Patent Description:
Embodiments described herein relate to solar cells, and more particularly to interconnect structures for perovskite solar cell modules.

Photovoltaic cells, also referred to solar cells, are devices that convert radiant photo energy into electrical energy. Multiple solar cells may be integrated into a group to constitute a solar panel, or module, in which the solar cells are usually connected in series creating an additive voltage.

Monocrystalline solar cells are dominant in the current solar cell industry, offering some of the highest efficiencies and lifetimes. However, the cost associated monocrystalline solar cells is a driving factor in the development of alternative solar cell technologies. One class of development is thin-film solar cells. Thin-film solar cells are attractive due to the potential to implement economical in-line processes of deposition and patterning sequences. As thin-film solar cells continue to improve in efficiency they may be candidates to displace currently adopted monocrystalline solar cells at a reduced cost, or create new solar cell markets. Furthermore, some thin-film solar cells can be flexible with potential applications on curved surfaces, mobile devices, or other components. Two such emerging thin-film technologies include cadmium telluride (CdTe) and copper indium gallium selenide (CIGS). More recently perovskite solar cells have gained attention with a rapid surge in reported cell efficiency. <CIT> describes a perovskite solar cell module capable of preventing a solar cell from being damaged by a high-power laser, and a manufacturing method thereof. <CIT> describes a perovskite solar cell module comprises: a transparent substrate partitioned into a first cell region and a second cell region; and first and second perovskite solar cells which are respectively formed on the first and second cell regions on the transparent substrate. The first and second perovskite solar cells comprise:
a transparent electrode; an absorption layer consisting of a perovskite material; a metal electrode to which holes are injected from the absorption layer; and a hole conductive layer, interposed between the absorption layer and the metal electrode, for transporting the holes to the metal electrode. The metal electrode comprises a connection part, connected to the transparent electrode included in the second perovskite solar cell, for electrically connecting the first and second perovskite solar cells.

The hole conductive layer comprises an insulation part, interposed between the absorption layer and the connection part, for electrically insulating the absorption layer from the connection part. <NPL> describes common device and module architectures, scalable deposition methods and progress in the scalable deposition of perovskite and charge-transport layers.

<NPL>, describes the main cell-to-module efficiency loss mechanisms and discusses the various strategies explored in academia and industry to reduce the efficiency gap: new transparent conductive oxides, hybrid modularization approaches and the use of wide-bandgap solar absorbers in the <NUM>-<NUM> eV range.

Aspects of the invention are as set out in the appended claims. Thin-film solar cell modules and serial cell-to-cell interconnect structures and methods fabrication are described. In particular examples describe structures and fabrication sequences that may protect the integrity of the subcell absorber material, such as a metal-halide perovskite, from decompostion and allow the integration of adjacent metal layers.

In an example a solar cell module includes a bottom electrode layer with a plurality of first patterned line openings, a subcell layer over the bottom electrode layer, the subcell layer including a plurality of second patterned line openings, a conformal transport layer over subcell layer and laterally surrounding an outside perimeter the subcell layer, and a patterned top electrode layer over the conformal transport layer. The conformal transport layer may encapsulate the subcell layer to prevent perovskite-metal contact and perovskite decomposition. In an embodiment, a non-metallic intermediate layer, which may be an insulator layer, is located between the conformal transport layer and the subcell layer, with the non-metallic intermediate layer laterally surrounding the outside perimeter of the subcell layer. In such a configuration the conformal transport layer may also surround an outside perimeter of the non-metallic intermediate layer.

In an embodiment, a solar cell interconnect includes a bottom electrode layer on a substrate, a first patterned line opening P1 in the bottom electrode layer, a subcell layer over the bottom electrode layer and within the first patterned line opening P1, a second patterned line opening P2 in the subcell layer, a non-metallic intermediate layer along sidewalls of the second patterned line opening P2, a conformal transport layer over the subcell layer, on the non-metallic intermediate layer within the second patterned line opening P2 and over the bottom electrode layer within the second patterned line opening P1, and a top electrode layer over the conformal transport layer and on the conformal transport layer within the second patterned line opening P2. A third patterned line opening P3 is formed through at least the top electrode layer.

In an example, a solar cell interconnect includes a bottom electrode layer, a first patterned line opening P1 in the bottom electrode layer, a subcell layer over the bottom electrode layer, a second patterned line opening P2 in the subcell layer, a conductive plug within P2, a conformal transport layer over the subcell layer and the conductive plug, a top electrode layer over the conformal transport layer, and a third patterned line opening P3 in the top electrode layer. The conductive plug may substantially fill P2 in an embodiment. In another embodiment, a non-metallic intermediate layer may be formed along a single sidewall of P2. More specifically, the non-metallic intermediate layer may be formed along a single sidewall of P1 that is shared with P1.

In an example, a solar cell interconnect includes a bottom electrode layer, a first patterned line opening P1 in the bottom electrode layer, a subcell layer over the bottom electrode layer, a conformal transport layer over the subcell layer, a top electrode layer over the conformal transport layer, and a second patterned line opening P2 through the top electrode layer, the conformal transport layer and the subcell layer. A conductive plug is located within the second patterned line opening. In another embodiment, a non-metallic intermediate layer may be formed along one or more sidewalls of P2.

The top electrode layer in accordance with embodiments may include a metal layer. The conformal transport layer may provide a physical barrier between the subcell layer and top electrode layer. Additionally, various configurations are possible for forming a third patterned line opening P3 in the top electrode layer to avoid metal contact with the subcell layer. In some embodiments the top electrode layer may be patterned with a shadow mask. In some embodiments the top electrode layer and underlying layers may be patterned by scribing through the top electrode layer and into underlying layers. The P3 scribe may be filled with a non-electrically conductive. The P3 scribe may possibly extend into the non-metallic intermediate layer. In some embodiments P1 and P2 do not overlap. In other embodiments, P2 overlaps P1.

Embodiments describe interconnect structure for thin film solar cell modules, and in particular metal-halide perovskite-based solar cells. In various aspects, embodiments describe interconnect structures that allow for economical in-line processing sequences, and the use of a metal rear electrode, which can provide rear reflection for light harvesting, low cost, and high conductivity. It has been observed that the performance and stability of metal-halide perovskite-based solar cells are highly susceptible to metal induced degradation caused by halide-metal interactions. Specifically, metal electrodes may react with halides in the perovskite and act as a sink for halides and corrosion of the metal electrode, degrading conductivity. In accordance with various embodiments, solar cell module interconnect structures are described in which a conformal transport layer may also function as a barrier layer to prevent perovskite-metal contact and the damage of the subcell structure. Furthermore, the interconnect structures in accordance with embodiments may act to prevent the ingress of moisture and oxygen and egress of volatile organic components, which may significantly increase the stability of metal-halide perovskite-based solar cells.

In various embodiments, description is made with reference to figures. However, certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions and processes, etc., in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the embodiments. Reference throughout this specification to "one embodiment" means that a particular feature, structure, configuration, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrase "in one embodiment" in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

The terms "over", "to", "between", and "on" as used herein may refer to a relative position of one layer with respect to other layers. One layer "over", or "on" another layer or in "contact" with another layer may be directly in contact with the other layer or may have one or more intervening layers. One layer "between" layers may be directly in contact with the layers or may have one or more intervening layers.

Referring now to <FIG> a schematic top view illustration is provided of a solar cell module. As shown, the module <NUM> includes a plurality of cells <NUM> (also referred to as solar cells) coupled in series with interconnects <NUM>, with the front of one cell connected to the rear of the next cell so that their voltages (V<NUM>. The plurality of cells <NUM> may be arranged into one or more subsets <NUM> (e.g. strings) coupled in parallel, which may have the effect of decreasing total module voltage.

