Tandem Solar Cell Interconnection Patents: Leaders & White Space 2026
- Filing peaked in 2021 at 19 families, then eased back toward the 2022 midpoint of 11 — this is a maturing claim space, not an accelerating one.
- H01L carries 130 of 149 records, but H10K organic-semiconductor claims already touch 41 of them, showing interconnection layers spilling into OLED-adjacent chemistry.
- US filings (77) outnumber EPO (42) more than 1.8:1, with India's 12 filings signalling a manufacturing-side interest that the US/EU totals alone would miss.
What this landscape covers
Tandem solar cell interconnection is the plumbing that makes a multijunction device work as one cell rather than two: the tunnel junction or recombination layer that lets current pass between sub-cells with minimal optical and resistive loss. This landscape isolates 149 patent families that combine tandem or multijunction solar cell claims with interconnection-specific language — tunnel junction, interconnecting layer, recombination junction, cell interconnection — filtered to the IPC classes that cover heterojunction and multijunction device structure.
Because publication lags filing by roughly 18 months, the 2025-2026 figures in the trend chart are necessarily incomplete; the 2021 peak and the 2022 midpoint are the more reliable read on where activity has actually settled.
Filing trend and technology composition
Two views of the same 149 families: how filing activity has moved year over year, and which IPC subclasses the claims actually sit in.
A peak, then a plateau
Filings rose from 7 in 2017 to a peak of 19 in 2021, then declined toward 11 at the 2022 midpoint. Read this as a claim space that filled in quickly around a known device architecture, rather than one still opening up — new entrants now have to design around a denser prior-art base than filers did in 2017-2019.
H01L dominates, but H10K is not noise
H01L (semiconductor devices) covers 130 of 149 records, confirming this is fundamentally a device-structure claim space. H10K's 41 records — nearly a third of the total — show organic-semiconductor and OLED-derived interconnecting-layer chemistry crossing into tandem solar claims, a signal worth tracking for anyone assuming this is purely a silicon-and-perovskite question.
Shares are the percentage of the 149 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Tandem Solar Cell Interconnection with Eureka
This page is one run against one query. Ask Eureka your own question about tandem solar cell interconnection and every answer comes back with the patent numbers behind it.
Try EurekaThe prior art doing the most citation work
US20160163904A1 — 2-terminal metal halide semiconductor/c-silicon multijunction solar cell with tunnel junction
A 2-terminal multi-junction solar cell using a thin-film metal halide (perovskite) semiconductor as the top cell and crystalline silicon as the bottom cell, integrated through a tunnel junction. The abstract specifies the perovskite as an AM(IxH1-x)3 structure with a defined cation, metal and halide range, and describes the tunnel junction as the element enabling series integration of the two cell materials.Filed by Stanford's Board of Trustees; the most-cited record in this corpus at 65 citations, and the natural reference point for anyone assessing freedom to operate on 2-terminal perovskite-silicon tunnel junction claims.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20160163904A1 | 2-terminal metal halide semiconductor/c-silicon multijunction solar cell with tunnel junction | 65 |
| 2 | US20140182667A1 | Multijunction solar cell with low band gap absorbing layer in the middle cell | 61 |
| 3 | US4292461A | Amorphous-crystalline tandem solar cell | 45 |
| 4 | US20150207011A1 | Multi-junction photovoltaic cells and methods for forming the same | 34 |
| 5 | US20170133542A1 | Multijunction solar cell assemblies for space applications | 32 |
| 6 | US20200212243A1 | Method for manufacturing perovskite silicon tandem solar cell | 30 |
| 7 | US20170222066A1 | Multijunction metamorphic solar cell for space applications | 22 |
| 8 | US9287431B2 | Superstrate sub-cell voltage-matched multijunction solar cells | 21 |
| 9 | EP1798777A2 | Reduced band gap absorber for solar cells | 21 |
| 10 | US20130174896A1 | Tandem solar cell using a silicon microwire array and amorphous silicon photovoltaic layer | 20 |
Citation counts favour older filings simply because they have had more time to accumulate them; treat this table as a map of influential prior art, not a ranking of current relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three patterns in this dataset matter more than the headline counts.
US filing leads by nearly 2:1
United States filings (77) outnumber European filings (42) by a wide margin, with India's 12 filings the next largest bloc. A US-first filing strategy still dominates this space, but India's presence — well ahead of Japan's 3 — suggests manufacturing-side patenting activity that a US/EU-only competitor scan would miss entirely.
Interconnection claims are not silicon-only
Close to a third of records classify under H10K (organic semiconductors), alongside smaller but real footprints in H01G (capacitors, 9), C09D (coatings, 2) and C22C (alloys, 2). Interconnecting-layer chemistry is being claimed from multiple material-science angles, not just from within classical PV device structure.
