Stable perovskite module interconnects

Thin-film solar cell modules and serial cell-to-cell interconnect structures and methods of fabrication are described. In an embodiment, solar cell module and interconnect includes a conformal transport layer over a subcell layer. The conformal transport layer may also laterally surround an outside perimeter the subcell layer.

BACKGROUND

Field

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

Background Information

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.

SUMMARY

Thin-film solar cell modules and serial cell-to-cell interconnect structures and methods of fabrication are described. In particular embodiments describe structures and fabrication sequences that may protect the integrity of the subcell absorber material, such as a metal-halide perovskite, from decomposition and allow the integration of adjacent metal layers.

In an embodiment 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 P1in 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 P2in 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 P2and 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 P3may additionally be formed through at least the top electrode layer.

In an embodiment, a solar cell interconnect includes a bottom electrode layer, a first patterned line opening P1in the bottom electrode layer, a subcell layer over the bottom electrode layer, a second patterned line opening P2in 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 P3in the top electrode layer. The conductive plug may substantially fill P2in 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 P1that is shared with P1.

In an embodiment, a solar cell interconnect includes a bottom electrode layer, a first patterned line opening P1in 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 P2through 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 P3in 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 P3scribe may be filled with a non-electrically conductive. The P3scribe may possibly extend into the non-metallic intermediate layer. In some embodiments P1and P2do not overlap. In other embodiments, P2overlaps P1.

DETAILED DESCRIPTION

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 and thin-film fabrication methods 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.

Referring now toFIG. 1a schematic top view illustration is provided of a solar cell module in accordance with embodiments. As shown, the module100includes a plurality of cells120(also referred to as solar cells) coupled in series with interconnects130, with the front of one cell connected to the rear of the next cell so that their voltages (V1. . . Vn) add. The plurality of cells120may be arranged into one or more subsets110(e.g. strings) coupled in parallel, which may have the effect of decreasing total module voltage.

A thin-film solar cell120commonly includes a subcell between two electrodes, at least one of which being transparent. As described in more detail with regard toFIGS. 3A-3BandFIGS. 4A-4B, 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 cells120which 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 interconnects130, such as a first patterned line opening P1through a bottom electrode, a second patterned line opening P2through the subcell which includes the absorber and transport layer(s), and a third patterned line opening P3through a top/rear electrode to electrically isolate adjacent cells120.

Referring now toFIGS. 2A-2D, schematic top view illustrations are provided of a method of fabricating a solar cell module100in accordance with embodiments. As shown inFIG. 2A, the sequence may begin with the formation of one or more bottom electrode layers210on a substrate. In the particular embodiment illustrated two bottom electrode layers210are illustrated for the fabrication of two subsets110that may be coupled in parallel as described with regard toFIG. 1. Each bottom electrode layer210includes an outside perimeter214and may be patterned to form first patterned line openings P1. A subcell layer220may then be formed over the patterned bottom electrode layer210, followed by patterning of second patterned line openings P2as illustrated inFIG. 2B. As shown, the subcell layer220may optionally be wider than the bottom electrode layer210such that it surrounds the bottom electrode layer. In some embodiments, the outside perimeter224of the subcell layer220may be aligned with the outside perimeter214of the bottom electrode layer210, or laterally surround the outside perimeter224of the subcell layer. Alternatively, the subcell layer220may have the same width of the bottom electrode layer210, which may provide encapsulation function for the subcell layer220. Referring now toFIG. 2Ca conformal transport layer is formed over the subcell layers220. This may be a single transport layer or multiple layers corresponding to the subcell layers. In accordance with embodiments, a continuous conformal transport layer240is formed over the subcell layer220and second patterned line openings P2that separate the individual cells120. The conformal transport layer240may function to transport charge through its thickness, and not be laterally conductive so as to not short adjacent cells120. In an embodiment, the conformal transport layer240is characterized by a resistivity greater than 0.1 ohm·cm.

It has been observed that perovskite materials are prone to decomposition at elevated temperatures, and in particular the A-site cation of ABX3metal-halide perovskites. Additionally, perovskite materials are highly susceptible to metal induced degradation caused by halide-metal interactions. In accordance with embodiments, a conformal transport layer240may 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 layer240may encapsulate a subcell layer220that includes a perovskite material absorber layer. In an embodiment, the conformal transport layer240laterally surrounds the outside perimeter224of the subcell layer220, or at least the perovskite material absorber layer of the subcell layer220. The conformal transport layer240may also be formed within the patterned line openings P2in the subcell layer220. Following the formation of the conformal transport layer240, a patterned top electrode layer250is formed over the conformal transport layer240as illustrated inFIG. 2D, with the third patterned line openings P3though the top electrode layer250separating top electrodes of adjacent cells120.