A thin-film solar cell <NUM> commonly includes a subcell between two electrodes, at least one of which being transparent. As described in more detail with regard to <FIG> and <FIG>, the subcell may commonly include an absorber layer and one or more transport layers (e.g. hole transport, electron transport). The subcells in accordance with embodiments can include a single junction, or a multiple junction structure with multiple absorber layers. In order to minimize loss due limited conductivity of the transparent electrode, the module is divided into the plurality of smaller cells <NUM> which are electrically connected in series. The serial interconnect methodologies in accordance with embodiments may generally include a plurality of patterned line openings (P1, P2, P3, etc.) to form interconnects <NUM>, such as a first patterned line opening P1 through a bottom electrode, a second patterned line opening P2 through the subcell which includes the absorber and transport layer(s), and a third patterned line opening P3 through a top/rear electrode to electrically isolate adjacent cells <NUM>.

Referring now to <FIG>, schematic top view illustrations are provided of a method of fabricating a solar cell module <NUM> in accordance with embodiments. As shown in <FIG>, the sequence may begin with the formation of one or more bottom electrode layers <NUM> on a substrate. In the particular embodiment illustrated two bottom electrode layers <NUM> are illustrated for the fabrication of two subsets <NUM> that may be coupled in parallel as described with regard to <FIG>. Each bottom electrode layer <NUM> includes an outside perimeter <NUM> and may be patterned to form first patterned line openings P1. A subcell layer <NUM> may then be formed over the patterned bottom electrode layer <NUM>, followed by patterning of second patterned line openings P2 as illustrated in <FIG>. As shown, the subcell layer <NUM> may optionally be wider than the bottom electrode layer <NUM> such that it surrounds the bottom electrode layer. In some embodiments, the outside perimeter <NUM> of the subcell layer <NUM> may be aligned with the outside perimeter <NUM> of the bottom electrode layer <NUM>, or laterally surround the outside perimeter <NUM> of the subcell layer. Alternatively, the subcell layer <NUM> may have the same width of the bottom electrode layer <NUM>, which may provide encapsulation function for the subcell layer <NUM>. Referring now to <FIG> a conformal transport layer is formed over the subcell layers <NUM>. This may be a single transport layer or multiple layers corresponding to the subcell layers. In accordance with embodiments, a continuous conformal transport layer <NUM> is formed over the subcell layer <NUM> and second patterned line openings P2 that separate the individual cells <NUM>. The conformal transport layer <NUM> may function to transport charge through its thickness, and not be laterally conductive so as to not short adjacent cells <NUM>. the conformal transport layer <NUM> is characterized by a resistivity greater than <NUM> ohm.

It has been observed that perovskite materials are prone to decomposition at elevated temperatures, and in particular the A-site cation of ABX<NUM> metal-halide perovskites. Additionally, perovskite materials are highly susceptible to metal induced degradation caused by halide-metal interactions. In accordance with embodiments, a conformal transport layer <NUM> may be used to protect against either of decomposition and metal induced degradation due to diffusion from a metal electrode. In accordance with embodiments, the conformal transport layer <NUM> may encapsulate a subcell layer <NUM> that includes a perovskite material absorber layer. In an embodiment, the conformal transport layer <NUM> laterally surrounds the outside perimeter <NUM> of the subcell layer <NUM>, or at least the perovskite material absorber layer of the subcell layer <NUM>. The conformal transport layer <NUM> may also be formed within the patterned line openings P2 in the subcell layer <NUM>. Following the formation of the conformal transport layer <NUM>, a patterned top electrode layer <NUM> is formed over the conformal transport layer <NUM> as illustrated in <FIG>, with the third patterned line openings P3 though the top electrode layer <NUM> separating top electrodes of adjacent cells <NUM>.

In an embodiment, a solar cell module <NUM> includes a bottom electrode layer <NUM> including a plurality of first patterned line openings P1, a subcell layer <NUM> over the bottom electrode layer <NUM>, the subcell layer <NUM> including a plurality of second patterned line openings P2, a conformal transport layer <NUM> over subcell layer <NUM> and laterally surrounding an outside perimeter <NUM> the subcell layer <NUM>, and a patterned top electrode layer <NUM> over the conformal transport layer <NUM>. In an embodiment, the patterned top electrode layer <NUM> includes a metal layer, and the bottom electrode layer <NUM> a transparent material. Exemplary transparent bottom electrode materials include poly(<NUM>,<NUM>-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), transparent conductive oxides (TCOs) such as indium tin oxide (ITO), fluorine doped tin oxide (FTO), indium zinc oxide (IZO), aluminum doped zinc oxide (AZO), cadmium stannate, etc. In an embodiment, a non-metallic intermediate layer is located between the conformal transport layer <NUM> and the subcell layer <NUM>, the non-metallic intermediate layer laterally surrounding the outside perimeter <NUM> of the subcell layer <NUM>. In an embodiment, the conformal transport layer <NUM> is additionally located within the plurality of second patterned line openings P2. Exemplary conformal transport layer materials include oxides (e.g. metal oxides), nitrides (e.g. metal nitrides), polymers, and small molecules. Exemplary metal oxides may be titanium oxide, zinc oxide, tin oxide, nickel oxide, vanadium oxide, tungsten oxide, indium oxide, any of which may be doped. For example, some TCOs may be ITO, AZO, IZO cadmium stannate. Exemplary metal nitrides include at least titanium nitride and tungsten nitride. Some exemplary polymers include poly(triaryl amine) (PTAA) and polyaniline. Some exemplary small molecules include <NUM>,<NUM>',<NUM>,<NUM>'-Tetrakis[N,N-di(<NUM>-methoxyphenyl)amino]-<NUM>,<NUM>'-spirobifluorene (spiro-MeOTAD), and fullerenes. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. In a specific implementation, the conformal transport layer <NUM> is formed of aluminum doped zinc oxide (AZO). The aluminum doping concentration need not create a high conductivity, and instead may be sufficient to only pass charge through its thickness, as opposed to laterally. In this aspect, the conformal transport layer in accordance with embodiments can function more as a barrier as opposed to conductor. For example, aluminum dopant concentration with an AZO conformal transport layer <NUM> may be less than the aluminum dopant concentration with an AZO bottom electrode layer <NUM>. Morphology can also be different compared to an AZO electrode layer. In embodiment, a conformal transport layer <NUM> in accordance with embodiments containing AZO may be amorphous, while an AZO electrode layer may be crystalline in order to provide long range mobility and less defects. The conformal transport layer <NUM> in accordance with embodiments may function to pass charge between the electrodes, yet have a sufficient resistivity to not short across a patterned electrode layer. Furthermore, the conformal transport layer <NUM> may encapsulate the subcell layer (e.g. metal-halide perovskite) to prevent perovskite-metal contact and perovskite decomposition.

Various exemplary solar cell <NUM> stack-ups are illustrated in <FIG>. <FIG> is an illustrative diagram of single junction solar cell stack-up. As illustrated, the solar cell <NUM> may include a bottom electrode layer <NUM>, a top electrode layer <NUM>, and a subcell layer <NUM> between the bottom and top electrode layers. Additionally, a conformal transport layer <NUM> may be formed on the subcell layer <NUM>. The subcell layer <NUM> includes an absorber layer <NUM> and one or more transport layers. In the embodiment illustrated, the subcell layer <NUM> includes an electron transport layer (ETL) <NUM> over the bottom electrode, an absorber layer <NUM> over the ETL <NUM>, and an optional first hole transport layer (HTL) <NUM> over the absorber layer <NUM>. The conformal transport layer <NUM> may also function as an HTL in this configuration, and physically separate the top electrode layer <NUM> from the subcell layer <NUM>, and specifically from the absorber layer <NUM>. In a specific embodiment, bottom electrode layer <NUM> is formed of a transparent material such as ITO, ETL <NUM> is formed of a n-type metal oxide such as titanium oxide, and the absorber layer <NUM> is a perovskite-based material. In an embodiment, optional HTL <NUM> is formed of PTAA or spiro-MeOTAD, while the conformal transport layer <NUM> is formed of a metal oxide such as vanadium oxide or tungsten oxide. In an embodiment, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc..

