200 Å in a further embodiment) bounded by the first surface 132 and the second surface 134.

[0013]

[0021] 1, the photovoltaic device 100 can include a transparent conductive oxide (TCO) layer 140 configured to provide electrical contacts and transport charge carriers generated by the photovoltaic device 100. The TCO layer 140 can have a first surface 142 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 144 substantially facing the opposite side 104 of the photovoltaic device 100. In some embodiments, the TCO layer 140 can be disposed adjacent to the barrier layer 130. For example, the first surface 142 of the TCO layer 140 can be disposed on the second surface 134 of the barrier layer 130. In general, the TCO layer 140 can be formed from one or more layers of a substantially transparent, wide bandgap n-type semiconductor material. In particular, the wide bandgap can have a large energy value compared to the energy of the photons of light, mitigating unwanted light absorption. The TCO layer 140 may be any suitable material, including, but not limited to, tin oxide, fluorine doped tin oxide (e.g., F:SnO, F:SnO2, or F:SnO x The insulating layer may include one or more layers of a suitable material including, for example, tin oxide, indium tin oxide, or cadmium stannate.

[0014]

[0022] The photovoltaic device 100 may include a buffer layer 150 configured to provide an insulating layer between the TCO layer 140 and any adjacent semiconductor layers. The buffer layer 150 may have a first surface 152 that substantially faces the energy side 102 of the photovoltaic device 100 and a second surface 154 that substantially faces the opposite side 104 of the photovoltaic device 100. In some embodiments, the buffer layer 150 may be disposed adjacent to the TCO layer 140. For example, the first surface 152 of the buffer layer 150 may be disposed on the second surface 144 of the TCO layer 140. The buffer layer 140 may be made of a material having a higher resistivity than the TCO layer 140, such as, but not limited to, intrinsic tin oxide (SnO, SnO2 or SnO x ), magnesium oxide (MgO), magnesium zinc oxide (e.g., Zn 1-x Mg x O), silicon dioxide (SiO2), manganese oxide (MnO x), silicon nitride (SiN x ) or any combination thereof, etc.

[0015]

[0023] The photovoltaic device 100 can include an absorbing layer 160 configured to cooperate with another layer to form a p-n junction within the photovoltaic device 100. In response, absorbed photons of light can liberate electron-hole pairs, generating carrier flux and generating electrical power. The absorbing layer 160 is substantially The absorbing layer 160 may have a first surface 162 facing the opposite side 104 of the photovoltaic device 100 and a second surface 164 facing substantially the opposite side 104 of the photovoltaic device 100. A thickness of the absorbing layer 160 may be defined between the first surface 162 and the second surface 164. The thickness of the absorbing layer 160 may be from about 0.5 μm to about 10 μm, such as from about 1 μm to about 7 μm in one embodiment, or from about 1.5 μm to about 4 μm in another embodiment.

[0016]

[0024] According to embodiments described herein, the absorbing layer 160 may be formed from a p-type semiconductor material having an excess of positive charge carriers, i.e., holes or acceptors. The absorbing layer 160 may include any suitable p-type semiconductor material, such as a II-VI semiconductor. Specific examples include, but are not limited to, semiconductor materials that include cadmium, tellurium, selenium, or any combination thereof. Suitable examples include, but are not limited to, cadmium, selenium, and tellurium ternary compounds (e.g., CdSe x Te 1-x ), or compounds containing cadmium, selenium, tellurium, and one or more additional elements.

[0017]

[0025] In embodiments in which the absorbing layer 160 includes tellurium and cadmium, the atomic percentage of tellurium may be greater than or equal to about 25 atomic percent and less than or equal to about 50 atomic percent, such as greater than about 30 atomic percent and less than about 50 atomic percent in one embodiment, greater than about 40 atomic percent and less than about 50 atomic percent in a further embodiment, or greater than about 47 atomic percent and less than about 50 atomic percent in yet another embodiment. Alternatively or additionally, the atomic percentage of tellurium in the absorbing layer 160 may be greater than about 45 atomic percent, such as greater than about 49% in one embodiment. It should be noted that the atomic percentages described herein are representative of the entire absorbing layer 160, and that the atomic percentage of a material at a particular location within the absorbing layer 160 may vary with thickness as compared to the overall composition of the absorbing layer 160.

[0018]

[0026] In embodiments in which absorbing layer 160 includes selenium and tellurium, the atomic percentage of selenium in absorbing layer 160 may be greater than about 0 atomic percent and less than or equal to about 25 atomic percent, e.g., in one embodiment greater than about 1 atomic percent and less than about 20 atomic percent, in another embodiment greater than about 1 atomic percent and less than about 15 atomic percent, or in a further embodiment greater than about 1 atomic percent and less than about 8 atomic percent. It is noted that the concentration of tellurium, selenium, or both may vary through the thickness of absorbing layer 160. For example, when absorbing layer 160 includes a compound including a mole fraction of x selenium and a mole fraction of 1-x tellurium (Se x Te 1-x ), x can vary in the absorbing layer 160 depending on the distance from the first surface 162 of the absorbing layer 160.

[0019]

[0027] 1 , the absorbing layer 160 can be doped with a dopant configured to manipulate the concentration of charge carriers. In some embodiments, the absorbing layer 160 can be doped with a dopant, such as, for example, one or more Group I dopants, one or more Group V dopants, or a combination thereof. The total density of dopants in the absorbing layer 160 can be controlled. Alternatively or additionally, the amount of dopant can vary with distance from the first surface 162 of the absorbing layer 160.

[0020]

[0028] According to embodiments provided herein, a p-n junction can be formed by providing the absorbing layer 160 sufficiently close to a portion of the photovoltaic device 100 having an excess of negative charge carriers, i.e., electrons or donors. In some embodiments, the absorbing layer 160 can be provided adjacent to an n-type semiconductor material. Alternatively, one or more intervening layers can be provided between the absorbing layer 160 and the n-type semiconductor material. In some embodiments, the absorbing layer 160 can be provided adjacent to the buffer layer 150. For example, the first surface 162 of the absorbing layer 160 can be provided on the second surface 154 of the buffer layer 150.

[0021]

[0029] Now referring to FIG. 3, in some embodiments, a photovoltaic device 200 includes an n-type semiconductor The photovoltaic device 200 may include a window layer 170 comprising a conductive material. Apart from the window layer 170, the photovoltaic device 200 may have a layer structure substantially similar to the photovoltaic device 100 (FIG. 1). The absorbing layer 160 may be formed adjacent to the window layer 170. The window layer 170 may have a first surface 172 substantially facing the energy side 102 of the photovoltaic device 200 and a second surface 174 substantially facing the opposite side 104 of the photovoltaic device 200. In some embodiments, the window layer 170 may be located between the absorbing layer 160 and the TCO layer 140. In one embodiment, the window layer 170 may be located between the absorbing layer 160 and the buffer layer 150. The window layer 170 may include any suitable material including, for example, cadmium sulfide, zinc sulfide, cadmium zinc sulfide, magnesium zinc oxide, or any combination thereof.