In an embodiment, a solar cell module100includes a bottom electrode layer210including a plurality of first patterned line openings P1, a subcell layer220over the bottom electrode layer210, the subcell layer220including a plurality of second patterned line openings P2, a conformal transport layer240over subcell layer220and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240. In an embodiment, the patterned top electrode layer250includes a metal layer, and the bottom electrode layer210a transparent material. Exemplary transparent bottom electrode materials include poly(3,4-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 layer240and the subcell layer220, the non-metallic intermediate layer laterally surrounding the outside perimeter224of the subcell layer220. In an embodiment, the conformal transport layer240is 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 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-MeOTAD), and fullerenes. In an embodiment, the conformal transport layer is less than 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm thick. In a specific implementation, the conformal transport layer240is 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 layer240may be less than the aluminum dopant concentration with an AZO bottom electrode layer210. Morphology can also be different compared to an AZO electrode layer. In embodiment, a conformal transport layer240in 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 layer240in 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 layer240may encapsulate the subcell layer (e.g. metal-halide perovskite) to prevent perovskite-metal contact and perovskite decomposition.

Various exemplary solar cell120stack-ups are illustrated inFIGS. 3A-4B.FIG. 3Ais an illustrative diagram of single junction solar cell stack-up in accordance with an embodiment. As illustrated, the solar cell120may include a bottom electrode layer210, a top electrode layer250, and a subcell layer220between the bottom and top electrode layers. Additionally, a conformal transport layer240may be formed on the subcell layer220. The subcell layer200includes an absorber layer320and one or more transport layers. In the embodiment illustrated, the subcell layer200includes an electron transport layer (ETL)310over the bottom electrode, an absorber layer320over the ETL310, and an optional first hole transport layer (HTL)330over the absorber layer320. The conformal transport layer240may also function as an HTL in this configuration, and physically separate the top electrode layer250from the subcell layer220, and specifically from the absorber layer320. In a specific embodiment, bottom electrode layer210is formed of a transparent material such as ITO, ETL310is formed of a n-type metal oxide such as titanium oxide, and the absorber layer320is a perovskite-based material. In an embodiment, optional HTL330is formed of PTAA or spiro-MeOTAD, while the conformal transport layer240is formed of a metal oxide such as vanadium oxide or tungsten oxide. In an embodiment, the top electrode layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc.

FIG. 3Bis an illustrative diagram of tandem solar cell stack-up in accordance with embodiments. 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 layer210, ETL310, and absorber layer320, and HTL330may be similar as described with regard toFIG. 3A. Similarly, ETL350may be similar to ETL310, absorber layer360similar to absorber layers320, and HTL370similar to HTL330. Notably, while absorber layers320,360may be formed of similar perovskite-based materials, they may be tuned for different bandgaps. A recombination layer350may be located between the stacked subcells, between ETL350and HTL330.

Recombination layer350may be a transparent conducting layer such as a TCO, or ITO specifically. Conformal transport layer240and top electrode layer250may additionally be formed similarly as with regard toFIG. 3A.

Referring now toFIGS. 4A-4B,FIG. 4Ais an illustrative diagram of solar cell stack-up in accordance with an embodiment, andFIG. 4Bis an illustrative diagram of tandem solar cell stack-up in accordance with an embodiment.FIGS. 4A-4Bare similar to the structures ofFIGS. 3A-3B, 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, HTL320is formed of a metal oxide such as nickel oxide. ETL310may be a single layer or multiple layers. In an embodiment ofFIG. 4A, ETL310is formed of a fullerene, with the conformal transport layer240including a transparent metal oxide such a tin oxide or AZO. In an embodiment ofFIG. 4B, ETL310may 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 toFIGS. 3A-3B.

Referring now toFIG. 5Aa schematic cross-sectional side view illustration is provided of an interconnect with printed non-metallic intermediate layer in accordance with an embodiment. Specifically,FIG. 5Aillustrates the interconnect between serial cells120, and additive voltages V1, V2as shown inFIG. 1. The solar cell interconnect may include a bottom electrode layer210on a substrate202, a first patterned line opening P1in the bottom electrode layer210, a subcell layer220over the bottom electrode layer210and within the first patterned line opening P1, a second patterned line opening P2in the subcell layer220, a non-metallic intermediate layer230along sidewalls of the second patterned line opening P2, a conformal transport layer240over the subcell layer220, on the non-metallic intermediate layer230within the second patterned line opening P2and over the bottom electrode layer210within the second patterned line opening P1, and a top electrode layer250over the conformal transport layer240and on the conformal transport layer240within the second patterned line opening P2. The conformal transport layer240illustrated inFIG. 5Amay be a continuous layer over and between multiple adjacent cells110, illustrated by the additive voltages V1and V2. The conformal transport layer240may also be continuous past outside perimeter224the subcell layer220as shown inFIG. 5B. In the embodiment illustrated, an opening may be formed in the non-metallic intermediate layer that exposes a top surface211the bottom electrode layer210. For example, the non-metallic intermediate layer230may be formed of a non-electrically conductive material and the conformal transport layer240is in direct contact with the bottom electrode layer210in the second patterned line opening P2.