<FIG> is an illustrative diagram of tandem solar cell stack-up.

The tandem structure may include multiple absorber layers, which may be the same or different materials. In the specific embodiment described the tandem structure is a perovskite-perovskite tandem structure, though embodiments are not so limited. Electrode layer <NUM>, ETL <NUM>, and absorber layer <NUM>, and HTL <NUM> may be similar as described with regard to <FIG>. Similarly, ETL <NUM> may be similar to ETL <NUM>, absorber layer <NUM> similar to absorber layers <NUM>, and HTL <NUM> similar to HTL <NUM>. Notably, while absorber layers <NUM>, <NUM> may be formed of similar perovskite-based materials, they may be tuned for different bandgaps. A recombination layer <NUM> may be located between the stacked subcells, between ETL <NUM> and HTL <NUM>. Recombination layer <NUM> may be a transparent conducting layer such as a TCO, or ITO specifically. Conformal transport layer <NUM> and top electrode layer <NUM> may additionally be formed similarly as with regard to <FIG>.

Referring now to <FIG> is an illustrative diagram of solar cell stack-up and <FIG> is an illustrative diagram of tandem solar cell stack-up. <FIG> are similar to the structures of <FIG>, with the order of electron and hole transport layers being flipped. This change in order of layer formation may additionally change materials selection of layers. In an embodiment, HTL <NUM> is formed of a metal oxide such as nickel oxide. ETL <NUM> may be a single layer or multiple layers. In an embodiment of <FIG>, ETL <NUM> is formed of a fullerene, with the conformal transport layer <NUM> including a transparent metal oxide such a tin oxide or AZO. In an embodiment of <FIG>, ETL <NUM> may include multiple layers, for example a transparent metal oxide such as tin oxide or AZO formed over a fullerene layer. Other layers illustrated may be similar as described with regard to <FIG>.

Referring now to <FIG> a schematic cross-sectional side view illustration is provided of an interconnect with printed non-metallic intermediate layer in accordance with an embodiment. Specifically, <FIG> illustrates the interconnect between serial cells <NUM>, and additive voltages V1, V2 as shown in <FIG>. The solar cell interconnect may include a bottom electrode layer <NUM> on a substrate <NUM>, a first patterned line opening P1 in the bottom electrode layer <NUM>, a subcell layer <NUM> over the bottom electrode layer <NUM> and within the first patterned line opening P1, a second patterned line opening P2 in the subcell layer <NUM>, a non-metallic intermediate layer <NUM> along sidewalls of the second patterned line opening P2, a conformal transport layer <NUM> over the subcell layer <NUM>, on the non-metallic intermediate layer <NUM> within the second patterned line opening P2 and over the bottom electrode layer <NUM> within the second patterned line opening P1, and a top electrode layer <NUM> over the conformal transport layer <NUM> and on the conformal transport layer <NUM> within the second patterned line opening P2. The conformal transport layer <NUM> illustrated in <FIG> may be a continuous layer over and between multiple adjacent cells <NUM>, illustrated by the additive voltages V1 and V2. The conformal transport layer <NUM> may also be continuous past outside perimeter <NUM> the subcell layer <NUM> as shown in <FIG>. In the embodiment illustrated, an opening may be formed in the non-metallic intermediate layer that exposes a top surface <NUM> the bottom electrode layer <NUM>. For example, the non-metallic intermediate layer <NUM> may be formed of a non-electrically conductive material and the conformal transport layer <NUM> is in direct contact with the bottom electrode layer <NUM> in the second patterned line opening P2.

In an embodiment, the top electrode layer <NUM> includes a metal layer, while the bottom electrode layer <NUM> is formed of a transparent material. In a particular embodiment, the subcell layer <NUM> includes a perovskite absorber layer. The subcell layer <NUM> may be a single cell layer, or include multiple subcells. For example, the subcell layer <NUM> can include a tandem structure including multiple subcells. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Exemplary materials include oxides (e.g. metal oxides), nitrides (e.g. metal nitrides), polymers, and small molecules. Exemplary metal oxides may be titanium oxide, zinc oxide, tin oxide, nickel oxide, vanadium oxide, tungsten oxide, indium oxide, any of which may be doped. For example, some TCOs may be ITO, AZO, IZO cadmium stannate. Exemplary metal nitrides include at least titanium nitride and tungsten nitride. Some exemplary polymers include poly(triaryl amine) (PTAA) and polyaniline. Some exemplary small molecules include <NUM>,<NUM>',<NUM>,<NUM>'-Tetrakis[N,N-di(<NUM>-methoxyphenyl)amino]-<NUM>,<NUM>'-spirobifluorene (spiro-MeOTAD), and fullerenes. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the conformal transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness and not be laterally conductive. The conformal transport layer <NUM> has a resistivity greater than <NUM> ohm. The conformal transport layer may prevent metal diffusion, and function as an electron transport layer or hole transport layer for the solar cell <NUM>.

Still referring to <FIG>, the solar cell interconnect may include a third patterned line opening P3 in the top electrode layer <NUM>. In the particular embodiment illustrated the third patterned line opening P3 does not completely extend through a thickness of the conformal transport layer <NUM> so that the conformal transport layer can protect the underlying subcell layer <NUM>.

<FIG> is a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect of <FIG> in accordance with an embodiment. In the embodiment illustrated, the solar cell module may include a bottom electrode layer <NUM> including a plurality of first patterned line openings, a subcell layer <NUM> over the bottom electrode layer <NUM>, the subcell layer including a plurality of second patterned line openings, a conformal transport layer <NUM> over subcell layer and laterally surrounding an outside perimeter <NUM> the subcell layer <NUM>, and a patterned top electrode layer <NUM> over the conformal transport layer <NUM>. In the embodiment illustrated, a non-metallic intermediate layer <NUM> is located between the conformal transport layer <NUM> and the subcell layer <NUM>, and the non-metallic intermediate layer <NUM> laterally surrounds the outside perimeter <NUM> of the subcell layer <NUM>. Additionally, the conformal transport layer <NUM> may also surround an outside perimeter <NUM> of the non-metallic intermediate layer <NUM>.

Several variations of the embodiments illustrated in <FIG> are contemplated. For example, referring to <FIG>, the third patterned line opening P3 may partially or completely extend through any of the top electrode layer <NUM>, the conformal transport layer <NUM>, and the subcell layer <NUM>. As shown, a non-electrically conductive material <NUM> can fill the third patterning line opening P3. For example, the non-electrically conductive material <NUM> may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer <NUM> is interrupted by the third patterned line opening P3. the non-electrically conductive material <NUM> and the non-metallic intermediate layer <NUM> may be formed of the same material.

Another alternative is illustrated in <FIG>, where rather than forming a separate non-electrically conductive material in the third patterned line opening P3, the non-metallic intermediate layer <NUM> thickness may be offset within the second patterned line opening P2. In this case, the third patterned line opening P3 extends through a thickness of the non-metallic intermediate layer <NUM> rather than the subcell layer <NUM> in order to provide further protection of the subcell layer <NUM> to third patterned line opening P3. In such an embodiment, it may not be necessary to provide a further insulating material within the third patterned line opening P3. In the embodiments illustrated in <FIG>, the third patterned line opening P3 may extend through the previously continuous conformal transport layer <NUM>. <FIG> illustrate alternatively in which the break is prepared by a non-electrically conductive material <NUM> or preexisting non-metallic intermediate layer <NUM>. Alternatively, or additionally, a continuous protective layer may be formed over the entire device stack. <FIG> provides an additional alternative to that illustrated in <FIG>, in which the non-metallic intermediate layer <NUM> is underneath the third patterned line opening P3 as a precaution, even though the third patterned line opening P3 does not extend into the non-metallic intermediate layer <NUM>.