[0022]

[0030] Referring again to FIGS. 1 and 3, the photovoltaic devices 100, 200 can include a back contact 180 configured to mitigate unwanted changes in the dopant and provide an electrical contact to the absorption layer 160. The back contact 180 can have a first surface 182 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 184 substantially facing the opposite side 104 of the photovoltaic device 100. The thickness of the back contact 180 can be defined between the first surface 182 and the second surface 184. The thickness of the back contact 180 can be about 5 nm to about 220 nm, such as about 10 nm to about 200 nm in one embodiment, or about 10 nm to about 150 nm in one embodiment. The plurality of layers (including both) between the substrate 110 and the absorption layer 160 can be referred to as the absorber stack 109, 209. The back contact 180 can be disposed on the absorber stack 109, 209.

[0023]

[0031] In some embodiments, the back contact 180 may be provided adjacent to the absorption layer 160. For example, the first surface 182 of the back contact 180 may be provided on the second surface 164 of the absorption layer 160. In some embodiments, the back contact 180 can include a two-component or three-component combination of materials derived from Groups I, II, and VI. For example, the back contact 180 can include one or more layers containing zinc, cadmium, tellurium, or combinations thereof. In some embodiments, one or more layers of the back contact may be doped with a dopant, such as one or more Group I dopants. Alternatively or in addition, the back contact 180 can be a metal nitride material, such as MoN x (having an N composition in the range of 0 < x < 1), TiN y (having an N composition in the range of 0 < y < 1.1), WN z (having an N composition in the range of 0 < z < 1.1), TaN i (having an N composition in the range of 0 < i < 1.1), or ZrN jOne or more layers containing, such as, having an N composition where 0 < j < 1.1 can be included. Generally, the metal nitride material substantially does not contain oxidation, that is, the metal nitride material contains less than about 1% oxygen (atomic %), for example, less than about 0.5% oxygen. Alternatively or in addition, the back contact 180 can include one or more layers containing a metal oxynitride material, such as titanium oxynitride, tungsten oxynitride, zirconium oxynitride, or tantalum oxynitride. In some embodiments, the titanium oxynitride is TiO a N b which can be defined as having an O composition where 0 < a < 1.0 and an N2 composition where 0 < b < 1.1. In some embodiments, the tungsten oxynitride is WO c N d which can be defined as having an O composition where 0 < c < 1.0 and an N2 composition where 0 < d < 1.1.

[0024]

[0032] 1, 3 and 4 collectively, the back contact 180 can include a plurality of layers 202. The plurality of layers 202 of the back contact 180 can include a layer 210 including a metal oxynitride material. In some embodiments, the layer 210 can be comprised of a metal oxynitride material. In some embodiments, at least a portion of the metal oxynitride material can be comprised of a group IV, V, or VI transition metal, such as titanium or tungsten. The metal oxynitride material can be comprised of less than about 70% transition metal (atomic %), for example, in one embodiment, about 25% to about 60% of the metal oxynitride material can be the transition metal, or in another embodiment, about 30% to about 50% of the metal oxynitride material can be the transition metal. The metal oxynitride material can be comprised of less than about 50% oxygen (atomic %), for example, in one embodiment, about 5% to about 40% of the metal oxynitride material can be oxygen, or in another embodiment, about 10% to about 25% of the metal oxynitride material can be oxygen. The metal oxynitride material may be composed of less than about 50% nitrogen (atomic %), for example, in one embodiment, about 10% to about 45% of the metal oxynitride material may be nitrogen, or in another embodiment, about 25% to about 40% of the metal oxynitride material may be nitrogen.

[0025]

[0033] The layer 210 may have a first surface 212 that substantially faces the energy side 102 of the photovoltaic device 100, 200 and a second surface 214 that substantially faces the opposite side 104 of the photovoltaic device 100, 200. In some embodiments, the second surface 214 of the layer 210 may be the second surface 184 of the back contact 180. The thickness of the layer 210 may be defined between the first surface 212 and the second surface 214. The thickness of the layer 210 comprising the metal oxynitride material may be from about 1 nm to about 20 nm, such as from about 2 nm to about 20 nm in one embodiment, from about 3 nm to about 20 nm in another embodiment, from about 1 nm to about 5 nm in a further embodiment, or from about 5 nm to about 10 nm in a further embodiment.

[0026]

[0034] The layers 202 of the back contact 180 may include one or more layers containing zinc, cadmium, tellurium, or a combination between the layer 210 containing a metal oxynitride material and the first surface 182 of the back contact 180. For example, the layers 202 of the back contact 180 may include one or more layers containing zinc and tellurium between the layer 210 containing a metal oxynitride material and the first surface 182 of the back contact 180. In some embodiments, the layers 202 of the back contact 180 may include a first layer 220 and a second layer 230 disposed between the layer 210 containing a metal oxynitride material and the first surface 182 of the back contact 180. The first layer 220 of the back contact 180 may be disposed on the first surface 182 of the back contact 180. Accordingly, the first layer 220 may be disposed adjacent to the absorbing layer 160. In some embodiments, the first surface 182 of the back contact 180 may be a first surface 222 of a first layer 220. The first layer 220 may have a second surface 224 that faces substantially toward the opposite side 104 of the photovoltaic device 100. The first layer 220 of the back contact 180 may include a ternary component of cadmium, zinc, and tellurium. In some embodiments, the first layer 220 may consist of a ternary component of cadmium, zinc, and tellurium.

[0027]

[0035] The second layer 230 may be disposed between the layer 210 including the metal oxynitride material and the first layer 220 of the back contact 180. The thickness of the second layer 230 may be defined between a first surface 232 and a second surface 234. In some embodiments, the second layer 230 may be disposed adjacent to the first layer 220 and the layer 210 including the metal oxynitride material. Accordingly, the first surface 232 of the second layer 230 may be in contact with the second surface 224 of the first layer 220, and the second surface 234 of the second layer 230 may be in contact with the first surface 212 of the layer 210. The first layer 230 of the back contact 180 may include a binary of zinc and tellurium, which may be doped with a dopant (e.g., copper, silver, or both). In some embodiments, the second layer 230 may be comprised of a doped binary of zinc and tellurium.

[0028]

[0036] 1, 3 and 5 collectively, the back contact 180 can include a plurality of layers 204. The plurality of layers 204 of the back contact 180 can include a high purity metal layer 240 that includes a high concentration (atomic %) of a group IV, V or VI transition metal, for example, greater than about 80% of the high purity metal layer 240 can be composed of the selected transition metal in one embodiment, or greater than about 90% of the high purity metal layer 240 can be composed of the selected transition metal in one embodiment. In some embodiments, the high purity metal layer 240 can include a high concentration of titanium. In some examples, the high purity metal layer consists essentially of titanium. In some examples, the high purity metal layer consists essentially of titanium, tungsten, tantalum, zirconium, or combinations thereof.

