DCT

1:25-cv-00223

First Solar Inc v. JinkoSolar Holding Co Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:25-cv-00223, D. Del., 02/25/2025
  • Venue Allegations: Plaintiff alleges venue is proper in the District of Delaware because several JinkoSolar U.S. entities are incorporated there, and the collective JinkoSolar enterprise purposefully directs its activities to Delaware, including placing the accused products into the stream of commerce with the knowledge and intent that they be sold in the state.
  • Core Dispute: Plaintiff alleges that Defendant’s TOPCon solar cells are manufactured overseas using a process that infringes a U.S. patent on manufacturing methods, and that these cells and the modules containing them are then unlawfully imported into and sold in the U.S.
  • Technical Context: The lawsuit concerns Tunnel Oxide Passivated Contact (TOPCon) technology, a critical innovation in the photovoltaic industry for producing high-efficiency N-type solar cells that minimize energy loss from electron recombination.
  • Key Procedural History: The complaint alleges that JinkoSolar was on notice of its infringement at least as of September 26, 2024, when First Solar sent a notice letter. This allegation of pre-suit knowledge forms the basis for a claim of willful infringement.

Case Timeline

Date Event
2009-04-21 ’074 Patent Priority Date
2015-09-08 ’074 Patent Issue Date
2024-07-19 Approximate date of First Solar's public announcement of its TOPCon patent ownership
2024-09-26 First Solar sends written notice of infringement of the ’074 Patent to JinkoSolar
2025-02-25 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,130,074 - High-Efficiency Solar Cell Structures and Methods of Manufacture

  • Patent Identification: U.S. Patent No. 9,130,074, High-Efficiency Solar Cell Structures and Methods of Manufacture, issued September 8, 2015 (’074 Patent).

The Invention Explained

  • Problem Addressed: The patent seeks to create highly efficient solar cells (over 20%) that can be manufactured in a cost-effective manner, overcoming the complexity often associated with such cells (’074 Patent, col. 1:35-42). A key technical challenge in solar cell efficiency is the "recombination" of free electrons, particularly at the silicon substrate's surfaces, which reduces the electrical current that can be harvested (Compl. ¶63).
  • The Patented Solution: The invention is a method for fabricating a solar cell by depositing an amorphous interface passivation layer on a silicon wafer, followed by a doped conductive layer. The entire assembly is then subjected to a high-temperature thermal treatment (above 500°C). This heat treatment simultaneously crystallizes the conductive layer and, critically, causes the dopant to diffuse through the thin passivation layer. This diffused dopant creates highly conductive, "shortened" pathways for charge carriers to travel to the electrodes, reducing recombination and increasing efficiency (’074 Patent, Abstract; col. 19:14-35). Figure 5 illustrates the more direct, curved path that charge carriers can take in such a structure, as compared to the less efficient path shown in Figure 4 (’074 Patent, Figs. 4-5).
  • Technical Importance: This method provides an efficient way to create a passivated contact structure (the basis of TOPCon technology) that improves charge carrier collection without requiring complex, costly steps like etching or precisely aligning separate contact openings (’074 Patent, col. 2:19-24; Compl. ¶75).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2, 4, and 8 (Compl. ¶¶ 88-91).
  • The essential elements of independent claim 1 include:
    • Providing a wafer as a central substrate.
    • Depositing or growing at least one amorphous interface passivation layer over the substrate.
    • Depositing at least one conductive and passivating layer (containing a dopant) on the interface passivation layer.
    • Applying a thermal treatment of about 500°C or higher, which crystallizes the conductive layer and facilitates diffusion of the dopant through the interface passivation layer.
    • Providing metallization (electrodes) that directly contacts the conductive and passivating layer, where the diffused dopant results in "shortened charge carrier flow paths" between the substrate and the electrodes.

III. The Accused Instrumentality

Product Identification

  • The accused instrumentalities are JinkoSolar’s TOPCon solar cells and the solar modules that incorporate them, including products from the "Eagle," "Tiger Neo," and "Neo Green" lines (Compl. ¶76).

Functionality and Market Context

  • The accused products are N-type TOPCon solar modules, which JinkoSolar markets as having high efficiency, in part due to their cell technology (Compl. ¶¶ 78, 81, 85). The complaint alleges these products are made overseas using a process that practices the steps of the ’074 Patent (Compl. ¶8). A key technical feature highlighted in the complaint is a layered cell structure comprising an "n-Silicon substrate" (the wafer), a "Tunneling layer" (the interface passivation layer), and an "n+ Poly" layer (the conductive and passivating layer) (Compl. ¶¶ 93-95).
  • The complaint presents a product datasheet for the "Tiger Neo 66HL4M-BDV" module, which explicitly states that it utilizes "N-Type modules with Tunnel Oxide Passivating Contacts (TOPcon) technology" (Compl. ¶83, p. 45).
  • The complaint alleges that JinkoSolar is a major global manufacturer of solar modules and has deployed "more than 28 GW" of solar products in the U.S. and Canada, positioning the accused products as commercially significant (Compl. ¶¶ 7, 39).