Referring now to <FIG>, <FIG> is flow chart illustrating a method of forming the interconnect of <FIG> in accordance with an embodiment. <FIG> are schematic cross-sectional side view illustrations of a method of forming the interconnect of <FIG> in accordance with an embodiment. In the following description, the processing sequence of <FIG> is made with regard to the cross-sectional side view illustrations of <FIG>. In interests of conciseness, and to not overly obscure embodiments the processing sequence variations to for the embodiments illustrated in <FIG> are not separately illustrated, and instead are described together along with <FIG>. Additionally, it is understood that certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations described herein.

As shown in <FIG> the processing sequence may begin with a substrate <NUM>. Substrate <NUM> may be a single or multiple layer substrate, including one or more layers of glass, plastic, or conductive metal foil. The bottom electrode layer <NUM> may then be formed on substrate <NUM> as illustrated in <FIG>. Bottom electrode layer <NUM> may be formed of materials such as cadmium stannate, TCOs, including ITO, FTO, IZO, etc. Referring now to <FIG>, at operation <NUM> a first patterned line opening P1 is then formed in the bottom electrode layer <NUM>. Various patterning techniques such as mechanical or laser scribing, chemical etching, or deposition with a shadow mask can be used to form P1. In an embodiment, mechanical or laser scribing is utilized in a roll-to-roll manufacturing process.

The subcell layer <NUM> is then formed over the patterned bottom electrode layer <NUM> at operation <NUM>, as shown in <FIG>. The subcell layer <NUM> generally includes a subcell including an absorber layer and one or more transport layers. In an embodiment, the subcell layer includes an absorber layer between a hole transport layer and an electron transport layer. The subcell layer <NUM> may include a single subcell, or multiple subcells such as with a tandem structure. In accordance with embodiments, the subcell layer <NUM> includes one or more absorber layers including a perovskite material. In an embodiment, the subcell layer <NUM> includes a tandem structure including a perovskite material in one or both of the subcells. For example, a tandem perovskite cell structure may include two subcells with perovskite absorber layers with different bandgaps. Perovskite materials may be characterized by the formula ABX<NUM>, with A representing a large atomic or molecular cation (e.g. Cs, methylammonium, formamidinium, etc.), with B representing a positively charged cation (e.g. metal, lead, plumbate, Sn), and X representing a negatively charged anion (e.g. halide, I, Br, Cl).

The subcell layer <NUM> is then patterned to form a second patterned line opening P2 at operation <NUM>, as illustrated in <FIG>. Various patterning techniques such as mechanical or laser scribing, chemical etching, or deposition with a shadow mask can be used to form P2. In an embodiment, mechanical or laser scribing is utilized due to chemical stability of the perovskite absorber layer(s). Referring now to <FIG>, at operation <NUM> a non-metallic intermediate layer <NUM> is formed along sidewalls <NUM> of P2. In the specific embodiment illustrated, the non-metallic intermediate layer <NUM> is first applied to fill P2 using a printing technique such as ink jet, extrusion, spraying, etc. The non-metallic intermediate layer <NUM> is formed of a non-metallic material that does not react with the absorber layer(s). In an embodiment, the non-metallic intermediate layer includes an insulator material. In an embodiment, the non-metallic intermediate layer includes a polymer such as, but are not limited to, poly(methyl methacrylate) (PMMA) and poly(vinyl alcohol) (PVA). As shown in <FIG>, the non-metallic intermediate layer <NUM> is patterned to form an opening <NUM> that may expose the bottom electrode layer <NUM>. For example, this patterning may utilize a mechanical or laser scribing.

In the particular embodiment illustrated in <FIG>, opening <NUM> substantially aligns with the middle of P2 such that lateral thicknesses of the non-metallic intermediate layer <NUM> on opposite sidewalls <NUM> are substantially the same. However, embodiments are not so limited. For example, in a processing sequence to create the interconnect structure of <FIG>, the opening <NUM> and P2 may be offset, with different lateral thicknesses of the non-metallic intermediate layer <NUM> on opposite sidewalls <NUM>.

Referring now to <FIG>, at operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer <NUM>, on the non-metallic intermediate layer within P2, and over the bottom electrode layer within P2. The conformal transport layer <NUM> may be continuous. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Exemplary materials include oxides (e.g. metal oxides), nitrides (e.g. metal nitrides), polymers, and small molecules. Exemplary metal oxides may be titanium oxide, zinc oxide, tin oxide, nickel oxide, vanadium oxide, tungsten oxide, indium oxide, any of which may be doped. For example, some TCOs may be ITO, AZO, IZO cadmium stannate. Exemplary metal nitrides include at least titanium nitride and tungsten nitride. Some exemplary polymers include poly(triaryl amine) (PTAA) and polyaniline. Some exemplary small molecules include <NUM>,<NUM>',<NUM>,<NUM>'-Tetrakis[N,N-di(<NUM>-methoxyphenyl)amino]-<NUM>,<NUM>'spirobifluorene (spiro-MeOTAD), and fullerenes. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> is characterized by a resistivity greater than <NUM> ohm. In an embodiment, the conformal transport layer also functions as an electron transport layer for the solar cell <NUM>. Alternatively, the conformal transport layer may function as a hole transport layer for the solar cell <NUM>.

In an embodiment, an AZO containing conformal transport layer <NUM> is formed using ALD or low temperature CVD to form an amorphous layer. The low temperature deposition process may not provide necessary conditions for crystal growth. This may be in contrast to a high temperature process (e.g. high temperature sputter and anneal) used for the formation of a crystalline AZO layer for use as an electrode layer.

The top electrode layer <NUM> may then be formed over the conformal transport layer and on the conformal transport layer within P2 at operation <NUM> as illustrated in <FIG>. In a particular embodiment, the top electrode layer <NUM> is deposited through a shadow mask to form the third patterned line opening P3 during deposition. This may protect underlying layers from solution processing operation. Suitable deposition technique may include evaporation, sputter, printing, and spraying the top electrode layer <NUM>. may include one or more metal layers, such as Ag, Cu, Al, Au, etc..

In an embodiment scribing is utilized to form P3 in the top electrode layer <NUM>. In the embodiments illustrated in <FIG>, the non-metallic intermediate layer <NUM> is located underneath P3, or P3 extends into or completely through the non-metallic intermediate layer <NUM>. Either configuration may provide protection for the absorber layer(s). In the embodiment illustrated in <FIG>, scribing can be used to form P3 partially or completely through any of the top electrode layer <NUM>, conformal transport layer <NUM>, and subcell layer <NUM>. In such an embodiment, P3 is partially or fully filled with an insulating material <NUM> to provide protection for the absorber layer(s).

In the foregoing description, specific processing techniques and materials selections have been provided. It is to be appreciated that that the specific processing techniques and materials selections may also be applied to the following embodiments described with regard to <FIG>. Accordingly, in interest of conciseness, detailed discussion of specific processing techniques and materials selections may not be repeated.