[0029]

[0037] The high purity metal layer 240 may have a first surface 242 substantially facing the energy side 102 of the photovoltaic device 100, 200 and a second surface 244 substantially facing the opposite side 104 of the photovoltaic device 100, 200. A thickness of the high purity metal layer 240 may be defined between the first surface 242 and the second surface 244. The thickness of the high purity metal layer 240 may be from about 1 nm to about 5 nm. Alternatively or additionally, the thickness of the high purity metal layer 240 may be less than the thickness of the layer 210 comprising a metal oxynitride material. In some embodiments, the ratio of the thickness of the layer 210 comprising a metal oxynitride material to the thickness of the high purity metal layer 240 may be at least about 2:1.

[0030]

[0038] The high purity metal layer 240 may be located closer to the first surface 182 of the back contact 180 than the layer 210 comprising a metal oxynitride material. In some embodiments, the high purity metal layer 240 may be disposed between the layer 210 comprising a metal oxynitride material and one or more layers containing zinc and tellurium. For example, the high purity metal layer 240 may be adjacent to the layer 210 comprising a metal oxynitride material. Accordingly, the second surface 244 of the high purity metal layer 240 may contact the first surface 212 of the layer 210 comprising a metal oxynitride material. Alternatively or additionally, the high purity metal layer 240 may be adjacent to the second layer 230 of the back contact 180, i.e., the first surface 242 of the high purity metal layer 240 may contact the second surface 234 of the second layer 230.

[0031]

[0039] 1, 3 and 6 collectively, the back contact 180 can include a plurality of layers 206. The plurality of layers 206 of the back contact 180 can include a layer 250 including a metal nitride material having a metal concentration (atomic %) between about 30% and about 70% and a nitrogen concentration (atomic %) between about 70% and about 30%. Suitable metals include, but are not limited to, molybdenum, titanium, and tungsten. In some embodiments, the layer 250 can be made of a metal nitride. The layer 250 including a metal nitride can have a first surface 252 substantially facing the energy side 102 of the photovoltaic device 100, 200 and a second surface 254 substantially facing the opposite side 104 of the photovoltaic device 100, 200. The thickness of the layer 250 including a metal nitride can be defined between the first surface 252 and the second surface 254. The thickness of the metal nitride comprising layer 250 may be from about 2 nm to about 20 nm. Alternatively, or in addition, the thickness of the metal nitride comprising layer 250 may be greater than the thickness of the metal oxynitride comprising layer 210. In some embodiments, the ratio of the thickness of the metal nitride comprising layer 250 to the thickness of the metal oxynitride comprising layer 210 may be at least about 2:1, such as at least about 3:1 in some embodiments.

[0032]

[0040] The layer 250 including a metal nitride may be located closer to the second surface 184 of the back contact 180 than the layer 210 including a metal oxynitride material. In some embodiments, the layer 250 including a metal nitride may be adjacent to the layer 210 including a metal oxynitride material. Accordingly, the second surface 214 of the layer 210 including a metal oxynitride material may contact the first surface 252 of the layer 250 including a metal nitride. Alternatively or additionally, the second surface 254 of the layer 250 including a metal nitride may be the second surface 184 of the back contact 180.

[0033]

[0041] 1, 3 and 7 collectively, the back contact 180 can include a plurality of layers 208. The plurality of layers 208 of the back contact 180 can include a second layer 260 including a metal oxynitride material. The second layer 260 including a metal oxynitride material can be substantially similar to the layer 210 including a metal oxynitride material. In some embodiments, the layer 210 including a metal oxynitride material and the second layer 260 including a metal oxynitride material can be formed of different metals. In some embodiments, the layer 210 can be formed of TiO. a N b and the second layer 260 can include WO c N d Alternatively, layer 210 may include WO c N d and the second layer 260 can include TiO a N b may include.

[0034]

[0042] The second layer 260 comprising a metal oxynitride material may be located closer to the first surface 182 of the back contact 180 than the layer 210 comprising a metal oxynitride material. The second layer 260 comprising a metal oxynitride material may have a first surface 262 substantially facing the energy side 102 of the photovoltaic device 100, 200 and a second surface 264 substantially facing the opposite side 104 of the photovoltaic device 100, 200. In some embodiments, the layer 260 comprising a metal oxynitride material may be adjacent to the layer 210 comprising a metal oxynitride material. Accordingly, the second surface 264 of the second layer 260 comprising a metal oxynitride material may contact the layer 210 comprising a metal oxynitride material. Alternatively or additionally, the second layer 260 comprising a metal oxynitride material may be located between the layer 210 comprising a metal oxynitride material and one or more layers containing zinc and tellurium. In some embodiments, the second layer 260 including a metal oxynitride material may be adjacent to one or more layers containing zinc and tellurium. For example, the first surface 262 of the second layer 260 may contact the second surface 234 of the second layer 230 of the back contact 180.

[0035]

[0043] 1, 3 and 8 collectively, the back contact 180 can include a plurality of layers 209. The plurality of layers 209 of the back contact 180 can include a second layer 270 including a metal nitride material. The second layer 270 including a metal nitride material can have a first surface 272 substantially facing the energy side 102 of the photovoltaic device 100, 200 and a second surface 274 substantially facing the opposite side 104 of the photovoltaic device 100, 200. The second layer 270 including a metal nitride material can be substantially similar to the layer 250 including a metal nitride material. In some embodiments, the layer 250 including a metal nitride material and the second layer 270 including a metal nitride material can be formed of different metals. Alternatively, the layer 250 including a metal nitride material and the second layer 270 including a metal nitride material can be formed of the same material.

[0036]

[0044] The second layer 270 including a metal nitride material may be located closer to the first surface 182 of the back contact 180 than the layer 210 including a metal oxynitride material. In some embodiments, the second layer 270 including a metal nitride may be adjacent to the layer 210 including a metal oxynitride material. Accordingly, the second surface 274 of the second layer 270 including a metal oxynitride material may contact the first surface 212 of the layer 210 including a metal oxynitride material. Alternatively or additionally, the second layer 270 including a metal nitride material may be located between the layer 210 including a metal oxynitride material and one or more layers including zinc and tellurium. In some embodiments, the second layer 270 including a metal nitride material may be adjacent to one or more layers including zinc and tellurium. For example, the first surface 272 of the second layer 270 may contact the second surface 234 of the second layer 230 of the back contact 180.

[0037]

[0045] 1, 3 and 9 collectively, the photovoltaic device 100, 200 can include a conductive layer 190 configured to provide electrical contact with the absorber layer 160. The conductive layer 190 can have a first surface 192 substantially facing the energy side 102 of the photovoltaic device 100 and a second surface 194 substantially facing the opposite side 104 of the photovoltaic device 100. In some embodiments, the conductive layer 190 can be provided adjacent to the back contact 180. For example, the first surface 192 of the conductive layer 190 can be provided on the second surface 184 of the back contact 180. The conductive layer 190 can include any suitable conductive material, such as, for example, one or more layers of silver, nickel, copper, aluminum, titanium, palladium, chromium, molybdenum, gold, or alloys thereof. In some embodiments, the first surface 192 of the conductive layer 190 may be formed by a layer 276 comprising aluminum, such as a layer comprising at least about 90% aluminum (atomic %) (e.g., at least about 95% aluminum). Alternatively or additionally, the second surface 194 of the conductive layer 190 may be formed by a layer 278 comprising chromium.

