CdTe Thin-Film Solar Cell Patents: Who Leads, Where Gaps Are 2026
- Filings peaked in 2018 at 27 families and have not returned to that level since, including a 2022 midpoint of just 5 — this is a plateaued field, not a growing one.
- H01L device claims outnumber coating-process claims six to one 351 records sit in core semiconductor device claims against 55 in C23C coating and deposition, showing where the claim density actually is.
- Only 10 co-assignee pairs exist across 388 families with one pairing, China Triumph International Engineering and its co-filer, accounting for 46 shared filings — collaborative filing is rare and concentrated.
A plateaued field built on a small set of foundational device stacks
CdTe thin-film solar cell charge transport layer patents cover the structures that move and separate charge carriers inside a cadmium telluride device: CdS buffer layers, back-contact formation, and the window-layer interfaces that sit between them. Across the 388 patent families published between 2015 and mid-2026, filing activity is heavily weighted toward full device-level claims rather than standalone process or coating claims, and the field’s busiest year, 2018, has not been matched since.
Publication lag of roughly 18 months means recent-year filing counts, including the most recent year in this dataset, understate real activity — but the multi-year decline visible well before that lag window is a separate and more durable signal that the core architecture in this space is largely settled.
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Filing trends and technology composition
388 patent families published between 2015 and mid-2026 map a field that peaked in 2018 and has not recovered that level of activity since.
Filings by year
Filings rose to a peak of 27 in 2018, fell back toward single digits by the 2022 midpoint, and sit at low levels through the most recent, still-incomplete filing year — publication lag of roughly 18 months means the last one to two years understate true filing activity.
Technology composition by IPC subclass
Device-level claims under H01L dominate at 351 records, more than six times the next largest subclass, C23C coating and surface deposition at 55; smaller pockets in electroplating, coating apparatus and coating processes point to narrower, less-contested process claims around the core device architecture.
Shares are the percentage of the 388 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on CdTe Thin-Film Solar Cell Charge Transport Layer with Eureka
This page is one run against one query. Ask Eureka your own question about cdte thin-film solar cell charge transport layer and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Cadmium telluride solar cell and preparation method thereof (US20230317870A1)
A cadmium telluride solar cell and a preparation method thereof. The method includes providing a substrate, and forming a window layer on a first surface of the substrate, the window layer is made of magnesium-doped zinc oxide; forming a light absorbing layer on a surface of the window layer, the light absorbing layer includes a composite layer of cadmium selenide, selenium-doped cadmium telluride, and cadmium telluride; and forming a back electrode layer on a surface of the light absorbing layer. The use of the composite structure of cadmium selenide, selenium-doped cadmium telluride, and cadmium telluride allows the solar cell to absorb long-wavelength and short-wavelength light to the max.Filed by China Triumph International Engineering, published 2023-10-05.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6137048A | Process for fabricating polycrystalline semiconductor thin-film solar cells, and cells produced thereby | 241 |
| 2 | US6169246B1 | Photovoltaic devices comprising zinc stannate buffer layer and method for making | 161 |
| 3 | US6548751B2 | Thin film flexible solar cell | 153 |
| 4 | US20030041894A1 | Thin film flexible solar cell | 106 |
| 5 | US20090242029A1 | Junctions in substrate solar cells | 95 |
| 6 | US20030011047A1 | Photovoltaic device | 83 |
| 7 | US7829785B2 | Thin film solar cell with finger pattern | 70 |
| 8 | US7825329B2 | Thin film solar cell manufacturing and integration | 69 |
| 9 | US20050224111A1 | Photovoltaic device | 57 |
| 10 | US20110249219A1 | Integrated display and photovoltaic element | 52 |
Ranked by citation count within the searched corpus; older records accumulate more citations by nature of time in circulation, so treat this as a measure of influence on later claim drafting rather than current commercial relevance.
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Browse MCP servers →What the filing pattern signals
Three data points matter most for anyone deciding where to file next or who to watch: where filing volume sits by technology area, how concentrated collaborative activity is, and how citation influence tracks age rather than current relevance.
Device claims dominate over process claims
Semiconductor device claims under H01L account for the large majority of records, more than six times the next largest subclass. Coating and deposition process claims (C23C) and photovoltaic device claims (H10F) make up smaller, more specialised pockets.
Joint filing is rare and highly concentrated
Only 10 co-assignee pairs exist across the entire dataset. The strongest pairing, between China Triumph International Engineering and its affiliated co-filer, dwarfs every other pair by a wide margin, indicating most other filers work independently.