<FIG> is a schematic cross-sectional side view illustration of an interconnect with a conformal transport layer within a subcell patterned line opening in accordance with an embodiment. As shown, the solar cell interconnect may include a bottom electrode layer <NUM> on a substrate <NUM>, a first patterned line opening P1 in the bottom electrode layer <NUM>, a subcell layer <NUM> over the bottom electrode layer <NUM> and within the first patterned line opening P1, a second patterned line opening P2 in the subcell layer <NUM>, a non-metallic intermediate layer <NUM> along sidewalls of the second patterned line opening P2, a conformal transport layer <NUM> over the subcell layer <NUM>, on the non-metallic intermediate layer <NUM> within the second patterned line opening P2 and over the bottom electrode layer <NUM> within the second patterned line opening P1, and a top electrode layer <NUM> over the conformal transport layer <NUM> and on the conformal transport layer <NUM> within the second patterned line opening P2. The conformal transport layer <NUM> may be continuous. In the embodiment illustrated, the non-metallic intermediate layer <NUM> is a thin insulator layer or nucleation layer that is globally formed. In an embodiment, non-metallic intermediate layer <NUM> is less than <NUM> thick, such as <NUM>-<NUM> thick. As shown, the non-metallic intermediate layer <NUM> may physically separate the conformal transport layer <NUM> from bottom electrode layer <NUM>. In accordance with embodiment, the non-metallic intermediate layer <NUM> is formed of a material selected from the group consisting of an insulator, semiconductor, and carbon. The non-metallic intermediate layer <NUM> may be sufficiently thin to allow the transport of charge. Additionally, conformality of the non-metallic intermediate layer may facilitate uniform and dense growth of a subsequent conformal transport layer <NUM>. In an embodiment, the non-metallic intermediate layer <NUM> includes OH groups to help nucleate the growth of a metal oxide containing conformal transport layer <NUM>. Ethoxylated polyethyleneimine (PEIE) and polyvinyl alcohol (PVA) have such OH groups. The non-metallic intermediate layer <NUM> may also be formed of materials such as polyvinyl phenol and polystyrene. In an alternative embodiment, the non-metallic intermediate layer <NUM> may be patterned to expose the bottom electrode layer <NUM> similarly as non-metallic intermediate layer <NUM> previously described.

Referring now to <FIG>, <FIG> is flow chart illustrating a method of forming the interconnect of <FIG> in accordance with an embodiment. <FIG> are schematic cross-sectional side view illustrations of a method of forming the interconnect of <FIG> in accordance with an embodiment. In the following description, the processing sequence of <FIG> is made with regard to the cross-sectional side view illustrations of <FIG>. Additionally, it is understood that certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations described herein.

The processing sequence may begin similarly as with that of <FIG>. At operation <NUM> a first patterned line opening P1 is formed in the bottom electrode layer <NUM>. At operation <NUM> the subcell layer <NUM> is formed over the patterned bottom electrode layer <NUM>. Referring to <FIG> the subcell layer <NUM> is then patterned to form a second patterned line opening P2 at operation <NUM>. Referring to <FIG>, at operation <NUM> a non-metallic intermediate layer <NUM> is formed along sidewalls <NUM> of P2 and over the top surface of the bottom electrode layer <NUM>. The non-metallic intermediate layer <NUM> may be formed directly on the top surface <NUM> of the bottom electrode layer <NUM>. Alternatively, the non-metallic intermediate layer <NUM> may be patterned similarly as non-metallic intermediate layer <NUM> to expose the bottom electrode layer <NUM>. In accordance with embodiments, non-metallic intermediate layer <NUM> may be a nucleation layer or insulator layer less than <NUM> thick. At such a thickness, the thin non-metallic intermediate layer may be thin enough to allow the passage of charge through either conduction or tunneling. Thus, the non-metallic intermediate layer <NUM> may be a conformal layer, with thickness less than <NUM> along sidewalls <NUM> of P2, and on the top surface <NUM> of the bottom electrode layer <NUM>. The non-metallic intermediate layer may be deposited using a suitable printing technique such as spraying, evaporation and vapor transport deposition. If the non-metallic intermediate layer <NUM> is formed of an insulator or organic material, it may aid in the nucleation or adhesion of the subsequently formed conformal transport layer. The non-metallic intermediate layer <NUM> may be formed of a non-metallic material that does not react with the absorber layer(s), such as an insulator, semiconductor, and carbon. In the embodiment illustration, the non-metallic intermediate layer <NUM> is a conformal layer in order to cover the entire surface and aid in nucleation.

Referring now to <FIG>, at operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer <NUM>, on the non-metallic intermediate layer within P2. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. In an embodiment, the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> may be characterized by a resistivity greater than <NUM> ohm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell <NUM>.

The top electrode layer <NUM> may then be formed over the conformal transport layer and on the conformal transport layer within P2 at operation <NUM> as illustrated in <FIG>. In a particular embodiment, the top electrode layer <NUM> is deposited through a shadow mask to form the third patterned line opening P3 during deposition. This may protect underlying layers from solution processing operation. Suitable deposition technique may include evaporation, sputter, printing, and spraying. In an embodiment, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc. While not separately illustrated, in an alternative embodiment scribing could be performed to create P3 similarly as described and illustrated with regard to <FIG>, followed by at least partially filling with a non-electrically conductive material <NUM>.

<FIG> is a schematic cross-sectional side view illustration of an interconnect with overlapping bottom electrode and subcell patterned line openings in accordance with an embodiment. As shown, a solar cell interconnect may include a bottom electrode layer <NUM> on a substrate <NUM>, a first patterned line opening P1 in the bottom electrode layer <NUM>, a subcell layer <NUM> over the bottom electrode layer <NUM> and optionally within the first patterned line opening P1, a second patterned line opening P2 in the subcell layer <NUM>, a non-metallic intermediate layer <NUM> along sidewalls of the second patterned line opening P2, a conformal transport layer <NUM> over the subcell layer <NUM>, on the non-metallic intermediate layer <NUM> within the second patterned line opening P2 and over the bottom electrode layer <NUM> within the second patterned line opening P1, and a top electrode layer <NUM> over the conformal transport layer <NUM> and on the conformal transport layer <NUM> within the second patterned line opening P2. The conformal transport layer <NUM> may be continuous. In the embodiment illustrated, P2 overlaps P1. Also shown, are the non-metallic intermediate layer <NUM> formed along one sidewall <NUM> of P2 and on the substrate <NUM> inside of P1, and the non-metallic intermediate layer <NUM> formed along the opposite sidewall <NUM> of P2 and on the bottom electrode layer <NUM>. An opening in the non-metallic intermediate layer <NUM> exposes a top surface the bottom electrode layer. The conformal transport layer <NUM> of the embodiment illustrated in <FIG> may be in direct contact with the bottom electrode layer <NUM>.

In accordance with embodimetns, <FIG> illustrates the interconnect between serial cells <NUM>, and additive voltages V1, V2 as shown in <FIG>. Thus, the corresponding voltage V1 of the first cell on the left side of <FIG> and the corresponding voltage V2 of the second cell on the right side of <FIG> are additive. In an embodiment, a solar cell serial interconnect includes a bottom electrode layer <NUM>, a first patterned line opening P1 in the bottom electrode layer that separates the bottom electrode layer <NUM> into a first bottom electrode layer (e.g. left side) of a first cell (e.g. left side) and a second bottom electrode elayer (e.g. right side) of a second cell (e.g. right side). A subcell layer <NUM> is over the bottom electrode layer <NUM>, and a second patterned line opening P2 is in the subcell layer <NUM> to separate the subcell layer <NUM> into a first subcell layer (e.g. left side) of the first cell and a second subcell layer (e.g. right side) of the second cell. The second patterned line opening P2 includes a first sidewall <NUM> along the first subcell layer and a second sidewall <NUM> along the second subcell layer laterally opposite to the first sidewall. A non-metallic intermediate layer <NUM> is along the first sidewall and the second sidewall of the second patterned line opening P2. In the illustrated embodiment, a continuous conformal transport layer <NUM> spans over the first subcell layer (e.g. left side), the second subcell layer (e.g. right side), on the non-metallic intermediate layer <NUM> within the second patterned line opening P2, and over the second bottom electrode layer (e.g. right side) within the second patterned line opening P2. A top electrode layer <NUM> is over the continuous conformal transport layer <NUM> and on the continuous conformal transport layer <NUM> within the second patterned line opening P2. A third patterned line opening P3 is formed in the top electrode layer <NUM> to separate the top electrode layer into a first top electrode layer (e.g. left side) of the first cell and a second top electrode layer (e.g. right side) of the second cell. In such a configuration, the second bottom electrode layer (e.g. right side) of the second subcell and the first top electrode layer (e.g. left side) of the first subcell are serially interconnected.