IV. Analysis of Infringement Allegations

  • Claim Chart Summary:

’074 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A method of fabricating a solar cell comprising: providing a wafer as a central substrate; JinkoSolar uses a silicon wafer, identified as the "n-Silicon substrate" in its technical diagrams, as the central substrate for its TOPCon cells. ¶93 col. 19:16-17
depositing or growing at least one amorphous interface passivation layer over the substrate; JinkoSolar deposits an amorphous interface passivation layer, which it refers to as the "Tunneling layer," over the silicon substrate. ¶94 col. 19:18-20
depositing at least one conductive and passivating layer on the at least one interface passivation layer, the at least one conductive and passivating layer comprising a dopant; JinkoSolar deposits a conductive and passivating polysilicon layer, which it refers to as the "n+ Poly" layer, on the tunneling layer. This layer is doped with phosphorus, an N-type dopant. ¶95 col. 19:21-24
providing thermal treatment at a temperature of about 500° C. or higher...facilitating diffusion of the dopant...through the at least one interface passivation layer; JinkoSolar applies a thermal treatment that facilitates the diffusion of the phosphorus dopant from the "n+ Poly" layer, through the "tunneling layer," and into the "n-Silicon substrate." The complaint provides a graph showing phosphorus concentration versus depth, arguing this diffusion profile necessitates a thermal treatment above 500° C. ¶¶96-98 col. 19:25-31
providing metallization as electrodes which directly contact the at least one conductive and passivating layer...wherein the dopant diffused through the...interface passivation layer provides shortened charge carrier flow paths... JinkoSolar provides metal electrodes that directly contact the "n+ Poly" layer. The diffused phosphorus is alleged to create higher conductivity near the substrate surface, resulting in the "shortened charge carrier flow paths" taught by the patent. The complaint provides a graph from testing of JinkoSolar's cells, which shows the amount of phosphorus diffused from the conductive layer into the central substrate (Compl. p. 55). ¶¶99-100 col. 19:32-42
  • Identified Points of Contention:
    • Scope Questions: A potential dispute may arise over the term "about 500° C." While the complaint alleges the observed dopant diffusion requires such a temperature, JinkoSolar may argue its manufacturing process uses a temperature outside the scope of this term.
    • Technical Questions: A primary technical question will be whether the phosphorus distribution shown in the complaint's graph (Compl. p. 55) is uniquely attributable to the claimed method. JinkoSolar may contend that a different, non-infringing process could produce a similar chemical profile. Further, the allegation of "direct contact" by the electrodes may be challenged if JinkoSolar can show the presence of any intervening, non-conductive material not accounted for in the complaint’s diagrams.

V. Key Claim Terms for Construction

  • The Term: "amorphous interface passivation layer"

  • Context and Importance: This term is critical because the claim requires the initial deposited layer to be "amorphous," which is then subjected to a thermal treatment that causes dopant diffusion through it. The infringement allegation hinges on identifying JinkoSolar's "tunneling layer" as meeting this description (Compl. ¶94). Practitioners may focus on this term because the physical properties and behavior of the layer during heat treatment depend on its amorphous state.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The patent does not appear to provide an explicit definition, suggesting the term should be given its plain and ordinary meaning in the art. The specification discusses various materials that can form such a layer, such as "silicon oxide, silicon nitride, intrinsic amorphous silicon," implying a focus on function rather than a single chemical or structural formula (’074 Patent, col. 6:58-62).
    • Evidence for a Narrower Interpretation: A party could argue that the term should be limited by the context of the embodiments, for example, to layers that are "deposited or grown with methods such as PECVD, APCVD, LPCVD, PVD, plating etc." (’074 Patent, col. 22:55-58), potentially excluding layers formed by other means or with different structural characteristics.

  • The Term: "shortened charge carrier flow paths"

  • Context and Importance: This is a functional limitation describing the result of the claimed process. Proving infringement requires showing that the accused method achieves this specific outcome (Compl. ¶100). The definition of "shortened" is relative and will be a key point of dispute.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The patent contrasts the "shortened" path in Figure 5 with the less efficient path in Figure 4, which involves significant lateral travel through a resistive layer. A broad interpretation would read "shortened" to mean any path that is consequently more direct and vertical due to the increased conductivity from dopant diffusion, as conceptually shown in Figure 5 (’074 Patent, col. 16:51-68).
    • Evidence for a Narrower Interpretation: A party could argue that "shortened" implies a specific, quantifiable improvement in conductivity or a path geometry that is measurably distinct from a defined baseline. The patent's explanation relies on a comparison where the alternative is flow through a "highly resistive" emitter layer; a defendant could argue its product's baseline characteristics are different, making the comparison in the patent inapplicable.

VI. Other Allegations

  • Indirect Infringement: The primary theory of liability is infringement under 35 U.S.C. § 271(g), which prohibits the importation, sale, or use of a product made abroad by a process patented in the U.S. (Compl. ¶104). The complaint also alleges induced infringement under § 271(b), stating that the JinkoSolar entities induce their subsidiaries, distributors, and customers to infringe by importing, selling, and using the accused products through actions such as advertising, providing technical manuals, and establishing U.S. distribution channels (Compl. ¶¶ 105-106).
  • Willful Infringement: The complaint alleges JinkoSolar’s infringement is willful and deliberate. This is based on alleged pre-suit knowledge stemming from a First Solar public announcement in July 2024 and a specific written notice of infringement sent to JinkoSolar on September 26, 2024 (Compl. ¶¶ 107, 109).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A core issue will be one of evidentiary proof: Does the complaint's chemical analysis, particularly the phosphorus diffusion graph, conclusively establish that JinkoSolar's overseas process practices the specific thermal treatment and dopant diffusion steps required by Claim 1? The case may turn on whether JinkoSolar can present a plausible, non-infringing explanation for the observed chemical profile of its cells.
  • A second key question will be one of functional interpretation: How will the court construe the relative term "shortened charge carrier flow paths"? The dispute will likely involve a battle of expert testimony to determine if the electrical behavior within the accused cells meets the functional requirements described and illustrated in the patent.
  • Finally, a significant procedural question will be one of enterprise liability: Given the complex corporate structure spanning multiple countries, can First Solar persuade the court to treat the various JinkoSolar defendants as a single, coordinated enterprise for the purposes of jurisdiction and infringement liability, particularly under the provisions of 35 U.S.C. § 271(g)?