In an embodiment, the top electrode layer250includes a metal layer, while the bottom electrode layer210is formed of a transparent material. In a particular embodiment, the subcell layer220includes a perovskite absorber layer. The subcell layer220may be a single cell layer, or include multiple subcells. For example, the subcell layer220can include a tandem structure including multiple subcells. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-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. In an embodiment, the conformal transport layer is less than 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. The conformal transport layer may prevent metal diffusion, and function as an electron transport layer or hole transport layer for the solar cell120.

Still referring toFIG. 5A, the solar cell interconnect may include a third patterned line opening P3in the top electrode layer250. In the particular embodiment illustrated the third patterned line opening P3does not completely extend through a thickness of the conformal transport layer240so that the conformal transport layer can protect the underlying subcell layer220.

FIG. 5Bis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect ofFIG. 5Ain accordance with an embodiment. In the embodiment illustrated, the solar cell module may include a bottom electrode layer210including a plurality of first patterned line openings, a subcell layer220over the bottom electrode layer210, the subcell layer including a plurality of second patterned line openings, a conformal transport layer240over subcell layer and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240. In the embodiment illustrated, a non-metallic intermediate layer230is located between the conformal transport layer240and the subcell layer220, and the non-metallic intermediate layer230laterally surrounds the outside perimeter224of the subcell layer220. Additionally, the conformal transport layer240may also surround an outside perimeter234of the non-metallic intermediate layer230.

Several variations of the embodiments illustrated inFIGS. 5A-5Bare contemplated. For example, referring toFIG. 6A, the third patterned line opening P3may partially or completely extend through any of the top electrode layer250, the conformal transport layer240, and the subcell layer220. As shown, a non-electrically conductive material260can fill the third patterning line opening P3. For example, the non-electrically conductive material260may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer240is interrupted by the third patterned line opening P3. In an embodiment the non-electrically conductive material260and the non-metallic intermediate layer230are formed of the same material.

Another alternative is illustrated inFIG. 6B, where rather than forming a separate non-electrically conductive material in the third patterned line opening P3, the non-metallic intermediate layer230thickness may be offset within the second patterned line opening P2. In this case, the third patterned line opening P3extends through a thickness of the non-metallic intermediate layer230rather than the subcell layer220in order to provide further protection of the subcell layer220to 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 inFIGS. 6A-6B, the third patterned line opening P3may extend through the previously continuous conformal transport layer240.FIGS. 6A-6Billustrate alternatively in which the break is prepared by a non-electrically conductive material260or pre-existing non-metallic intermediate layer230. Alternatively, or additionally, a continuous protective layer may be formed over the entire device stack.FIG. 6Cprovides an additional alternative to that illustrated inFIG. 6B, in which the non-metallic intermediate layer230is underneath the third patterned line opening P3as a precaution, even though the third patterned line opening P3does not extend into the non-metallic intermediate layer230.

Referring now toFIGS. 7-8I,FIG. 7is flow chart illustrating a method of forming the interconnect ofFIG. 5Ain accordance with an embodiment.FIGS. 8A-8Iare schematic cross-sectional side view illustrations of a method of forming the interconnect ofFIG. 5Ain accordance with an embodiment. In the following description, the processing sequence ofFIG. 7is made with regard to the cross-sectional side view illustrations ofFIGS. 8A-8I. In interests of conciseness, and to not overly obscure embodiments the processing sequence variations to for the embodiments illustrated inFIGS. 6A-6Care not separately illustrated, and instead are described together along withFIGS. 7-8I. 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 inFIG. 8Athe processing sequence may begin with a substrate202. Substrate202may be a single or multiple layer substrate, including one or more layers of glass, plastic, or conductive metal foil. The bottom electrode layer210may then be formed on substrate202as illustrated inFIG. 8B. Bottom electrode layer210may be formed of materials such as cadmium stannate, TCOs, including ITO, FTO, IZO, etc. Referring now toFIG. 8C, at operation710a first patterned line opening P1is then formed in the bottom electrode layer210. 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 layer220is then formed over the patterned bottom electrode layer210at operation720, as shown inFIG. 8D. The subcell layer220generally 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 layer220may include a single subcell, or multiple subcells such as with a tandem structure. In accordance with embodiments, the subcell layer220includes one or more absorber layers including a perovskite material. In an embodiment, the subcell layer220includes 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 ABX3, 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 layer220is then patterned to form a second patterned line opening P2at operation730, as illustrated inFIG. 8E. 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 toFIGS. 8F-G, at operation740a non-metallic intermediate layer230is formed along sidewalls222of P2. In the specific embodiment illustrated, the non-metallic intermediate layer230is first applied to fill P2using a printing technique such as ink jet, extrusion, spraying, etc. The non-metallic intermediate layer230is 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 inFIG. 8G, the non-metallic intermediate layer230is patterned to form an opening231that may expose the bottom electrode layer210. For example, this patterning may utilize a mechanical or laser scribing.

