Tandem Solar Cell Transport Layer Patents: Leaders & Trends 2026
- Filing has cooled since its 2023 peak of 19. 2026 counts sit at 3, though publication lag means the last 18 months are undercounted.
- The United States dominates filing venues. 53 of 114 records were filed there, more than EPO, WIPO, Korea, India and China combined.
- Momentum is thinning even among active filers. Recent-year assignee activity shows single-digit counts and year-on-year drops of 88% to 100% at several leading names.
What this landscape covers
This dataset tracks 114 patent families claiming charge transport layer engineering inside tandem and multijunction solar cells — electron transport layers, hole transport layers and charge-selective contacts specifically, rather than tandem cell architecture in general. The search combines tandem/perovskite-silicon/multijunction cell language with transport-layer claim terms and IPC codes spanning organic semiconductor, silicon device and photovoltaic classifications, so it captures the interface engineering rather than absorber chemistry alone.
Records run from 2015 through a 2026-07-31 cut-off. Because publication typically trails filing by around 18 months, the counts for 2025 and 2026 understate actual filing activity and should be read as provisional.
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Filing trend and technology composition
Two views of the same 114-family set: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in.
A peak in 2023, then a pullback
Filings rose from 9 in 2017 to a high of 19 in 2023, roughly doubling over that stretch, then declined toward single digits by 2026. A midpoint reading of 11 in 2022 confirms the growth phase had already flattened before the peak, consistent with a technology whose core claim positions were staked out early rather than still expanding.
Organic semiconductor and silicon device codes dominate
H10K (organic semiconductors, including OLED-adjacent charge transport art) covers 88 of 114 records and H01L (semiconductor devices) covers 64, reflecting that most transport-layer claims are drafted as device or materials claims rather than as dedicated photovoltaic claims. H10F and H02S, the classifications specific to photovoltaic and solar power devices, appear in only 17 and 2 records respectively — a sign that transport-layer innovation in this space is still largely claimed through general semiconductor and organic-electronics language.
Shares are the percentage of the 114 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 Charge Transport Layer with Eureka
This page is one run against one query. Ask Eureka your own question about tandem solar cell charge transport layer and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a representative filing
US12125931B2 — Tandem Solar Cell (Beijing ZenithNano Technology, 2024-10-22)
The patent claims a tandem solar cell built around a light-absorbing layer group flanked by paired electron and hole transport layer groups, joined through a heterojunction layer group whose own electron- and hole-transport sides connect the two sub-cells, with a reflection layer positioned to redirect sunlight back through the absorbing stack.The structure is notable for stacking two electron transport layers and two hole transport layers across the tunnel/heterojunction interface rather than a single ETL/HTL pair per sub-cell.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20160163904A1 | 2-terminal metal halide semiconductor/c-silicon multijunction solar cell with tunnel junction | 65 |
| 2 | US20180019358A1 | Tandem solar cell, tandem solar cell module comprising the same, and method for manufacturing thereof | 55 |
| 3 | US20170271622A1 | High efficiency thin film tandem solar cells and other semiconductor devices | 39 |
| 4 | US20200212243A1 | Method for manufacturing perovskite silicon tandem solar cell | 30 |
| 5 | WO2016090179A1 | 2-terminal metal halide semiconductor/c-silicon multijunction solar cell with tunnel junction | 15 |
| 6 | US20190181290A1 | Perovskite solar cell and tandem solar cell | 12 |
| 7 | US20220085226A1 | Four-terminal tandem solar cell | 11 |
| 8 | US20220209039A1 | Tandem solar cell | 11 |
| 9 | KR1020190010197A | Perovskite solar cell and tandem solar cell including the same | 10 |
| 10 | WO2019200327A1 | Highly efficient perovskite/cu(in, ga)se 2 tandem solar cell | 8 |
Citation counts accumulate over time and favour earlier filings; a low count on a recent record does not mean it is unimportant.
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Three patterns stand out once filing venue, IPC composition and citation concentration are read together.
The US is the primary filing venue by a wide margin
With EPO at 29 and WIPO PCT filings at 12, the US alone accounts for nearly half of all records. South Korea (11), India (6) and China (1) trail well behind, suggesting enforcement and licensing exposure concentrates heavily in US jurisdiction for this claim space.
Influence sits with a small set of early 2-terminal tunnel-junction filings
The two most-cited records both describe 2-terminal metal halide/c-silicon multijunction cells with a tunnel junction, filed as US and WIPO counterparts of the same family. Citation counts of this scale in a 114-record corpus indicate these documents shaped much of the downstream drafting language, not that the underlying technology is still the frontier.