[0038]

[0046] The photovoltaic device 100 may include a back support 196 configured to cooperate with the substrate 110 to form a housing for the photovoltaic device 100. The back support 196 may be disposed on the opposing side 102 of the photovoltaic device 100. For example, the back support 196 may be formed on the conductive layer 190. The back support 196 may include any suitable material including, for example, glass (e.g., soda-lime glass).

[0039]

[0047] The layers of the photovoltaic devices 100, 200 and devices described herein may be formed by a manufacturing process. The layers may be formed by one or more deposition processes, including, but not limited to, sputtering, vapor transport deposition (VTD), pulsed laser deposition (PLD), chemical vapor deposition (CVD), electrochemical deposition (ECD), evaporation, and / or atomic layer deposition (ALD).

[0040]

[0048] A method for fabricating a photovoltaic structure may include sequentially forming layers on a substrate. A TCO layer may be formed on a substrate layer, such as glass. Optionally, a buffer layer, a window layer, and / or an interface layer may be deposited on the substrate (including on a previously applied TCO layer). An absorber layer may be deposited on the substrate, including any interface layer, any n-type window layer, any buffer layer, the TCO layer, and the substrate. The multiple layers between (including) the substrate and the absorber layer may be referred to as an absorber stack. The absorber stack may be treated, for example, by heating, activation, and / or passivation, before applying the back contact layer. One or more layers are evaporated to form a conductive layer on the back contact layer. A back support may be formed on the conductive layer. During the fabrication process, scribe lines may be formed through selected layers.

[0041]

[0049] Precursor layers and processes can be applied to introduce dopants and / or achieve a particular final layer composition and structure. The deposition of a layer can include the deposition of one or more precursor layers that require an annealing or heating step after deposition to form the layer. As an example, in an embodiment in which an absorber layer is formed from one or more precursor layers, a first precursor layer, e.g., cadmium selenide (CdSe), is deposited on the substrate structure, followed by a second precursor layer, e.g., cadmium telluride (CdTe), deposited on the first precursor layer. The deposited precursor layers are then annealed to form the desired final layer composition, e.g., cadmium selenide tellurium alloy (CdSeTe). The annealing step causes interdiffusion of Se through the CdSeTe layer.

[0042]

[0050] An activation process may be performed on the deposited layer. As an example, an absorber activation step may be used to form an activated p-type absorber layer. The absorber activation step may include the introduction of a chlorine-containing material to the semiconductor material layer, e.g., cadmium chloride (CdCl2) as a bath liquid, spray liquid, or vapor, and associated annealing of the absorber stack at an elevated temperature. For example, if CdCl2 is used, it may be applied as an aqueous solution onto the absorber layer. Alternatively, the absorber layer may be annealed with CdCl2 by continuously flowing CdCl2 vapor over the surface of the absorber layer during the annealing step. Alternative chlorine doping materials may also be used, such as MnCl2, MgCl2, NH4Cl, ZnCl2, or TeCl4. Exemplary annealing may be performed at temperatures between about 350° C. and 475° C., for a total duration of 90 minutes or less, with a soak time of 60 minutes or less.

[0043]

[0051] Multi-step activation processes may be used, with each desired activation mechanism during the multi-step activation process, such as semiconductor grain growth, chlorine diffusion, interdiffusion of sulfur and / or selenium into the layer, using a different thermal activation energy to achieve the desired layer properties.

[0044]

[0052] In one example, an absorber activation step is followed by cleaning and passivation steps, followed by sequential deposition of multiple layers that form the back contact.

[0053] 4-8 and now turning to FIG. 10, an example method 900 for forming a back contact 180 is shown. An absorber stack is provided (901). Optionally, the absorber stack may be passivated (902). A number of layers (202, 204, 206, 208) that form the back contact 180 are deposited. In an example method for forming a back contact, a first layer 220 is deposited (220) on the absorber stack 109, 209. A second layer 230 is deposited on the first layer 220. Optionally, one or more selected layers 240, 260, 270 are deposited (940, 960, 970) on the second layer. The selected layer may include one or more of a high purity metal layer, a second metal oxynitride layer, or a second metal nitride layer. Material is deposited (910) to form a first metal oxynitride-containing layer 210. Layer 250, which may optionally include a metal nitride, is deposited on layer 210. Second surface 184 of back contact 180 corresponds to either second surface 254 of layer 250, if optional layer 250 is present, or second surface 214 of metal oxynitride-containing layer 210, if layer 250 and step 950 are omitted. The layer stack, including the layers that comprise the back contact, may be optionally heat treated. Scribe may be applied. One or more layers of conductive material are deposited (990) on second surface 184 of back contact 180 to form conductive layer 190.

[0045]

[0054] 11-12 show the test results of the example device compared to the comparative example. In the example process, a DC magnetron reactive sputtering process was used to form the metal nitride layers. The process pressure varied from 2-15 mTorr, the temperature ranged from room temperature to about 200°C, the N2% was about 14-70%, the process flow rate varied from 200-1000 sccm for N2, and the gas mixture was primarily Ar+N2 (metal nitride) or Ar+O2+N2 (metal oxynitride). The Al and Cr conductive layers were deposited using DC magnetron sputtering using Ar only.

[0046]

[0055] FIG. 11 shows increasing efficiency along the y-axis and eleven columns along the x-axis, each corresponding to a set of devices. The two leftmost columns are comparative examples. Two sets of comparative examples are shown: Comparative Example A and Comparative Example B. The comparative examples are ZnTe:Cu / MoN x The nine rightmost columns of comparative examples show a set of devices according to embodiments of the invention, with the thickness and nitrogen content of the metal nitride layer being compared between the different columns. In these example devices, MoN x The example devices were prepared using titanium nitride layers with thicknesses of 40, 60, 70, or 80 Angstroms (4.0, 6.0, 7.0, or 8.0 nm). The comparative example was a MoN layer having a thickness of 50 Angstroms (5.0 nm). x TiN layer x There was no layer. The example devices were prepared at selected points within the N2% range of 33% to 50%. The comparative examples were prepared within the N2% range of 33% to 50%. The example and comparative devices were prepared under similar deposition conditions, including temperature and pressure conditions.

[0047]

[0056] 12 shows increasing efficiency along the y-axis and grouping of devices along the x-axis. Comparative examples are in the center and left set, while example devices are shown in the right group. As shown, the example devices demonstrated higher efficiency than the comparative examples.