In the particular embodiment illustrated inFIG. 8G, opening231substantially aligns with the middle of P2such that lateral thicknesses of the non-metallic intermediate layer230on opposite sidewalls222are substantially the same. However, embodiments are not so limited. For example, in a processing sequence to create the interconnect structure ofFIG. 6BorFIG. 6C, the opening231and P2may be offset, with different lateral thicknesses of the non-metallic intermediate layer230on opposite sidewalls222.

Referring now toFIG. 8H, at operation750a conformal transport layer240is formed over the subcell layer220, on the non-metallic intermediate layer within P2, and over the bottom electrode layer within P2. The conformal transport layer240may be continuous. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 2,2′,7,7′-Tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-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. In an embodiment, the conformal transport layer is less than 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer for the solar cell120. Alternatively, the conformal transport layer may function as a hole transport layer for the solar cell120.

In an embodiment, an AZO containing conformal transport layer240is 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 layer250may then be formed over the conformal transport layer and on the conformal transport layer within P2at operation760as illustrated inFIG. 8I. In a particular embodiment, the top electrode layer250is deposited through a shadow mask to form the third patterned line opening P3during 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 layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc.

In an embodiment scribing is utilized to form P3in the top electrode layer250. In the embodiments illustrated inFIGS. 6B-6C, the non-metallic intermediate layer230is located underneath P3, or P3extends into or completely through the non-metallic intermediate layer230. Either configuration may provide protection for the absorber layer(s). In the embodiment illustrated inFIG. 6A, scribing can be used to form P3partially or completely through any of the top electrode layer250, conformal transport layer240, and subcell layer220. In such an embodiment, P3is partially or fully filled with an insulating material260to 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 toFIGS. 9A-26C. Accordingly, in interest of conciseness, detailed discussion of specific processing techniques and materials selections may not be repeated.

FIG. 9Ais 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 layer210on a substrate202, a first patterned line opening P1in the bottom electrode layer210, a subcell layer220over the bottom electrode layer210and within the first patterned line opening P1, a second patterned line opening P2in the subcell layer220, a non-metallic intermediate layer235along sidewalls of the second patterned line opening P2, a conformal transport layer240over the subcell layer220, on the non-metallic intermediate layer235within the second patterned line opening P2and over the bottom electrode layer210within the second patterned line opening P1, and a top electrode layer250over the conformal transport layer240and on the conformal transport layer240within the second patterned line opening P2. The conformal transport layer240may be continuous. In the embodiment illustrated, the non-metallic intermediate layer235is a thin insulator layer or nucleation layer that is globally formed. In an embodiment, non-metallic intermediate layer235is less than 10 nm thick, such as 1-5 nm thick. As shown, the non-metallic intermediate layer235may physically separate the conformal transport layer240from bottom electrode layer210. In accordance with embodiment, the non-metallic intermediate layer235is formed of a material selected from the group consisting of an insulator, semiconductor, and carbon. The non-metallic intermediate layer235may 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 layer240. In an embodiment, the non-metallic intermediate layer235includes OH groups to help nucleate the growth of a metal oxide containing conformal transport layer240. Ethoxylated polyethyleneimine (PETE) and polyvinyl alcohol (PVA) have such OH groups. The non-metallic intermediate layer235may also be formed of materials such as polyvinyl phenol and polystyrene. In an alternative embodiment, the non-metallic intermediate layer235may be patterned to expose the bottom electrode layer210similarly as non-metallic intermediate layer230previously described.

FIG. 9Bis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect ofFIG. 9Ain accordance with an embodiment. In the embodiment illustrated, the solar cell module may include a bottom electrode layer210including a plurality of first patterned line openings, a subcell layer220over the bottom electrode layer210, the subcell layer including a plurality of second patterned line openings, a conformal transport layer240over subcell layer and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240. In the embodiment illustrated, a non-metallic intermediate layer235is located between the conformal transport layer240and the subcell layer220, and the non-metallic intermediate layer235laterally surrounds the outside perimeter224of the subcell layer220. Additionally, the conformal transport layer240may also surround an outside perimeter238of the non-metallic intermediate layer235.

Referring now toFIGS. 10-11D,FIG. 10is flow chart illustrating a method of forming the interconnect ofFIG. 9Ain accordance with an embodiment.FIGS. 11A-11Dare schematic cross-sectional side view illustrations of a method of forming the interconnect ofFIG. 9Ain accordance with an embodiment. In the following description, the processing sequence ofFIG. 10is made with regard to the cross-sectional side view illustrations ofFIGS. 11A-11D. 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 ofFIG. 7. At operation1010a first patterned line opening P1is formed in the bottom electrode layer210. At operation1020the subcell layer220is formed over the patterned bottom electrode layer210. Referring toFIG. 11Athe subcell layer220is then patterned to form a second patterned line opening P2at operation730. Referring toFIG. 11B, at operation1040a non-metallic intermediate layer235is formed along sidewalls222of P2and over the top surface of the bottom electrode layer210. The non-metallic intermediate layer235may be formed directly on the top surface211of the bottom electrode layer210. Alternatively, the non-metallic intermediate layer235may be patterned similarly as non-metallic intermediate layer230to expose the bottom electrode layer210. In accordance with embodiments, non-metallic intermediate layer235may be a nucleation layer or insulator layer less than 10 nm 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 layer235may be a conformal layer, with thickness less than 10 nm along sidewalls222of P2, and on the top surface211of the bottom electrode layer210. 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 layer235is 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 layer235may 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 layer235is a conformal layer in order to cover the entire surface and aid in nucleation.

