Bifacial and TOPCon Cell Patents: Who Leads, Where the Gaps Are 2026
- Filing already peaked. 2023 was the high point at 31 families; the 2022 midpoint of 21 shows growth flattening rather than accelerating into 2026.
- China dominates the filing venue. 61 of 119 families were filed through the China receiving office, more than four times the next-largest venue.
- The oldest cited art still anchors the field. US filings on bifacial back-surface doping and reflectors from 2010 remain among the most-cited records, ahead of newer TOPCon-specific disclosures.
Filing growth compares 2021 (12 records) with 2024 (23) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 119 records in scope (CR5), not by the ranked leaders only.
A semiconductor-device field built on two overlapping architectures
Bifacial cell design and TOPCon (tunnel oxide passivated contact) construction are technically distinct but claim-overlapping: both compete for coverage on rear passivation, dopant profiles and the thin dielectric layers that determine bifaciality factor and efficiency gain. Nearly every record in this dataset sits inside H01L, the core semiconductor-device classification, with a much smaller secondary cluster in cabling, glass/enamel coatings and crystal growth — evidence that the contest is happening inside the cell stack itself, not in peripheral materials.
Search-office data show China as the primary filing venue by a wide margin, with Europe, the US and the PCT route drawing roughly comparable secondary volumes. That distribution matches where bifacial and TOPCon manufacturing capacity is concentrated, and it means freedom-to-operate analysis for this architecture family has to start with Chinese-language prior art, not end with it.
Filing trend and technology composition
Publication data through the 2026-07-31 cut-off shows a field that grew steadily through the early 2020s and has since leveled off, concentrated almost entirely in one IPC subclass.
A 2023 peak followed by a plateau
Filings rose from a single 2017 record to a peak of 31 in 2023. With the 2022 midpoint at 21, the growth curve is flattening rather than climbing — and because publication typically lags filing by around 18 months, the apparent 2025-2026 falloff should be read as a reporting gap, not a real drop in R&D activity.
Concentrated in one core classification
All 119 records classify under H01L (semiconductor devices), with a secondary cluster of 19 in H10P. Everything else — cabling and insulators, glass and enamel coatings, general cleaning processes, surface coating and crystal growth — accounts for single-digit counts each, confirming that the competitive claim space is the cell stack itself rather than adjacent materials or process equipment.
Shares are the percentage of the 119 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Bifacial and TOPCon Cell Architectures with Eureka
This page is one run against one query. Ask Eureka your own question about bifacial and topcon cell architectures and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited prior art still traces back to bifacial fundamentals
TOPCON CELL, METHOD FOR MANUFACTURING THE SAME, AND ELECTRICAL DEVICE
A method for manufacturing a TOPCon cell includes following steps: texturing a front side of an silicon wafer and then preparing a PN junction; forming a tunnel oxide layer, an intrinsic polysilicon layer, a doped polysilicon layer, and a silicon oxide mask layer in sequence on a back side of the silicon wafer, wherein the tunnel oxide layer is deposited by PEALD at a deposition temperature of 150°C to 200°C, the doped polysilicon layer is deposited by PECVD, and the silicon oxide mask layer has a thickness of 10 nm to 40 nm; removing a wraparound silicon oxide mask layer material and a wraparound polysilicon layer material from the front side of the silicon wafer, and then removing the…Abstract excerpted from the published filing; process parameters (deposition temperature, mask thickness) are the specific limitations most likely to matter in a design-around analysis.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | CN109980022A | 一种P型隧穿氧化物钝化接触太阳能电池及其制备方法 | 39 |
| 2 | CN110473926A | 一种钝化接触太阳能电池及其制备方法 | 38 |
| 3 | US20100275995A1 | Bifacial solar cells with back surface reflector | 31 |
| 4 | US20100275984A1 | Bifacial solar cells with back surface doping | 28 |
| 5 | CN115148857A | 一种TOPCon电池及其制作方法 | 19 |
| 6 | CN116741871A | 一种扩硼SE结构的N型TOPCon电池制作方法 | 16 |
| 7 | CN115602355A | 导电浆料及其制备的太阳能电池 | 15 |
| 8 | US20220115545A1 | Tunnel oxide passivated contact solar cell | 13 |
| 9 | CN117476796A | 一种TOPCon电池及TOPCon电池的制备方法 | 12 |
| 10 | WO2010126572A2 | Bifacial solar cells with back surface reflector | 11 |
Citation counts favor older documents inside any searched corpus; treat this as a map of influence on subsequent filings, not a ranking of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers say about where this field stands
Three patterns stand out once the filing trend, classification spread and citation data are read together.
Growth has plateaued, not accelerated
The climb from 1 filing in 2017 to a 2023 peak of 31 looks steep in isolation, but the 2022 midpoint of 21 shows the curve was already flattening before the peak. Combined with the 18-month publication lag, the field reads as maturing into a stable filing rate rather than entering a new growth phase.
Nearly all activity sits in one subclass
Every record in the dataset classifies under H01L, with a secondary H10P cluster of 19. The remaining subclasses — cabling, glass coatings, cleaning, surface deposition, crystal growth — each register in single digits, meaning claim pressure is overwhelmingly on the semiconductor device structure itself.