[0048]

[0057] In an embodiment of the invention, the back contact comprises a plurality of layers. In one example, the plurality of layers is a CdZnTe layer comprising an alloy of cadmium, tellurium, and zinc, and which may optionally contain dopants such as copper and / or silver, disposed adjacent to the absorber stack. a CdZnTe layer comprising zinc telluride doped with copper and / or silver, disposed adjacent to the CdZnTe layer; a metal oxynitride layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr), disposed adjacent to the ZnTe layer; and a metal nitride layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr), disposed adjacent to the metal oxynitride layer. A conductive layer may be disposed over the back contact and adjacent to the metal nitride layer. In an example device, the metal nitride comprises titanium nitride and the oxynitride comprises titanium oxynitride.

[0049]

[0058] In an embodiment of the invention, the back contact comprises a plurality of layers. In one example, the plurality of layers comprises a CdZnTe layer comprising an alloy of cadmium, tellurium and zinc, optionally doped with copper and / or silver, disposed adjacent to the absorber stack; a ZnTe layer comprising zinc telluride, optionally doped with copper and / or silver, disposed adjacent to the CdZnTe layer; a high purity metal layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr), disposed adjacent to the ZnTe layer; a backside layer comprising a metal oxynitride layer and / or a metal nitride layer, comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), or molybdenum (Mo), disposed adjacent to the high purity metal layer; and a conductive layer disposed adjacent to the backside layer. In an example device, the high purity metal layer comprises titanium and the backside layer comprises molybdenum and / or titanium.

[0050]

[0059] In an embodiment of the invention, the back contact comprises a plurality of layers. In one example, the plurality of layers comprises at least one surface layer comprising an alloy of tellurium and zinc, optionally alloyed with cadmium and optionally doped with copper and / or silver, disposed adjacent to the absorber stack; a high purity metal layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr), disposed on the at least one surface layer; a back layer comprising a metal oxynitride layer and / or a metal nitride layer, disposed on the high purity metal layer, comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), or molybdenum (Mo); and a conductive layer disposed adjacent to the back layer. In an example device, the high purity metal layer comprises titanium and the back layer comprises molybdenum and / or titanium.

[0051]

[0060] In an embodiment of the invention, the back contact comprises a plurality of layers. In one example, the plurality of layers comprises a CdZnTe layer comprising an alloy of cadmium, tellurium, and zinc, optionally doped with copper and / or silver, disposed on the absorber stack; a ZnTe layer comprising zinc telluride, optionally doped with copper and / or silver, disposed on the CdZnTe layer; a metal oxynitride layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), and / or chromium (Cr), disposed on the ZnTe layer; a metal nitride layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), and / or chromium (Cr) and disposed adjacent to the metal oxynitride layer; a second metal nitride layer comprising at least one transition metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), zirconium (Zr), and / or molybdenum (Mo) and disposed between and adjacent to the metal oxynitride layer and the ZnTe layer. A conductive layer may be disposed on the metal nitride layer of the back contact. In an example, the conductive layer may include multiple layers comprising aluminum and chromium. In an example device, the metal nitride comprises titanium nitride, the second metal nitride comprises titanium nitride, and the oxynitride comprises titanium oxynitride.

[0052]

[0061] In an embodiment of the invention, the back contact comprises a plurality of layers. In one example, the plurality of layers comprises at least one front layer comprising an alloy of tellurium and zinc, optionally alloyed with cadmium and optionally doped with copper and / or silver, disposed on an absorber stack comprising an absorber layer having cadmium, tellurium, and selenium; and a back layer comprising a metal oxynitride layer and / or a metal nitride layer, disposed on the at least one front layer comprising at least one transition metal from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), or zirconium (Zr). A conductive layer may be disposed on the back layer of the back contact. In an example device, the back layer comprises titanium nitride and / or titanium oxynitride, and the device does not comprise molybdenum.

[0053]

[0062] In an example method, at least one layer of the back contact is deposited by vapor transport deposition (VTD) onto a substrate stack transported along a deposition path: A precursor material is heated to form a vapor that is guided to the substrate by a carrier gas.

[0054]

[0063] In an example method, the back contact is formed by a VTD process and sputtering. In one embodiment, an alloy of cadmium, tellurium, and zinc is deposited by VTD and the nitride and / or oxynitride layer is deposited by reactive magnetron sputtering.

[0055]

[0064] In certain examples, the metal of the metal nitride material includes molybdenum, titanium, tungsten, tantalum, and / or zirconium.

[0065] In one example, the metal of the metal nitride material includes at least one of titanium, tungsten, tantalum, or zirconium.

[0056]

[0066] In an embodiment of the invention, the absorber stack includes a p-type absorber layer comprising cadmium and tellurium.

[0067] In one example, the absorber stack includes a p-type absorber layer that includes cadmium, tellurium, and selenium.

[0057]

[0068] In one example, the back contact is between and adjacent to the absorber stack and the conductive layer.

[0069] In one example, the conductive layer includes at least one layer including aluminum adjacent to at least one layer including chromium.

[0058]

[0070] In one example, the metal oxynitride material includes 30% to 70% of a Group IV transition metal, a Group V transition metal, or a Group VI transition metal, and the metal oxynitride material includes 1% to 15% oxygen.

[0071] In one example, the metal oxynitride material comprises 30%-50% nitrogen, 2%-8% oxygen, and 42%-68% of at least one metal selected from the group consisting of titanium (Ti), tungsten (W), tantalum (Ta), and zirconium (Zr).

[0059]

[0072] In some examples, the photovoltaic device does not include molybdenum (Mo).

[0073] In some examples, the metal oxynitride layer consists essentially of titanium oxynitride. In some embodiments, the layer including titanium oxynitride material includes less than 25% oxygen. In some embodiments, the layer including titanium oxynitride material includes between 2% and 15% oxygen. In some embodiments, the layer including titanium oxynitride material has a thickness in the range of between 0.5 nm and 5.0 nm.

[0060]

[0074] In some examples, the metal oxynitride layer consists essentially of tungsten oxynitride. In some embodiments, the layer including the tungsten oxynitride material includes less than 25% oxygen. In some embodiments, the layer including the tungsten oxynitride material includes between 1% and 20% oxygen. In some embodiments, the layer including the tungsten oxynitride material has a thickness in the range of 0.5 nm to 5.0 nm.

[0061]

[0075] In one example, the metal oxynitride layer consists essentially of tantalum oxynitride.

[0076] In one example, the metal oxynitride layer consists essentially of zirconium oxynitride.

[0077] In one example, the back contact includes a first metal oxynitride layer adjacent to a second metal oxynitride layer, the first metal oxynitride layer including tungsten and the second metal oxynitride layer including titanium.

[0062]

[0078] In one example, the metal oxynitride layer contains between 1% and 50% oxygen.

[0079] In some instances, the metal oxynitride material contains less than 50% nitrogen.

[0080] In some examples, the back contact comprises a high purity metal layer. In some embodiments, the high purity metal layer has a thickness between 1 nm and 5 nm. In some embodiments, the high purity metal layer comprises a composition of 85% to 100% or 95% to 100% of a single metal element. In some embodiments, the high purity metal layer comprises a composition of 85% to 100% or 95% to 100% of an alloy of metal elements. In some embodiments, the high purity metal layer consists essentially of titanium.