Referring now toFIG. 11C, at operation1050a conformal transport layer240is formed over the subcell layer220, on the non-metallic intermediate layer within P2. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell120.

The top electrode layer250may then be formed over the conformal transport layer and on the conformal transport layer within P2at operation1060as illustrated inFIG. 11D. In a particular embodiment, the top electrode layer250is deposited through a shadow mask to form the third patterned line opening P3during 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 layer250includes 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 P3similarly as described and illustrated with regard toFIG. 6A, followed by at least partially filling with a non-electrically conductive material260.

FIG. 12Ais 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 layer210on a substrate202, a first patterned line opening P1in the bottom electrode layer210, a subcell layer220over the bottom electrode layer210and within the first patterned line opening P1, a second patterned line opening P2in the subcell layer220, a non-metallic intermediate layer235along sidewalls of the second patterned line opening P2, a conformal transport layer240over the subcell layer220, on the non-metallic intermediate layer235within the second patterned line opening P2and over the bottom electrode layer210within the second patterned line opening P1, and a top electrode layer250over the conformal transport layer240and on the conformal transport layer240within the second patterned line opening P2. The conformal transport layer240may be continuous. In the embodiment illustrated, P2overlaps P1. Also shown, are the non-metallic intermediate layer230formed along one sidewall222of P2and on the substrate202inside of P1, and the non-metallic intermediate layer230formed along the opposite sidewall222of P2and on the bottom electrode layer210. An opening in the non-metallic intermediate layer230exposes a top surface the bottom electrode layer. The conformal transport layer240of the embodiment illustrated inFIG. 12Amay be in direct contact with the bottom electrode layer210.

FIG. 12Bis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect ofFIG. 12Ain accordance with an embodiment. Similar to the embodiment illustrated inFIG. 5B, the solar cell module may include a bottom electrode layer210including a plurality of first patterned line openings, a subcell layer220over the bottom electrode layer210, the subcell layer including a plurality of second patterned line openings, a conformal transport layer240over subcell layer and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240. In the embodiment illustrated, a non-metallic intermediate layer230is located between the conformal transport layer240and the subcell layer220, and the non-metallic intermediate layer230laterally surrounds the outside perimeter224of the subcell layer220. Additionally, the conformal transport layer240may also surround an outside perimeter234of the non-metallic intermediate layer230.

Several variations of the embodiments illustrated inFIGS. 12A-12Bare contemplated. For example, referring toFIG. 13, the third patterned line opening P3may partially or completely extend through any of the top electrode layer250, the conformal transport layer240, and the subcell layer220. As shown, a non-electrically conductive material260can fill the third patterning line opening P3. For example, the non-electrically conductive material260may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer240is interrupted by the third patterned line opening P3. In an embodiment the non-electrically conductive material260and the non-metallic intermediate layer230are formed of the same material.

Referring now toFIGS. 14-15H,FIG. 14is flow chart illustrating a method of forming the interconnect ofFIG. 12Ain accordance with an embodiment.FIGS. 15A-15Hare schematic cross-sectional side view illustrations of a method of forming the interconnect ofFIG. 12Ain accordance with an embodiment. In the following description, the processing sequence ofFIG. 14is made with regard to the cross-sectional side view illustrations ofFIGS. 15A-15H. 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.

Referring toFIG. 15Aa bottom electrode layer210may first be formed on a substrate202, followed by the formation of subcell layer220as illustrated inFIG. 15B. At operation1410, a first patterned line opening P1is formed through the subcell layer220, and bottom electrode layer210. At operation1420a second patterned line opening P2is formed in the subcell layer220, where P2overlaps P1. P2may be wider than P1. Additionally, P2and P1may share a same sidewall222in the subcell layer220.

Referring now toFIGS. 15E-15F, at operation1430a non-metallic intermediate layer230is formed along sidewalls222of P2. In the specific embodiment illustrated, the non-metallic intermediate layer230is first applied to fill P2using a printing technique such as ink jet, extrusion, spraying, etc. The non-metallic intermediate layer230is 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 inFIG. 15F, the non-metallic intermediate layer230is patterned to form an opening231that may expose the bottom electrode layer210and optionally substrate202. For example, this patterning may utilize laser scribing. In the particular embodiment illustrated inFIG. 15F, opening231substantially aligns with the middle of P2such that lateral thicknesses of the non-metallic intermediate layer230on opposite sidewalls222are substantially the same. However, embodiments are not so limited.