Activity has cooled well off its 2018 peak
Filings rose to 27 in 2018, fell to 5 by the 2022 midpoint, and sit near their lowest point in the most recent, still-partial year. Recent-year momentum for the largest historical assignees has dropped to zero, suggesting consolidation or a pivot to other cell chemistries.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to cdte thin-film solar cell charge transport layer, with the prior art for and against each one.
Who is filing, and where the gaps sit
Filing in this space is concentrated among a handful of assignees with sustained programs, most of them tied to established CdTe module manufacturers, alongside a long tail of single-filing entrants. Recent-year momentum has dropped to zero across the largest historical filers, which is worth reading alongside the overall plateau in filing volume.
China Triumph International Engineering and affiliated co-filer
This pairing accounts for the strongest co-assignee relationship recorded in the dataset, far ahead of any other pair, and underlies the representative 2023 graded-absorber filing.
Largest historical filers show no recent activity
Six of the assignees with the most historical filings, including First Solar and General Electric, recorded zero filings in the most recent year tracked, consistent with the broader multi-year decline in filing volume.
Joint filing is the exception, not the norm
With only 10 co-assignee pairs identified across the entire dataset, the large majority of families are filed by a single assignee, suggesting limited cross-licensing or joint-venture activity in this specific claim area.
| Assignee | Recent year | YoY |
|---|---|---|
| China Triumph International Engineering Co., Ltd. | 0 | — |
| CTF Solar Co., Ltd. | 0 | — |
| First Solar, Inc. | 0 | — |
| General Electric Company | 0 | — |
| Solar Systems and Equipment Co., Ltd. | 0 | — |
| Ulel Solar Co., Ltd. | 0 | — |
| Reel Solar, Inc. | 0 | — |
| WANG JIAXIONG | 0 | — |
Where to take this analysis
The filing data points to a settled core architecture with narrow openings in adjacent process claims. The next steps depend on whether the goal is freedom-to-operate, sourcing new filing angles, or tracking a specific competitor.
Run a freedom-to-operate check on the graded-absorber approach
If working with selenium-doped CdTe absorber compositions, check current legal status on the China Triumph International Engineering family and related filings before finalising a device stack.
Check claim scope in EurekaExplore the back-contact electroplating white space
Thinner filing density in electrodeposition-based back-contact formation suggests room for a narrowly scoped process claim distinct from the crowded device-stack space.
Explore this branch in EurekaTrack assignee momentum going forward
With the largest historical filers showing zero recent-year activity, watching for new entrants or a shift toward different cell chemistries is more informative than tracking the incumbents.
Set up monitoring in EurekaCommon questions about CdTe thin-film charge transport patents
Filing activity in this dataset clusters around a small number of assignees with sustained multi-year programs, alongside a long tail of single-filing entrants. China Triumph International Engineering and its affiliated co-filer show the strongest joint filing pattern recorded, appearing together in far more filings than any other pair in the dataset. That said, recent-year momentum for the largest historical filers has slowed to zero in the most current year tracked, which is consistent with the broader plateau in filings since the 2018 peak.
A CdS buffer layer sits between the CdTe absorber and the front window layer in a cadmium telluride thin-film solar cell, and it is central to forming the p-n junction that separates charge carriers. It appears throughout this search string because it is one of the defining structural elements distinguishing CdTe cell claims from other thin-film chemistries. Many of the most-cited records in this dataset, including work on zinc stannate buffer layers, are direct variations on this junction design filed to improve transmission or reduce absorption losses in the buffer itself.
Filing volume peaked at 27 families in 2018 and has trended down since, with the 2022 midpoint at only 5 and no strong recovery through the most recent years tracked. This does not necessarily mean the underlying technology has stalled commercially, since publication lag of about 18 months means the last one to two years in any patent trend understate real activity. But the multi-year plateau visible even before that lag window suggests the core device architecture is well-established and new filings are increasingly incremental rather than foundational.
The dataset shows heavy concentration in core semiconductor device claims under H01L, with much thinner coverage in adjacent process areas like electroplating-based back-contact formation and coating-apparatus claims. These thinner subclasses have far fewer filers and almost no dense co-assignee clustering, which is a reasonable proxy for where claim space remains genuinely open. A first filing targeting a specific process parameter window in back-contact electrodeposition, rather than another variation on the absorber-buffer device stack, is more likely to clear a clean prior art search.
The most-cited records, including the polycrystalline thin-film fabrication patent with 241 citations and the zinc stannate buffer layer patent with 161, date back far enough that their core terms are likely expired or close to expiry. High citation counts in a search corpus like this one reflect historical influence on how later claims were drafted, not necessarily live enforceability today. Anyone assessing freedom to operate should still check current legal status directly, since citation volume alone is not evidence a patent remains in force.
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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.