[0063]

[0081] In one example, the layer including the metal oxynitride material has a thickness between 1 nm and 20 nm and the back contact has a thickness between 5 nm and 220 nm.

[0082] In another embodiment, a photovoltaic device comprises an absorber stack; a conductive layer having a surface formed by a layer comprising aluminum; and a back contact having a first surface, a second surface, and a thickness defined between the back contact first surface and the back contact second surface, where the back contact first surface is adjacent a p-type absorber layer of the absorber stack; the back contact second surface is in contact with a surface of the conductive layer; the back contact comprises a layer comprising a metal oxynitride material and one or more layers containing zinc, cadmium, tellurium, or any combination thereof located between the layer comprising the metal oxynitride material and the back contact first surface.

[0064]

[0083] In some embodiments, the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal.

[0084] In some embodiments, the metal nitride and / or metal oxynitride materials include Group IV transition metals, Group V transition metals, or Group VI transition metals excluding molybdenum.

[0065]

[0085] In some embodiments, the metal oxynitride material contains less than about 70% Group IV transition metals, Group V transition metals, or Group VI transition metals.

[0086] In some embodiments, the metal oxynitride material is titanium oxynitride.

[0066]

[0087] In some embodiments, the metal oxynitride material is tungsten oxynitride.

[0088] In some embodiments, the metal oxynitride material is tantalum oxynitride.

[0089] In some embodiments, the metal oxynitride material is zirconium oxynitride.

[0067]

[0090] In some embodiments, the metal oxynitride material contains less than 50% oxygen.

[0091] In some embodiments, the metal oxynitride material contains less than 50% nitrogen.

[0092] In some embodiments, the layer comprising a metal oxynitride material has a thickness between 1 nm and 20 nm.

[0068]

[0093] In some embodiments, the back contact has a thickness between 5 nm and 220 nm.

[0094] In some embodiments, the one or more layers containing zinc, cadmium, tellurium, or any combination thereof include a first layer comprising ternary components of cadmium, zinc, and tellurium, and a second layer comprising binary components of zinc and tellurium; the first layer of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof is located closer to the first surface of the back contact than the second layer of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof.

[0069]

[0095] In one example, the zinc and tellurium binary is doped with copper, silver, or both.

[0096] In some embodiments, the back contact comprises a high purity metal layer disposed between a layer comprising a metal oxynitride material and one or more layers containing zinc, cadmium, tellurium, or any combination thereof; the high purity metal layer comprises at least 80% metal.

[0070]

[0097] In one example, the metal of the high purity metal layer is titanium.

[0098] In some embodiments, the thickness of the high purity metal layer is less than the thickness of the layer comprising a metal oxynitride material.

[0071]

[0099] In some embodiments, the back contact includes a layer including a metal nitride material; the layer including the metal nitride material is located closer to the second surface of the back contact than the layer including the metal oxynitride material; and the metal nitride material has a concentration of metal between 30% and 70% and a concentration of nitrogen between 70% and 30%.

[0072]

[0100] In some embodiments, the metal of the metal nitride material is selected from the group consisting of molybdenum, titanium, tantalum, and the like. The metal is tungsten, tantalum, or zirconium.

[0101] In some embodiments, the thickness of the layer including the metal nitride material and the metal oxynitride material The ratio of the thickness of the layer containing the

[0073]

[0102] In some embodiments, the second surface of the back contact comprises a metal nitride material. It is formed by layers.

[0103] In some embodiments, the back contact includes a second layer comprising a metal nitride material. a second layer comprising a metal nitride material adjacent to the layer comprising a metal oxynitride material.

[0074]

[0104] In some embodiments, the back contact comprises a second layer comprising a metal oxynitride material. the second layer comprising a metal oxynitride material is located between the layer comprising the metal oxynitride material and the one or more layers containing zinc, cadmium, tellurium, or any combination thereof.

[0075]

[0105] In some embodiments, a layer including a metal oxynitride material and a metal oxynitride material and the second layer including the first metal oxynitride are formed from a different metal oxynitride.

[0106] In some embodiments, the conductive layer is a second layer formed by a layer comprising chromium. The surface of the

[0076]

[0107] In some embodiments, the photovoltaic device comprises cadmium and tellurium. It includes an absorbent layer, and a first surface of the back contact is adjacent to the absorbent layer.

[0108] In another embodiment, the photovoltaic device comprises an absorber layer comprising cadmium and tellurium. and a back contact having a first surface, a second surface, and a thickness defined between the back contact first surface and the back contact second surface, wherein the back contact first surface contacts the absorbing layer, and the back contact includes a layer comprising a metal oxynitride material and one or more layers containing zinc, cadmium, tellurium, or any combination thereof located between the layer comprising the metal oxynitride material and the back contact first surface.

[0077]

[0109] In some embodiments, the photovoltaic device is provided with a layer comprising aluminum. The back contact further comprises a conductive layer having a surface formed thereon, the second surface of the back contact contacting the surface of the conductive layer.

[0078]

[0110]

[0013] Here, embodiments of the present disclosure provide a backplane comprising one or more layers of a metal oxynitride. It should be understood that the back contacts provided herein exhibit low electrical resistivity, high work function, and thermal stability relative to high ohmic contacts. Accordingly, the back contacts described herein can form low barrier contacts to absorber films including CdTe. Back contacts including one or more layers of metal oxynitrides provided herein have been included in photovoltaic devices that have demonstrated improved solar-to-electrical conversion efficiency compared to substantially similar photovoltaic devices that have excluded one or more layers of metal oxynitrides from the back contact of the photovoltaic device. The higher efficiency was associated with improved photovoltaic device parameters (e.g., higher short circuit current, higher fill factor, higher open circuit voltage, lower open circuit resistivity).

[0079]

[0111] According to embodiments provided herein, a photovoltaic device includes a conductive layer and a barrier layer. The back contact may include a back contact. The conductive layer may have a surface formed by a layer comprising aluminum. The back contact may have a first surface, a second surface, and a thickness defined between the first surface of the back contact and the second surface of the back contact. The second surface of the back contact may be in contact with the surface of the conductive layer. The back contact may include a layer comprising a metal oxynitride material and one or more layers comprising zinc, cadmium, tellurium, or any combination thereof. The one or more layers comprising zinc, cadmium, tellurium, or any combination thereof may be located between the layer comprising a metal oxynitride material and the first surface of the back contact.

[0080]

[0112] According to embodiments provided herein, a photovoltaic device includes an absorber layer and a barrier layer. The back contact may include a back contact. The absorbing layer may include cadmium and tellurium. The back contact may have a first surface, a second surface, and a thickness defined between the first surface of the back contact and the second surface of the back contact. The first surface of the back contact may be in contact with the absorbing layer. The back contact may include a layer including a metal oxynitride material and one or more layers including zinc, cadmium, tellurium, or any combination thereof. The one or more layers including zinc, cadmium, tellurium, or any combination thereof may be located between the layer including the metal oxynitride material and the first surface of the back contact.