Referring now toFIG. 15G, at operation1440a conformal transport layer240is formed over the subcell layer220, and on the non-metallic intermediate layer230within P2. In an embodiment, the conformal transport layer240is formed on the top surface of the bottom electrode210. The conformal transport layer240may also be formed within P1. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell120.

The top electrode layer250may then be formed over the conformal transport layer and on the conformal transport layer within P2at operation1450as illustrated inFIG. 15H. In a particular embodiment, the top electrode layer250is deposited through a shadow mask to form the third patterned line opening P3during 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 layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In the alternative embodiment illustrated inFIG. 13, scribing could be performed to create P3similarly as described and illustrated with regard toFIG. 6A, followed by at least partially filling with a non-electrically conductive material260.

FIG. 16Ais a schematic cross-sectional side view illustration of an interconnect with a conductive plug in a subcell patterned line opening in accordance with an embodiment. As shown, the solar cell interconnect may include a bottom electrode layer210, a first patterned line opening P1in the bottom electrode layer210, a subcell layer220over the bottom electrode layer, a second patterned line opening P2in the subcell layer220, a conductive plug270within P2, a conformal transport layer240over the subcell layer220and the conductive plug270, a top electrode layer250over the conformal transport layer240, and a third patterned line opening P3in the top electrode layer250. The conformal transport layer240may be continuous. In the embodiment illustrated, P3does not completely extend through a thickness of the conformal transport layer240.

FIG. 16Bis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including the interconnect ofFIG. 16Ain accordance with an embodiment. Similar to the embodiment illustrated inFIG. 5B, the solar cell module may include a bottom electrode layer210including a plurality of first patterned line openings, a subcell layer220over the bottom electrode layer210, the subcell layer including a plurality of second patterned line openings, a conformal transport layer240over subcell layer and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240.

Several variations of the embodiments illustrated inFIGS. 16A-16Bare contemplated. For example, referring toFIG. 17, the third patterned line opening P3may partially or completely extend through any of the top electrode layer250, the conformal transport layer240, and the subcell layer220. As shown, a non-electrically conductive material260can fill the third patterning line opening P3. For example, the non-electrically conductive material260may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer240is interrupted by the third patterned line opening P3.

Referring now toFIGS. 18-19D,FIG. 18is flow chart illustrating a method of forming the interconnect ofFIG. 16Ain accordance with an embodiment.FIGS. 19A-19Dare schematic cross-sectional side view illustrations of a method of forming the interconnect ofFIG. 16Ain accordance with an embodiment. In the following description, the processing sequence ofFIG. 18is made with regard to the cross-sectional side view illustrations ofFIGS. 19A-19D. 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 ofFIG. 7. At operation1810a first patterned line opening P1is formed in the bottom electrode layer210. At operation1820the subcell layer220is formed over the patterned bottom electrode layer210. Referring toFIG. 19Athe subcell layer220is then patterned to form a second patterned line opening P2at operation1830. Referring toFIG. 19B, at operation1040an (electrically) conductive plug270is formed within P2and on the bottom electrode layer210. The conductive plug270may 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 plug270may 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 plug270in accordance with embodiments may only be greater than about 0.001 S/cm due to the short distance of the interconnection based on the thin film thickness in the 0.1-5 μm 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 1-100 S/cm) and ITO nanoparticles. In an embodiment, the conductive plug270includes 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 10-200 nm in an embodiment, but could be AZO, Sb:SnO2, zinc tin oxide, cadmium stannate and could be microparticles with diameters between 0.2-2 μm.

Referring now toFIG. 19C, at operation1850a conformal transport layer240is formed over the subcell layer220and over the electrically conductive plug270within P2. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 150 nm thick, or more specifically less than 50 nm thick such as 10-20 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer to the subcell layer220.

The top electrode layer250may then be formed over the conformal transport layer240at operation1860as illustrated inFIG. 19D. In a particular embodiment, the top electrode layer250is deposited through a shadow mask to form the third patterned line opening P3during 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 layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In an alternative embodiment illustrated inFIG. 17, scribing could be performed to create P3similarly as described and illustrated with regard toFIG. 6A, followed by at least partially filling with a non-electrically conductive material260.

FIG. 20Ais a schematic cross-sectional side view illustration of an interconnect with a conductive plug in a subcell patterned line opening in accordance with an embodiment. As shown, the solar cell interconnect may include a bottom electrode layer210, a first patterned line opening P1in the bottom electrode layer210, a subcell layer220over the bottom electrode layer, a second patterned line opening P2in the subcell layer220, a conductive plug270within P2, a conformal transport layer240over the subcell layer220and the conductive plug270, a top electrode layer250over the conformal transport layer240, and a third patterned line opening P3in the top electrode layer250. The conformal transport layer240may be continuous. P3may not completely extend through a thickness of the conformal transport layer240. In the particular embodiment illustrated P2overlaps P1. Additionally, a non-metallic intermediate layer230may be formed along a single sidewall222of P2. Non-metallic intermediate layer230may be formed of the same materials as the non-metallic intermediate layer230previously described. More specifically, the non-metallic intermediate layer230may be formed along a single sidewall222of P1that is shared with P1. The non-metallic intermediate layer230may be formed within P1. Additionally, P3may optionally overlap P2.