Even active filers are pulling back
Assignees with the most recent-year activity show one filing in the latest year and year-on-year declines as steep as -100% among names that were filing multiple records annually a few years prior. No assignee in the momentum data is currently scaling filings upward.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to tandem solar cell charge transport layer, with the prior art for and against each one.
Who holds claim space, and where it is thin
Assignee activity is fragmented rather than concentrated in a single dominant filer, and co-assignment patterns point to a handful of corporate-group and university collaborations rather than broad industry alliances.
Collaboration is mostly intra-group
The strongest co-assignee pairing links two entities within the same Chinese solar manufacturing group, filing 4 records together; a university pairing between MIT and Stanford's board of trustees appears in 3 records, and a second intra-group Chinese pairing appears in 2.
No assignee is currently scaling
Assignees with any latest-year activity show only 1 record each, and several established filers show 0 in the latest year with steep prior-year declines. This is consistent with a maturing claim landscape rather than a growth phase.
A modest, fragmented corpus
At 114 families across a decade, this is a narrow but technically specific slice of tandem cell patenting. No single assignee's family count approaches a dominant share of the total, leaving room for a well-drafted entrant to stake out a defensible position in specific sub-areas.
| Assignee | Recent year | YoY |
|---|---|---|
| Hanwha Solutions Corporation | 1 | -88% |
| Swift Solar Inc. | 1 | — |
| LG Electronics | 0 | — |
| Zhejiang JinkoSolar Co., Ltd. | 0 | -100% |
| King Fahd University of Petroleum and Minerals | 0 | — |
| CHAUDHARI ASHOK | 0 | — |
| LONGi Green Energy Technology Co., Ltd. | 0 | — |
| JinkoSolar Co., Ltd. | 0 | -100% |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, licensing or new filing strategy.
Map the tunnel-junction citation cluster
The two highest-cited records both describe 2-terminal metal halide/c-silicon tunnel-junction structures. Anyone drafting in this space should trace forward and backward citations from these specific families before finalizing claim scope.
Explore citation network in EurekaStress-test the under-claimed branches
Dual-transport-layer stacking and transport-plus-reflection-layer integration show thin filing density relative to the core corpus. A structured novelty search against these branches specifically, rather than the topic as a whole, is likely to surface real white space.
Run a white space search in EurekaWatch for the 18-month reporting lag
The 2025-2026 decline in filing counts partly reflects publication lag rather than an actual drop in activity. Re-pull the trend in two to three quarters before concluding the field has cooled.
Set up monitoring in EurekaFrequently asked questions
A charge transport layer is the material layer that selectively conducts either electrons or holes away from the light-absorbing layer while blocking the opposite carrier, commonly called an electron transport layer (ETL) or hole transport layer (HTL). In tandem cells these layers also appear at the interconnecting junction between sub-cells, sometimes described as charge-selective contacts. This dataset specifically searches for claims naming these layers or their engineering, rather than tandem cell architecture claims that do not address the transport layer itself.
Filing volume rose from 9 records in 2017 to a peak of 19 in 2023, then fell toward single digits by 2026. Part of that apparent decline is a data artefact: patent publication typically lags filing by around 18 months, so 2025 and 2026 figures will rise as more applications publish. The genuine slowdown likely reflects that core ETL/HTL architectures for tandem cells were substantially claimed during the 2020-2023 filing wave, pushing new applicants toward narrower or adjacent claim territory.
The United States is the dominant receiving office in this dataset with 53 of 114 records, well ahead of the European Patent Office at 29 and WIPO PCT filings at 12. South Korea, India and China show smaller counts. A freedom-to-operate search that covers US-filed families first will capture the largest share of enforceable claim scope, but EPO coverage should not be skipped given its close second position.
Not necessarily. The most-cited records in this dataset are early 2-terminal metal halide/c-silicon multijunction filings with tunnel junctions, and citation counts accumulate over time, so older documents mechanically collect more citations regardless of current commercial relevance. Citation rank is best read as a measure of how much subsequent drafting language and prior-art searching referenced a given filing, not as a signal that its specific technical approach is where new investment is concentrated today.
IPC composition shows most claims routed through general semiconductor codes (H10K, H01L) rather than photovoltaic-specific codes (H10F, H02S), which are comparatively thin at 17 and 2 records. Sub-areas such as dual electron/hole transport layer stacking across heterojunction interfaces, transport-layer integration with reflection layers, and non-halide hole transport materials show lower filing density relative to the core corpus, making them reasonable starting points for a more targeted novelty search.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
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.