[0081]

[0113] The terms "substantially" and "about" are used herein to denote any quantitative comparison, These terms may be used to express the inherent degree of uncertainty that may result from a value, measurement, or other representation. These terms are also used herein to express the degree to which a quantitative expression may vary from a stated standard without causing a change in the basic functionality of the subject matter in question.

[0082]

[0114] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter. [Mode of the invention] [1] a conductive layer having a surface formed by a layer including aluminum; and Back Contact 1. A photovoltaic device comprising: the back contact has a first surface and a second surface and has a thickness defined between the back contact first surface and the back contact second surface; a second surface of the back contact contacts a surface of the conductive layer; and The back contact is a layer comprising a metal oxynitride material; and one or more layers containing zinc, cadmium, tellurium, or any combination thereof, located between the layer comprising the metal oxynitride material and the first surface of the back contact; Including, Photovoltaic devices. [2] 2. The photovoltaic device of claim 1, wherein the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal. [3] 3. The photovoltaic device of claim 2, wherein the metal oxynitride material comprises less than about 70% Group IV transition metal, Group V transition metal, or Group VI transition metal. [4] 4. The photovoltaic device of claim 3, wherein the metal oxynitride material is titanium oxynitride. [5] 4. The photovoltaic device of claim 3, wherein the metal oxynitride material is tungsten oxynitride. [6] 4. The photovoltaic device of claim 3, wherein the metal oxynitride material is tantalum oxynitride. [7] 4. The photovoltaic device of claim 3, wherein the metal oxynitride material is zirconium oxynitride. [8] 2. The photovoltaic device of claim 1, wherein the metal oxynitride material contains less than 50% oxygen. [9] 2. The photovoltaic device of claim 1, wherein the metal oxynitride material contains less than 50% nitrogen.

[10] 2. The photovoltaic device of claim 1, wherein the layer comprising a metal oxynitride material has a thickness of 1 nm to 20 nm.

[11] 2. The photovoltaic device of claim 1, wherein the back contact has a thickness of 5 nm to 220 nm.

[12] the one or more layers containing zinc, cadmium, tellurium, or any combination thereof include a first layer containing ternary components of cadmium, zinc, and tellurium, and a second layer containing binary components of zinc and tellurium; 2. The photovoltaic device of claim 1, wherein the first of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof is located closer to the first surface of the back contact than the second of the one or more layers containing zinc, cadmium, tellurium, or any combination thereof.

[13] 13. The photovoltaic device of claim 12, wherein the zinc and tellurium binary is doped with copper, silver, or both.

[14] the back contact comprises a high purity metal layer disposed between the layer comprising the metal oxynitride material and the layer or layers containing zinc, cadmium, tellurium, or any combination thereof; The high purity metal layer comprises at least 80% metal. 2. The photovoltaic device according to claim 1.

[15] 15. The photovoltaic device of claim 14, wherein the metal of the high purity metal layer is titanium.

[16] 15. The photovoltaic device of claim 14, wherein the high purity metal layer has a thickness less than a thickness of the layer comprising the metal oxynitride material.

[17] the back contact comprises a layer comprising a metal nitride material; the layer comprising a metal nitride material is closer to a second surface of the back contact than the layer comprising a metal oxynitride material; The metal nitride material has a metal concentration of 30% to 70% and a nitrogen concentration of 70% to 30%. 2. The photovoltaic device according to claim 1.

[18] 18. The photovoltaic device of claim 17, wherein the metal of the metal nitride material is molybdenum, titanium, tungsten, tantalum, or zirconium.

[19] 18. The photovoltaic device of claim 17, wherein the ratio of a thickness of the layer comprising the metal nitride material to a thickness of the layer comprising the metal oxynitride material is at least 2:1.

[20] 18. The photovoltaic device of claim 17, wherein the second surface of the back contact is formed by a layer comprising the metal nitride material. [twenty one] the back contact comprises a second layer comprising a metal nitride material; a second layer comprising the metal nitride material adjacent to the layer comprising the metal oxynitride material; 18. The photovoltaic device according to claim 17. [twenty two] the back contact comprises a second layer comprising a metal oxynitride material; a second layer comprising the metal oxynitride material is located between the layer comprising the metal oxynitride material and the layer or layers containing zinc, cadmium, tellurium, or any combination thereof; 2. The photovoltaic device according to claim 1. [twenty three] 23. The photovoltaic device of claim 22, wherein the layer comprising a metal oxynitride material and the second layer comprising a metal oxynitride material are formed from different metal oxynitrides. [twenty four] 2. The photovoltaic device of claim 1, wherein the conductive layer has a second surface formed by a layer comprising chromium. [twenty five] 2. The photovoltaic device of claim 1, further comprising an absorber layer comprising cadmium and tellurium, the first surface of the back contact being adjacent to the absorber layer.

[26] an absorbing layer comprising cadmium and tellurium; and Back Contact 1. A photovoltaic device comprising: the back contact has a first surface and a second surface and has a thickness defined between the back contact first surface and the back contact second surface; a first surface of the back contact in contact with the absorbing layer; and The back contact is a layer comprising a metal oxynitride material; and one or more layers containing zinc, cadmium, tellurium, or any combination thereof, located between the layer comprising the metal oxynitride material and the first surface of the back contact; Including, Photovoltaic devices.

[27] 27. The photovoltaic device of claim 26, comprising a conductive layer having a surface formed by a layer comprising aluminum, the second surface of the back contact contacting a surface of the conductive layer.

[28] 28. The photovoltaic device of any one of 1 and 26-27, wherein the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal.

[29] 29. The photovoltaic device of claim 28, wherein the metal oxynitride material comprises less than about 70% Group IV transition metal, Group V transition metal, or Group VI transition metal.

[30] 30. The photovoltaic device of any one of 1 and 26-29, wherein the metal oxynitride material is titanium oxynitride.

[31] 30. The photovoltaic device of any one of 1 and 26-29, wherein the metal oxynitride material is tungsten oxynitride.

[32] 30. The photovoltaic device of any one of 1 and 26-29, wherein the metal oxynitride material is tantalum oxynitride.

[33] 30. The photovoltaic device of any one of 1 and 26-29, wherein the metal oxynitride material is zirconium oxynitride.

[34] 34. The photovoltaic device of any one of claims 1 and 26-33, wherein the metal oxynitride material contains less than 50% oxygen.

[35] 35. The photovoltaic device of any one of claims 1 and 26-34, wherein the metal oxynitride material contains less than 50% nitrogen.

[36] 36. The photovoltaic device of any one of claims 1 and 26 to 35, wherein the layer comprising a metal oxynitride material has a thickness of 1 nm to 20 nm.

[37] 37. The photovoltaic device of any one of claims 1 and 26 to 36, wherein the back contact has a thickness of from 5 nm to 220 nm.