In the particular embodiment illustrated inFIG. 20A, a lateral edge232of the non-metallic intermediate layer230is over the bottom electrode layer210. The lateral edge232may be located elsewhere in accordance with embodiments. For example, the variation illustrated inFIG. 20Bshows lateral edge232located within P1.

FIG. 20Cis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including an interconnect ofFIG. 20A-20Bin accordance with an embodiment. Similar to the embodiment illustrated inFIG. 5B, the solar cell module may include a bottom electrode layer210including a plurality of first patterned line openings, a subcell layer220over the bottom electrode layer210, the subcell layer including a plurality of second patterned line openings, a conformal transport layer240over subcell layer and laterally surrounding an outside perimeter224the subcell layer220, and a patterned top electrode layer250over the conformal transport layer240. In the embodiment illustrated, a non-metallic intermediate layer230is located between the conformal transport layer240and the subcell layer220, and the non-metallic intermediate layer230laterally surrounds the outside perimeter224of the subcell layer220. Additionally, the conformal transport layer240may also surround an outside perimeter284of the non-metallic intermediate layer230.

Several variations of the embodiments illustrated inFIGS. 20A-20Care contemplated. For example, referring toFIG. 21, the third patterned line opening P3may partially or completely extend through any of the top electrode layer250, the conformal transport layer240, and the subcell layer220. As shown, a non-electrically conductive material260can fill the third patterning line opening P3. For example, the non-electrically conductive material260may be a polymer, metal oxide, or nitride material and may function to prevent metal degradation from where the conformal transport layer240is interrupted by the third patterned line opening P3. In an embodiment the non-electrically conductive material260and the non-metallic intermediate layer230are formed of the same material.

Referring now toFIGS. 22-23F,FIG. 22is flow chart illustrating a method of forming the interconnect ofFIG. 19Ain accordance with an embodiment.FIGS. 23A-23Fare schematic cross-sectional side view illustrations of a method of forming the interconnect ofFIG. 20Ain accordance with an embodiment. In the following description, the processing sequence ofFIG. 22is made with regard to the cross-sectional side view illustrations ofFIGS. 23A-23F. 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 ofFIG. 7. At operation2210a first patterned line opening P1is formed in the bottom electrode layer210. At operation2220the subcell layer220is formed over the patterned bottom electrode layer210as shown inFIG. 23A. Referring toFIG. 23Bthe subcell layer220is then patterned to form a second patterned line opening P2at operation2230. Referring toFIG. 23C, at operation2240a non-metallic intermediate layer230is formed along a sidewall222of P2. Non-metallic intermediate layer230may be formed along a single sidewall222in accordance with an embodiment, and as described with regard toFIG. 20A. In an embodiment, non-metallic intermediate layer230is a polymer material such as, but not limited to, poly(methyl methacrylate) (PMMA), poly(vinyl alcohol) (PVA), and polystyrene. Non-metallic intermediate layer230may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. In an embodiment, opening281exists between a sidewall232of the non-metallic intermediate layer230and a sidewall222of P2. Opening281may expose the bottom electrode210.

Referring now toFIG. 23D, at operation2250a conductive plug270is formed within P2, or more specifically within opening281within P2. Conductive plug20may fill opening281between the non-metallic intermediate layer230and the sidewall222P2that is laterally opposite the sidewall222which is covered by non-metallic intermediate layer230. In an embodiment, conductive plug270is in contact with the bottom electrode layer210. Conductive plug270may optionally be formed over the non-metallic intermediate layer230. The conductive plug270may 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 plug270may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. so that further patterning is not necessary.

Referring now toFIG. 23E, at operation2260a conformal transport layer240is formed over the subcell layer220and over the electrically conductive plug270within P2. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell120.

The top electrode layer250may then be formed over the conformal transport layer240at operation2270as illustrated inFIG. 23F. In a particular embodiment, the top electrode layer250is deposited through a shadow mask to form the third patterned line opening P3during 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 layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc. In an alternative embodiment illustrated inFIG. 21, scribing could be performed to create P3similarly as described and illustrated with regard toFIG. 6A, followed by at least partially filling with a non-electrically conductive material260.

FIGS. 24A-24Bare schematic cross-sectional side view illustrations of an interconnect with a printed non-metallic intermediate layer and conductive plug within a subcell patterned line opening in accordance with an embodiment.FIG. 24Cis a schematic cross-sectional side view illustration of edge encapsulation of a solar cell module including an interconnect ofFIG. 24A-24Bin accordance with an embodiment. As shown, the solar cell interconnect may include a bottom electrode layer210, a first patterned line opening P1in the bottom electrode layer, a subcell layer220over the bottom electrode layer210, a conformal transport layer240over the subcell layer220, a top electrode layer250over the conformal transport layer240, and a second patterned line opening P2through the top electrode layer250, the conformal transport layer240and the subcell layer220. A conductive plug270is formed within the second patterned line opening P2to make electrical connection between the top electrode layer250of one cell and the bottom electrode layer210of an adjacent cell. The second patterned line opening P2may overlap the first patented line opening P1. For example, P2may completely overlap P1and be wider than P1.