<FIG> is a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect of <FIG> in accordance with an embodiment. Similar to the embodiment illustrated in <FIG>, the solar cell module may include a bottom electrode layer <NUM> including a plurality of first patterned line openings, a subcell layer <NUM> over the bottom electrode layer <NUM>, the subcell layer including a plurality of second patterned line openings, a conformal transport layer <NUM> over subcell layer and laterally surrounding an outside perimeter <NUM> the subcell layer <NUM>, and a patterned top electrode layer <NUM> over the conformal transport layer <NUM>. In the embodiment illustrated, a non-metallic intermediate layer <NUM> is located between the conformal transport layer <NUM> and the subcell layer <NUM>, and the non-metallic intermediate layer <NUM> laterally surrounds the outside perimeter <NUM> of the subcell layer <NUM>. Additionally, the conformal transport layer <NUM> may also surround an outside perimeter <NUM> of the non-metallic intermediate layer <NUM>.

Several variations of the embodiments illustrated in <FIG> are contemplated. For example, referring to <FIG>, the third patterned line opening P3 may partially or completely extend through any of the top electrode layer <NUM>, the conformal transport layer <NUM>, and the subcell layer <NUM>. As shown, a non-electrically conductive material <NUM> can fill the third patterning line opening P3. For example, the non-electrically conductive material <NUM> may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer <NUM> is interrupted by the third patterned line opening P3. In an embodiment the non-electrically conductive material <NUM> and the non-metallic intermediate layer <NUM> are formed of the same material.

Referring to <FIG> a bottom electrode layer <NUM> may first be formed on a substrate <NUM>, followed by the formation of subcell layer <NUM> as illustrated in <FIG>. At operation <NUM>, a first patterned line opening P1 is formed through the subcell layer <NUM>, and bottom electrode layer <NUM>. At operation <NUM> a second patterned line opening P2 is formed in the subcell layer <NUM>, where P2 overlaps P1. P2 may be wider than P1. Additionally, P2 and P1 may share a same sidewall <NUM> in the subcell layer <NUM>.

Referring now to <FIG>, at operation <NUM> a non-metallic intermediate layer <NUM> is formed along sidewalls <NUM> of P2. In the specific embodiment illustrated, the non-metallic intermediate layer <NUM> is first applied to fill P2 using a printing technique such as ink jet, extrusion, spraying, etc. The non-metallic intermediate layer <NUM> is formed of a non-metallic material that does not react with the absorber layer(s), such as a polymer, carbon or carbon/polymer blend. In an embodiment, the non-metallic intermediate layer is an insulating material. As shown in <FIG>, the non-metallic intermediate layer <NUM> is patterned to form an opening <NUM> that may expose the bottom electrode layer <NUM> and optionally substrate <NUM>. For example, this patterning may utilize laser scribing. In the particular embodiment illustrated in <FIG>, opening <NUM> substantially aligns with the middle of P2 such that lateral thicknesses of the non-metallic intermediate layer <NUM> on opposite sidewalls <NUM> are substantially the same. However, embodiments are not so limited.

Referring now to <FIG>, at operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer <NUM>, and on the non-metallic intermediate layer <NUM> within P2. In an embodiment, the conformal transport layer <NUM> is formed on the top surface of the bottom electrode <NUM>. The conformal transport layer <NUM> may also be formed within P1. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> is characterized by a resistivity greater than <NUM> ohm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell <NUM>.

The top electrode layer <NUM> may then be formed over the conformal transport layer and on the conformal transport layer within P2 at operation <NUM> as illustrated in <FIG>. In a particular embodiment, the top electrode layer <NUM> is deposited through a shadow mask to form the third patterned line opening P3 during deposition. This may protect underlying layers from solution processing operation. Suitable deposition technique may include evaporation, sputter, printing, and spraying. In an embodiment, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In the alternative embodiment illustrated in <FIG>, scribing could be performed to create P3 similarly as described and illustrated with regard to <FIG>, followed by at least partially filling with a non-electrically conductive material <NUM>.

<FIG> is a schematic cross-sectional side view illustration of an interconnect, not forming part of the claimed invention, with a conductive plug in a subcell patterned line opening. As shown, the solar cell interconnect may include a bottom electrode layer <NUM>, a first patterned line opening P1 in the bottom electrode layer <NUM>, a subcell layer <NUM> over the bottom electrode layer, a second patterned line opening P2 in the subcell layer <NUM>, a conductive plug <NUM> within P2, a conformal transport layer <NUM> over the subcell layer <NUM> and the conductive plug <NUM>, a top electrode layer <NUM> over the conformal transport layer <NUM>, and a third patterned line opening P3 in the top electrode layer <NUM>. The conformal transport layer <NUM> may be continuous. In the embodiment illustrated, P3 does not completely extend through a thickness of the conformal transport layer <NUM>.

<FIG> is a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect of <FIG>. Similar to the embodiment illustrated in <FIG>, the solar cell module may include a bottom electrode layer <NUM> including a plurality of first patterned line openings, a subcell layer <NUM> over the bottom electrode layer <NUM>, the subcell layer including a plurality of second patterned line openings, a conformal transport layer <NUM> over subcell layer and laterally surrounding an outside perimeter <NUM> the subcell layer <NUM>, and a patterned top electrode layer <NUM> over the conformal transport layer <NUM>.

Several variations of the embodiments illustrated in <FIG> are contemplated. For example, referring to <FIG>, not forming part of the claimed invention, the third patterned line opening P3 may partially or completely extend through any of the top electrode layer <NUM>, the conformal transport layer <NUM>, and the subcell layer <NUM>. As shown, a non-electrically conductive material <NUM> can fill the third patterning line opening P3. For example, the non-electrically conductive material <NUM> may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer <NUM> is interrupted by the third patterned line opening P3.

Referring now to <FIG>, <FIG> is flow chart illustrating a method of forming the interconnect of <FIG>. <FIG> are schematic cross-sectional side view illustrations of a method of forming the interconnect of <FIG>. In the following description, the process sequence of <FIG> is made with regard to the cross-sectional side view illustrations of <FIG>. Additionally, it is understood that certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations described herein.

The processing sequence may begin similarly as with that of <FIG>. At operation <NUM> a first patterned line opening P1 is formed in the bottom electrode layer <NUM>. At operation <NUM> the subcell layer <NUM> is formed over the patterned bottom electrode layer <NUM>. Referring to <FIG> the subcell layer <NUM> is then patterned to form a second patterned line opening P2 at operation <NUM>. Referring to <FIG>, at operation <NUM> an (electrically) conductive plug <NUM> is formed within P2 and on the bottom electrode layer <NUM>. The conductive plug <NUM> may be formed of materials that do not react with the absorber layer(s), such as carbon or a carbon/polymer blend, printed ITO nanoparticles or other TCO nanoparticles. The conductive plug <NUM> may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. so that further patterning is not necessary. A conductivity of the conductive plug <NUM> may only be greater than about <NUM>. <NUM>/cm due to the short distance of the interconnection based on the thin film thickness in the <NUM>-<NUM> range. Such a low conductivity can be achieved by a range of materials that do not react with the perovskite such as carbon (bulk conductivity around <NUM>-<NUM>/cm) and ITO nanoparticles. In an embodiment, the conductive plug <NUM> includes particles dispersed in a matrix (e.g. polymer matrix). The carbon and/or TCO particles can be mixed into a polymer blend in order to make it easier to suspend the carbon or TCO nanoparticles in a solvent and deposit the interconnects through a printing technique like ink jet or spraying. Due to the low conductivity required, a very high conductive particle to polymer ratio is not required. Such a polymer could be a binder like poly(vinylidene fluoride) (PVDF), polyvinyl fluoride, polyvinylchloride, polystyrene, PMMA, PVA, polyvinyl phenol, polyethylene glycol, etc. The carbon may be graphite or carbon black in an embodiment, but could include graphene or carbon nanotubes or amorphous carbon. The TCO particles may be ITO or IZO nanoparticles with diameters between <NUM>-<NUM> in an embodiment, but could be AZO, Sb:SnO<NUM>, zinc tin oxide, cadmium stannate and could be microparticles with diameters between <NUM>-<NUM>.