[38] the one or more layers containing zinc, cadmium, tellurium, or any combination thereof include a first layer containing ternary components of cadmium, zinc, and tellurium, and a second layer containing binary components of zinc and tellurium; the first layer of one or more layers containing zinc, cadmium, tellurium, or any combination thereof is located closer to the first surface of the back contact than the second layer of one or more layers containing zinc, cadmium, tellurium, or any combination thereof; 40. The photovoltaic device according to any one of claims 1 and 26 to 37.

[39] 39. The photovoltaic device of claim 38, wherein the zinc and tellurium binary is doped with copper, silver, or both.

[40] the back contact comprises a high purity metal layer disposed between the layer comprising the metal oxynitride material and the layer or layers containing zinc, cadmium, tellurium, or any combination thereof; The high purity metal layer comprises at least 80% metal. 40. The photovoltaic device according to any one of claims 1 and 26 to 39.

[41] 41. The photovoltaic device of claim 40, wherein the metal of the high purity metal layer is titanium.

[42] 42. The photovoltaic device of claim 40 or 41, wherein the high purity metal layer has a thickness less than a thickness of the layer comprising the metal oxynitride material.

[43] the back contact comprises a layer comprising a metal nitride material; the layer comprising a metal nitride material is closer to a second surface of the back contact than the layer comprising a metal oxynitride material; The metal nitride material has a metal concentration of 30% to 70% and a nitrogen concentration of 70% to 30%. 43. The photovoltaic device according to any one of claims 1 and 26 to 42.

[44] 44. The photovoltaic device of claim 43, wherein the metal of the metal nitride material is molybdenum, titanium, tungsten, tantalum, or zirconium.

[45] 45. The photovoltaic device of any one of claims 43 to 44, wherein the ratio of a thickness of the layer comprising the metal nitride material to a thickness of the layer comprising the metal oxynitride material is at least 2:1.

[46] 46. ​​The photovoltaic device of any one of claims 43 to 45, wherein the second surface of the back contact is formed by a layer comprising the metal nitride material.

[47] the back contact comprises a second layer comprising a metal nitride material; a second layer comprising the metal nitride material adjacent to the layer comprising the metal oxynitride material; 46. ​​The photovoltaic device according to claim 46.

[48] the back contact comprises a second layer comprising a metal oxynitride material; a second layer comprising the metal oxynitride material is located between the layer comprising the metal oxynitride material and the layer or layers containing zinc, cadmium, tellurium, or any combination thereof; 33 to 47. A photovoltaic device according to any one of claims 33 to 47.

[49] 49. The photovoltaic device of claim 48, wherein the layer comprising a metal oxynitride material and the second layer comprising a metal oxynitride material are formed from different metals.

[50] 50. The photovoltaic device of any one of claims 1 and 27 to 49, wherein the conductive layer has a second surface formed by a layer comprising chromium.

[51] 51. The photovoltaic device of any one of claims 1 and 28-50, comprising an absorber layer comprising cadmium and tellurium, and a first surface of the back contact adjacent to the absorber layer.

[52] 52. The photovoltaic device of any one of claims 26 to 51, wherein the absorbing layer comprises selenium.

Claims

1. an absorbing layer comprising cadmium and tellurium; and Back Contact 1. A photovoltaic device comprising: the back contact has a first surface and a second surface and has a thickness defined between the back contact first surface and the back contact second surface; a first surface of the back contact in contact with the absorbing layer; and The back contact is a layer comprising a metal oxynitride material; at least one layer containing zinc and tellurium; and a high purity metal layer comprising at least 80% metal disposed between the layer comprising a metal oxynitride material and the at least one layer comprising zinc and tellurium; wherein the at least one layer containing zinc and tellurium is located between the layer containing the metal oxynitride material and the first surface of the back contact, and the metal oxynitride material contains less than 50% nitrogen. Photovoltaic devices.

2. 10. The photovoltaic device of claim 1 comprising a conductive layer having a surface formed by a layer comprising aluminum, the second surface of the back contact contacting the surface of the conductive layer.

3. The photovoltaic device of claim 1 or 2, wherein the metal oxynitride material comprises a Group IV transition metal, a Group V transition metal, or a Group VI transition metal.

4. 4. The photovoltaic device of claim 3, wherein the metal oxynitride material comprises less than 70% Group IV transition metals, Group V transition metals, or Group VI transition metals.

5. The photovoltaic device of any one of claims 1 to 4, wherein the metal oxynitride material is titanium oxynitride.

6. The photovoltaic device of any one of claims 1 to 4, wherein the metal oxynitride material is tungsten oxynitride.

7. The photovoltaic device of any one of claims 1 to 4, wherein the metal oxynitride material is tantalum oxynitride.

8. The photovoltaic device of any one of claims 1 to 4, wherein the metal oxynitride material is zirconium oxynitride.

9. The photovoltaic device of any one of claims 1 to 8, wherein the metal oxynitride material contains less than 50% oxygen.

10. an absorbing layer comprising cadmium and tellurium; and Back Contact 1. A photovoltaic device comprising: the back contact has a first surface and a second surface and has a thickness defined between the back contact first surface and the back contact second surface; a first surface of the back contact in contact with the absorbing layer; and The back contact is a layer comprising a metal oxynitride material; at least one layer containing zinc and tellurium; and A second layer comprising a metal oxynitride material. wherein the at least one layer containing zinc and tellurium is located between the layer comprising the metal oxynitride material and a first surface of the back contact, and the metal oxynitride material comprises less than 50% nitrogen, and a second layer comprising the metal oxynitride material is located between the layer comprising the metal oxynitride material and the at least one layer containing zinc and tellurium. Photovoltaic devices.

11. The photovoltaic device of any one of claims 1 to 10, wherein the layer comprising a metal oxynitride material has a thickness of 1 nm to 20 nm.

12. The photovoltaic device of any one of claims 1 to 11, wherein the back contact has a thickness of from 5 nm to 220 nm.

13. The at least one layer containing zinc and tellurium includes a first layer containing three components of cadmium, zinc, and tellurium, and a second layer containing two components of zinc and tellurium; the first layer being closer to the first surface of the back contact than the second layer; A photovoltaic device according to any one of the preceding claims.

14. The photovoltaic device of claim 13 , wherein the second layer comprises zinc telluride doped with copper, silver, or both.

15. the back contact comprises a high purity metal layer disposed between the layer comprising the metal oxynitride material and the at least one layer containing zinc and tellurium; The high purity metal layer comprises at least 80% metal. The photovoltaic device of claim 10.

16. the back contact comprises a second layer comprising a metal oxynitride material; a second layer comprising the metal oxynitride material located between the layer comprising the metal oxynitride material and the at least one layer containing zinc and tellurium; The photovoltaic device of claim 1 .

17. The photovoltaic device of any one of claims 1 to 16, wherein the absorbing layer comprises selenium.

18. 11. The photovoltaic device of claim 1 or 10, wherein the photovoltaic device comprises a layer comprising at least one of tin oxide, fluorine doped tin oxide, indium tin oxide, and cadmium stannate.

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