The conformal transport layer240may be a continuous layer prior to patterning of P2. Referring toFIG. 24C, the conformal transport layer240may laterally surround the outside perimeter224of the subcell layer220, and optionally outside perimeter214of the bottom electrode layer210. The solar cell interconnect may further include a non-metallic intermediate layer230along one or more sidewalls of the second patterned line opening P2. For example, this may be sidewalls222of the subcell layer220, as well as sidewalls of the conformal transport layer240and top electrode layer250. In the embodiment illustrated inFIG. 24Aa third patterned line opening P3is formed in the conductive plug270within the second line opening P2. The third patterned line opening P3may expose the bottom electrode layer210. In the embodiment illustrated inFIG. 24Bthe non-metallic intermediate layer230is formed on both laterally opposite sidewalls of the second patterned line opening P2, and a third patterned line opening P3is formed in the non-metallic intermediate layer230. The third patterned line opening P3extends into the second patterned line opening P2, and the conductive plug20fills the third patterned line opening P3in the non-metallic intermediate layer. In accordance with embodiments, the top electrode layer250ofFIGS. 24A-24Ccan include metal layer, and the bottom electrode layer210can include a transparent material.

Referring now toFIGS. 25-26C,FIG. 25is flow chart illustrating a method of forming the interconnects ofFIGS. 24A-24Bin accordance with embodiments.FIGS. 26A-26Care schematic cross-sectional side view illustrations of a method of forming the interconnects ofFIG. 24A-24Bin accordance with embodiments. In the following description, the processing sequence ofFIG. 25is made with regard to the cross-sectional side view illustrations ofFIGS. 26A-26C. 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 ofFIG. 7. At operation2510a first patterned line opening P1is formed in the bottom electrode layer210. At operation2520the subcell layer220is formed over the patterned bottom electrode layer210. At operation2530a conformal transport layer240is formed over the subcell layer, and at operation2540a top electrode layer250is formed over the conformal transport layer240as illustrated inFIG. 26A. The conformal transport layer240may function to encapsulate and protect the subcell layer220, 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 1,000 nm thick, such as less than 150 nm thick, or more specifically less than 50 nm thick such as 10-40 nm 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 layer240may be characterized by a resistivity greater than 0.1 ohm·cm. In an embodiment, the conformal transport layer also functions as an electron transport layer or hole transport layer for a solar cell120. The top electrode layer250may be formed using suitable deposition technique such as evaporation, sputter, printing, and spraying. In an embodiment, the top electrode layer250includes one or more metal layers, such as Ag, Cu, Al, Au, etc.

Referring now toFIG. 26Bat operation2550a second patterned line opening P2is then formed through the top electrode layer250, the conformal transport layer240, and the subcell layer220. As shown, the P2may overlap P1, and may be wider than P1. Formation of P2may also remove any subcell layer220material from within P1.

A non-metallic intermediate layer230may then be formed along one, or both, sidewalls of P2as shown inFIG. 26C. Non-metallic intermediate layer230may be formed of the same materials as the non-metallic intermediate layer230previously described. Non-metallic intermediate layer230may be formed using a suitable printing technique such as ink jet, extrusion, spraying, etc. In an embodiment such asFIG. 24B, a third patterned line opening P3may be formed in the non-metallic intermediate layer230. 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 layer230. In an embodiment such asFIG. 24A, the non-metallic intermediate layer230may be formed along a single sidewall of P2. In both configurations the non-metallic intermediate layer230can insulate the top electrode layer250from the bottom electrode layer210after formation of the plug270.

Referring toFIG. 26C, at operation2570an (electrically) conductive plug270is formed within P2and on the bottom electrode layer210. In the embodiment ofFIG. 24A, it is not necessary to further pattern the conductive plug270. In the embodiment ofFIG. 24B, a third patterned line opening P3may be formed in the conductive plug270to prevent shorting across the top electrode layer250.

The conductive plug270may 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 plug270may 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 plug270in accordance with embodiments may only be greater than about 0.001 S/cm due to the short distance of the interconnection based on the thin film thickness in the 0.1-5 μm 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 1-100 S/cm) and ITO nanoparticles. In an embodiment, the conductive plug270includes 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 10-200 nm in an embodiment, but could be AZO, Sb:SnO2, zinc tin oxide, cadmium stannate and could be microparticles with diameters between 0.2-2 μm.

In utilizing the various aspects of the embodiments, it would become apparent to one skilled in the art that combinations or variations of the above embodiments are possible for forming a solar cell module and stable interconnect. Although the embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the specific features or acts described. The specific features and acts disclosed are instead to be understood as embodiments of the claims useful for illustration.