Referring now to <FIG>, at operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer <NUM> and over the electrically conductive plug <NUM> within P2. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer may be less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> may be characterized by a resistivity greater than <NUM> ohm. the conformal transport layer may also function as an electron transport layer to the subcell layer <NUM>.

The top electrode layer <NUM> may then be formed over the conformal transport layer <NUM> at operation <NUM> as illustrated in <FIG>. the top electrode layer <NUM> may be deposited through a shadow mask to form the third patterned line opening P3 during deposition. This may protect underlying layers from solution processing operation. Suitable deposition technique may include evaporation, sputter, printing, and spraying. In an example, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In an alternative example illustrated in <FIG>, scribing could be performed to create P3 similarly as described and illustrated with regard to <FIG>, followed by at least partially filling with a non-electrically conductive material <NUM>.

<FIG> is a schematic cross-sectional side view illustration of an interconnect, not forming part of the claimed invention, with a conductive plug in a subcell patterned line opening. As shown, the solar cell interconnect may include a bottom electrode layer <NUM>, a first patterned line opening P1 in the bottom electrode layer <NUM>, a subcell layer <NUM> over the bottom electrode layer, a second patterned line opening P2 in the subcell layer <NUM>, a conductive plug <NUM> within P2, a conformal transport layer <NUM> over the subcell layer <NUM> and the conductive plug <NUM>, a top electrode layer <NUM> over the conformal transport layer <NUM>, and a third patterned line opening P3 in the top electrode layer <NUM>. The conformal transport layer <NUM> may be continuous. P3 may not completely extend through a thickness of the conformal transport layer <NUM>. In the particular embodiment illustrated P2 overlaps P1. Additionally, a non-metallic intermediate layer <NUM> may be formed along a single sidewall <NUM> of P2. Non-metallic intermediate layer <NUM> may be formed of the same materials as the non-metallic intermediate layer <NUM> previously described. More specifically, the non-metallic intermediate layer <NUM> may be formed along a single sidewall <NUM> of P1 that is shared with P1. The non-metallic intermediate layer <NUM> may be formed within P1. Additionally, P3 may optionally overlap P2.

In the example illustrated in <FIG>, a lateral edge <NUM> of the non-metallic intermediate layer <NUM> is over the bottom electrode layer <NUM>. The lateral edge <NUM> may be located elsewhere. For example, the variation illustrated in <FIG>, not forming part of the claimed invention, shows lateral edge <NUM> located within Pl.

<FIG> is a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including an interconnect of <FIG>. Similar to the embodiment illustrated in <FIG>, the solar cell module may include a bottom electrode layer <NUM> including a plurality of first patterned line openings, a subcell layer <NUM> over the bottom electrode layer <NUM>, the subcell layer including a plurality of second patterned line openings, a conformal transport layer <NUM> over subcell layer and laterally surrounding an outside perimeter <NUM> the subcell layer <NUM>, and a patterned top electrode layer <NUM> over the conformal transport layer <NUM>. In the embodiment illustrated, a non-metallic intermediate layer <NUM> is located between the conformal transport layer <NUM> and the subcell layer <NUM>, and the non-metallic intermediate layer <NUM> laterally surrounds the outside perimeter <NUM> of the subcell layer <NUM>. Additionally, the conformal transport layer <NUM> may also surround an outside perimeter <NUM> of the non-metallic intermediate layer <NUM>.

Several variations of the embodiments illustrated in <FIG> are contemplated. For example, referring to <FIG>, not forming part of the claimed invention, the third patterned line opening P3 may partially or completely extend through any of the top electrode layer <NUM>, the conformal transport layer <NUM>, and the subcell layer <NUM>. As shown, a non-electrically conductive material <NUM> can fill the third patterning line opening P3. For example, the non-electrically conductive material <NUM> may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer <NUM> is interrupted by the third patterned line opening P3. In an embodiment the non-electrically conductive material <NUM> and the non-metallic intermediate layer <NUM> are formed of the same material.

Referring now to <FIG>, <FIG> is flow chart illustrating a method of forming the interconnect of <FIG>. <FIG> are schematic cross-sectional side view illustrations of a method of forming the interconnect of <FIG>. In the following description, the processing sequence of <FIG> is made with regard to the cross-sectional side view illustrations of <FIG>. Additionally, it is understood that certain examples may be practiced without one or more of these specific details, or in combination with other known methods and configurations described herein.

The processing sequence may begin similarly as with that of <FIG>. At operation <NUM> a first patterned line opening P1 is formed in the bottom electrode layer <NUM>. At operation <NUM> the subcell layer <NUM> is formed over the patterned bottom electrode layer <NUM> as shown in <FIG>. Referring to <FIG> the subcell layer <NUM> is then patterned to form a second patterned line opening P2 at operation <NUM>. Referring to <FIG>, at operation <NUM> a non-metallic intermediate layer <NUM> is formed along a sidewall <NUM> of P2. Non-metallic intermediate layer <NUM> may be formed along a single sidewall <NUM> in accordance with an embodiment, and as described with regard to <FIG>. In an embodiment, non-metallic intermediate layer <NUM> is a polymer material such as, but not limited to, poly(methyl methacrylate) (PMMA),poly(vinyl alcohol) (PVA), and polystyrene. Non-metallic intermediate layer <NUM> may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. In an embodiment, opening <NUM> exists between a sidewall <NUM> of the non-metallic intermediate layer <NUM> and a sidewall <NUM> of P2. Opening <NUM> may expose the bottom electrode <NUM>.

Referring now to <FIG>, at operation <NUM> a conductive plug <NUM> is formed within P2, or more specifically within opening <NUM> within P2. Conductive plug <NUM> may fill opening <NUM> between the non-metallic intermediate layer <NUM> and the sidewall <NUM> P2 that is laterally opposite the sidewall <NUM> which is covered by non-metallic intermediate layer <NUM>. In an embodiment, conductive plug <NUM> is in contact with the bottom electrode layer <NUM>. Conductive plug <NUM> may optionally be formed over the non-metallic intermediate layer <NUM>. The conductive plug <NUM> may be formed of materials that do not react with the absorber layer(s), such as carbon or a carbon/polymer blend, ITO nanoparticles, and TCO nanoparticles. The conductive plug <NUM> may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. so that further patterning is not necessary.

Referring now to <FIG>, at operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer <NUM> and over the electrically conductive plug <NUM> within P2. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> is characterized by a resistivity greater than <NUM> ohm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell <NUM>.

The top electrode layer <NUM> may then be formed over the conformal transport layer <NUM> at operation <NUM> as illustrated in <FIG>. the top electrode layer <NUM> may be deposited through a shadow mask to form the third patterned line opening P3 during deposition. This may protect underlying layers from solution processing operation. Suitable deposition technique may include evaporation, sputter, printing, and spraying. In an embodiment, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In an alternative example illustrated in <FIG>, scribing could be performed to create P3 similarly as described and illustrated with regard to <FIG>, followed by at least partially filling with a non-electrically conductive material <NUM>.

<FIG> are schematic cross-sectional side view illustrations of an interconnect, not forming part of the claimed invention, with a printed non-metallic intermediate layer and conductive plug wthin a subcell patterned line opening. <FIG> is a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including an interconnect of <FIG>. As shown, the solar cell interconnect may include a bottom electrode layer <NUM>, a first patterned line opening P1 in the bottom electrode layer, a subcell layer <NUM> over the bottom electrode layer <NUM>, a conformal transport layer <NUM> over the subcell layer <NUM>, a top electrode layer <NUM> over the conformal transport layer <NUM>, and a second patterned line opening P2 through the top electrode layer <NUM>, the conformal transport layer <NUM> and the subcell layer <NUM>. A conductive plug <NUM> is formed within the second patterned line opening P2 to make electrical connection between the top electrode layer <NUM> of one cell and the bottom electrode layer <NUM> of an adjacent cell. The second patterned line opening P2 may overlap the first patented line opening P1. For example, P2 may completely overlap P1 and be wider than P1.