Older bifacial fundamentals still outrank newer TOPCon filings
The two most-cited US records date to 2010 and address bifacial back-surface reflectors and doping — general architecture, not TOPCon-specific chemistry. Newer Chinese filings on passivated-contact cells and TOPCon manufacturing are catching up in citation count but have not yet overtaken the foundational bifacial disclosures.
China is the dominant filing venue by a wide margin
China accounts for roughly half of all records, more than four times the next venue. Europe, the US and the PCT route each draw comparable secondary volumes, and Australia and Taiwan trail further behind — a distribution that should shape where freedom-to-operate searches start.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to bifacial and topcon cell architectures, with the prior art for and against each one.
A field with a few repeat filers and a long tail
Co-assignee pairings are limited and concentrated: only 10 co-assignee pairs appear across the dataset, and the strongest pairing links two related entities within the same corporate group rather than an external partnership.
英利能源发展 group entities file together
Yingli Energy Development Co., Ltd. and its 保定 affiliate form the strongest co-assignee pairing in the dataset at 9 shared records, consistent with a single corporate group splitting filings across related legal entities rather than a cross-company collaboration.
Solarcell Materials Co., Ltd. pairs with named inventors
This materials-focused assignee appears in two of the dataset's strongest co-assignee pairs, both linked to individually named inventors rather than corporate co-assignees — a pattern typical of smaller specialist filers protecting inventor-attributed process work.
通威太阳能(眉山) anchors the TOPCon manufacturing claims
The representative record in this dataset — a TOPCon manufacturing method with specific PEALD deposition temperature and mask thickness limitations — is assigned to this manufacturer, indicating active process-patenting even as its most recent filing year shows no new records.
| Assignee | Recent year | YoY |
|---|---|---|
| Tongwei Solar (Meishan) Co., Ltd. | 0 | — |
| Solarcell Materials Co., Ltd. | 0 | — |
| Yingli Energy Development Co., Ltd. | 0 | -100% |
| Yingli Energy Development (Baoding) Co., Ltd. | 0 | — |
| OUNADJELA KAMEL | 0 | — |
| KRAENZL ANDREAS | 0 | — |
| KIRSCHT FRITZ G | 0 | — |
| KAES MARTIN | 0 | — |
Where to take this analysis
The filing and citation data point to specific next steps depending on whether you are clearing freedom-to-operate or scoping new claims.
Run a China-first freedom-to-operate check
With 61 of 119 families filed through the China receiving office, any clearance search that starts in English-language databases alone will miss the majority of relevant prior art in this space.
Explore in Patsnap Eureka →Screen the under-claimed branches before drafting
Low record counts in crystal growth, coating processes and conductor integration suggest these adjacent branches have not been heavily claimed relative to the core cell-structure cluster.
Explore in Patsnap Eureka →Track whether 2023's peak was a plateau or a ceiling
Because publication lags filing by roughly 18 months, the 2025-2026 data is not yet reliable evidence of a slowdown; revisit the trend once later filings publish.
Explore in Patsnap Eureka →Common questions about bifacial and TOPCon cell patents
Bifacial cell patents cover architectures designed to capture light from both the front and rear surfaces of the cell, typically claiming back-surface doping profiles or reflector structures. TOPCon (tunnel oxide passivated contact) patents cover a specific rear-passivation technique using a thin tunnel oxide layer plus a doped polysilicon layer to reduce recombination losses. In practice the two overlap heavily in this dataset, because a bifacial cell can use a TOPCon rear-contact structure, and most records here classify under the same core semiconductor-device IPC subclass rather than sitting in separate technical silos.
The dataset shows a small group of repeat filers alongside a longer tail of single-filing entrants, with the strongest co-assignee links occurring within single corporate groups splitting filings across related legal entities rather than across competing companies. Filing venue data shows China as the dominant jurisdiction, accounting for roughly half of all records, which should guide any competitor-mapping exercise toward Chinese-language filings first. None of the tracked assignees in the recent-year momentum data show growth in the latest year, consistent with the broader plateau in filing activity since the 2023 peak.
The raw trend shows filings peaking at 31 in 2023 and declining afterward, but that decline should not be read at face value. Patent publication typically lags actual filing by around 18 months, so 2025 and 2026 figures are structurally incomplete and will rise as pending applications publish. The more reliable read is that growth had already flattened by the 2022 midpoint of 21 filings, suggesting the field is settling into a steady filing rate rather than accelerating or collapsing.
The clearest white space sits outside the dominant H01L semiconductor-device classification, in adjacent branches with only single-digit record counts: crystal growth methods for tunnel-oxide substrates, glass and enamel rear-passivation coatings, cleaning processes for removing wraparound deposited layers, and conductor/insulator integration for bifacial modules. These branches support the core cell architecture but have not attracted the same claim density, making them worth screening before assuming the entire field is saturated. A first claim in one of these areas would likely need to tie a specific material or process step to a measurable efficiency or bifaciality outcome to distinguish it from the dense core prior art.
The most-cited records in this dataset include two US filings from 2010 on bifacial back-surface reflectors and doping, both with citation counts in the high 20s to low 30s, alongside newer Chinese filings on passivated-contact and TOPCon cell manufacturing with citation counts approaching 40. This mix shows that foundational bifacial architecture patents still anchor the citation network even as TOPCon-specific process patents catch up. Because citation counts favor older documents in any searched corpus, high citation numbers should be read as a signal of historical influence rather than current commercial dominance.
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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.