The rush has already happened
Filing activity peaked in 2021 and has since eased toward the 2022 midpoint of 11 per year. New entrants are filing into a denser prior-art landscape than existed even three years earlier, which raises the bar for a defensible first claim on tunnel junction or recombination layer structure.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to tandem solar cell interconnection, with the prior art for and against each one.
Who is active, and where the claim space is still open
Assignee activity in this corpus is not concentrated behind a single dominant filer; recent-year momentum data shows several established names — including large industrials and a public research organisation — recording zero filings in the latest year, consistent with the post-2021 plateau.
Research institutions anchor the foundational claims
The most-cited record in this corpus, US20160163904A1, comes from Stanford's Board of Trustees, and university and public-research assignees appear repeatedly among the co-assignee pairs — a pattern typical of a technology still transitioning from lab demonstration to manufacturing scale.
French research consortium co-filing stands out
The strongest co-assignee links in this dataset all involve the same French industrial-gas research entity paired separately with a national utility, a national research centre and a polytechnic institute, each at 5 shared families — a tight, France-centred collaboration cluster rather than a broad industry consortium.
Several established filers have gone quiet
Large industrials and at least one major research organisation show zero filings in the most recent year tracked. Given the 18-month publication lag, this may partly reflect filings not yet public rather than genuine exit — but it is consistent with the broader plateau since 2021.
| Assignee | Recent year | YoY |
|---|---|---|
| Soitec | 0 | — |
| The Boeing Company | 0 | — |
| LG Electronics | 0 | — |
| CHAUDHARI ASHOK | 0 | — |
| Netherlands Organisation for Applied Scientific Research (TNO) | 0 | — |
| International Business Machines Corporation (IBM) | 0 | — |
| The Board of Trustees of the Leland Stanford Junior University | 0 | — |
| L'Air Liquide, Société Anonyme pour l'Étude et l'Exploitation des Procédés Georges Claude | 0 | — |
Where to take this
The dataset points to specific next questions rather than a single conclusion.
Check freedom to operate against the cited core
Any 2-terminal perovskite-silicon tunnel junction design should be checked against the most-cited records in this corpus before further development, since those claims have already absorbed six-plus years of citation activity.
Run a freedom-to-operate check in EurekaTrack the H10K crossover
Organic-semiconductor classifications now touch nearly a third of this corpus; monitoring H10K filings specifically may surface interconnecting-layer approaches that a PV-only search misses.
Set up IPC-based monitoring in EurekaReassess India's filing role
India's 12 filings, ahead of Japan and WIPO PCT filings combined, suggest a manufacturing or licensing angle worth investigating on its own terms.
Explore assignee activity in EurekaCommon questions on tandem solar cell interconnection patents
A tunnel junction is the thin, heavily-doped semiconductor interface that connects two solar sub-cells so current can pass between them with minimal voltage loss, effectively letting a tandem device operate as one series-connected cell. It is patented separately from the overall tandem architecture because its doping profile, material composition and thickness are independently novel and directly determine how much efficiency the finished device loses to resistive and optical loss. This dataset filters specifically for that language — tunnel junction, recombination junction, interconnecting layer — rather than for tandem cell claims generally, which is why the corpus is 149 families rather than a much larger tandem-PV set.
Citation counts in this corpus point to Stanford's Board of Trustees as holding the most-cited record, US20160163904A1, covering a 2-terminal metal halide/crystalline-silicon multijunction cell with a tunnel junction. Older filings such as US4292461A on amorphous-crystalline tandem cells also carry high citation counts simply because they have had decades to accumulate them. Citation leadership should be read as a marker of foundational influence rather than current commercial control, since recent high-value filings have not yet had time to be cited as heavily.
No — filing activity peaked in 2021 at 19 families and had declined to 11 by the 2022 midpoint, indicating a plateau rather than continued growth. Because publication lags filing by roughly 18 months, the 2025-2026 figures in any trend chart will understate true recent activity, but the shape of the curve through 2022 is a reliable signal that this claim space filled in quickly after an initial wave of filing. New entrants should expect denser prior art than filers faced in 2017-2019.
The United States leads with 77 filings in this dataset, followed by the European Patent Office at 42, then India at 12, WIPO PCT filings at 8, Japan at 3 and Austria at 1. The nearly 2:1 US-to-EPO ratio suggests a US-centric filing strategy is still standard for this technology, while India's relatively strong showing — ahead of Japan and PCT filings — points to manufacturing-side patenting interest worth investigating separately from the US/EU competitive picture.
The core H01L device-structure claims around tunnel junctions are dense, but smaller IPC footprints in alloys (C22C), coatings (C09D) and nanostructured interfaces (B82Y) suggest under-claimed angles on interconnect composition, passivation and interface engineering. Four-terminal mechanically-stacked interconnection approaches also appear thinner than two-terminal tunnel junction claims in this corpus. Anyone filing new claims should check these adjacent branches specifically, since the core 2-terminal tunnel junction claim space is already occupied by highly-cited prior art.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.