The conformal transport layer <NUM> may be a continuous layer prior to patterning of P2. Referring to <FIG>, the conformal transport layer <NUM> may laterally surround the outside perimeter <NUM> of the subcell layer <NUM>, and optionally outside perimeter <NUM> of the bottom electrode layer <NUM>. The solar cell interconnect may further include a non-metallic intermediate layer <NUM> along one or more sidewalls of the second patterned line opening P2. For example, this may be sidewalls <NUM> of the subcell layer <NUM>, as well as sidewalls of the conformal transport layer <NUM> and top electrode layer <NUM>. In the embodiment illustrated in <FIG> a third patterned line opening P3 is formed in the conductive plug <NUM> within the second line opening P2. The third patterned line opening P3 may expose the bottom electrode layer <NUM>. In the embodiment illustrated in <FIG> the non-metallic intermediate layer <NUM> is formed on both laterally opposite sidewalls of the second patterned line opening P2, and a third patterned line opening P3 is formed in the non-metallic intermediate layer <NUM>. The third patterned line opening P3 extends into the second patterned line opening P2, and the conductive plug <NUM> fills the third patterned line opening P3 in the non-metallic intermediate layer. In accordance with embodiments, the top electrode layer <NUM> of <FIG> can include metal layer, and the bottom electrode layer <NUM> can include a transparent material.

Referring now to <FIG>, <FIG> is flow chart illustrating a method of forming the interconnects of <FIG>. <FIG> are schematic cross-sectional side view illustrations of a method of forming the interconnects of <FIG>. In the following description, the processing sequence of <FIG> is made with regard to the cross-sectional side view illustrations of <FIG>. Additionally, it is understood that certain examples may be practiced without one or more of these specific details, or in combination with other known methods and configurations described herein.

The processing sequence may begin similarly as with that of <FIG>. At operation <NUM> a first patterned line opening P1 is formed in the bottom electrode layer <NUM>. At operation <NUM> the subcell layer <NUM> is formed over the patterned bottom electrode layer <NUM>. At operation <NUM> a conformal transport layer <NUM> is formed over the subcell layer, and at operation <NUM> a top electrode layer <NUM> is formed over the conformal transport layer <NUM> as illustrated in <FIG>. The conformal transport layer <NUM> may function to encapsulate and protect the subcell layer <NUM>, for example from decomposition and metal diffusion. Suitable deposition techniques to form a conformal layer may include chemical vapor deposition (CVD), atomic layer deposition (ALD), solution coating and evaporation. the conformal transport layer is less than <NUM>,<NUM> thick, such as less than <NUM> thick, or more specifically less than <NUM> thick such as <NUM>-<NUM> thick. The conformal transport layer may be doped. For example, the transport layer may be AZO. The conformal transport layer may be sufficiently thin to transport charge through its thickness, and not be laterally conductive. The conformal transport layer <NUM> is characterized by a resistivity greater than <NUM> ohm. In an example, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell <NUM>. The top electrode layer <NUM> may be formed using suitable deposition technique such as evaporation, sputter, printing, and spraying. In an example, the top electrode layer <NUM> includes one or more metal layers, such as Ag, Cu, Al, Au, etc..

Referring now to <FIG> at operation <NUM> a second patterned line opening P2 is then formed through the top electrode layer <NUM>, the conformal transport layer <NUM>, and the subcell layer <NUM>. As shown, the P2 may overlap P1, and may be wider than P1. Formation of P2 may also remove any subcell layer <NUM> material from within P1.

A non-metallic intermediate layer <NUM> may then be formed along one, or both, sidewalls of P2 as shown in <FIG>. Non-metallic intermediate layer <NUM> may be formed of the same materials as the non-metallic intermediate layer <NUM> previously described. Non-metallic intermediate layer <NUM> may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. In an embodiment such as <FIG>, a third patterned line opening P3 may be formed in the non-metallic intermediate layer <NUM>. This may be accomplished through the deposition technique. Alternatively this may be accomplished through patterning, such as scribing. This may increase deposition tolerances for the non-metallic intermediate layer <NUM>. In an example such as <FIG>, the non-metallic intermediate layer <NUM> may be formed along a single sidewall of P2. In both configurations the non-metallic intermediate layer <NUM> can insulate the top electrode layer <NUM> from the bottom electrode layer <NUM> after formation of the plug <NUM>.

Referring to <FIG>, at operation <NUM> an (electrically) conductive plug <NUM> is formed within P2 and on the bottom electrode layer <NUM>. In the example of <FIG>, it is not necessary to further pattern the conductive plug <NUM>. In the example of <FIG>, a third patterned line opening P3 may be formed in the conductive plug <NUM> to prevent shorting across the top electrode layer <NUM>.

The conductive plug <NUM> may be formed of materials that do not react with the absorber layer(s), such as carbon or a carbon/polymer blend, printed ITO nanoparticles or other TCO nanoparticles. The conductive plug <NUM> may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. so that further patterning is not necessary. A conductivity of the conductive plug <NUM> may only be greater than about <NUM>/cm due to the short distance of the interconnection based on the thin film thickness in the <NUM>-<NUM> range. Such a low conductivity can be achieved by a range of materials that do not react with the perovskite such as carbon (bulk conductivity around <NUM>-<NUM>/cm) and ITO nanoparticles. In an example, the conductive plug <NUM> includes particles dispersed in a matrix (e.g. polymer matrix). The carbon and/or TCO particles can be mixed into a polymer blend in order to make it easier to suspend the carbon or TCO nanoparticles in a solvent and deposit the interconnects through a printing technique like ink jet or spraying. Due to the low conductivity required, a very high conductive particle to polymer ratio is not required. Such a polymer could be a binder like poly(vinylidene fluoride) (PVDF), polyvinyl fluoride, polyvinyl chloride, polystyrene, PMMA, PVA, polyvinyl phenol, polyethylene glycol, etc. The carbon may be graphite or carbon black in an embodiment, but could include graphene or carbon nanotubes or amorphous carbon. The TCO particles may be ITO or IZO nanoparticles with diameters between <NUM>-<NUM> in an embodiment, but could be AZO, Sb: SnO<NUM>, zinc tin oxide, cadmium stannate and could be microparticles with diameters between <NUM>-<NUM>.

Claim 1:
A solar cell serial interconnect comprising:
a bottom electrode layer (<NUM>);
a first patterned line opening (P1) in the bottom electrode layer that separates the bottom electrode layer into a first bottom electrode layer of a first cell and a second bottom electrode layer of a second cell;
a subcell layer (<NUM>) over the bottom electrode layer;
a second patterned line opening (P2) in the subcell layer that separates the subcell layer into a first subcell layer of the first cell and a second subcell layer of the second cell, the second patterned line opening including a first sidewall (<NUM>) along the first subcell layer and a second sidewall (<NUM>) along the second subcell layer laterally opposite to the first sidewall;
a non-metallic intermediate layer (<NUM>, <NUM>) along the first sidewall and the second sidewall of the second patterned line opening;
a continuous conformal charge transport layer (<NUM>) that spans over the first subcell layer, the second subcell layer, on the non-metallic intermediate layer within the second patterned line opening, and over the second bottom electrode layer within the second patterned line opening;
wherein the continuous conformal charge transport layer has a resistivity greater than <NUM> ohm.cm and is less than <NUM>,<NUM> thick;
a top electrode layer (<NUM>) over the continuous conformal charge transport layer and on the continuous conformal charge transport layer within the second patterned line opening; and
a third patterned line opening (P3) in the top electrode layer that separates the top electrode layer into a first top electrode layer of the first cell and a second top electrode layer of the second cell;
wherein the second bottom electrode layer of the second subcell and the first top electrode layer of the first subcell are serially interconnected.