CIGS Solar Cell Charge Transport Layer Patents: Leaders & Gaps 2026
- Filing has gone flat, not up. The peak year was 2018 at 4 families, and the 2022 midpoint sits at only 2 — this is a technology with a settled, not expanding, claim base.
- Cd-free buffer chemistry is the most-cited pocket. US20160336475A1's hexagonal-phase CdS-on-CIGS approach draws 21 citations, second only to a broader nanoparticle synthesis patent at 52.
- Filers cluster around a small set of university-industry pairs. Only 10 co-assignee pairs exist across 41 families, with the strongest links tying a Chinese solar manufacturer to a US university research group.
What this landscape covers
This landscape tracks patent families addressing the charge transport interface in CIGS (copper indium gallium selenide) thin-film solar cells: the buffer layer that sits between the p-type CIGS absorber and the n-type window layer, and the carrier-selective and interface-passivation schemes built around it. The search string isolates records that combine CIGS absorber terminology with buffer-specific language — CdS, Zn-O-S, carrier-selective layer, MoSe2 interface — under IPC classes for junction and heterojunction device structures. This is a narrow, structure-defined slice of the wider CIGS patent space, not the full thin-film photovoltaics literature.
41 published families sit inside this scope, spanning receiving offices led by the United States and China, with smaller volumes at the EPO, WIPO, and single filings in South Korea and Austria. Publication lags filing by roughly 18 months, so the most recent year on any chart understates real activity; treat the tail end of the trend as provisional.
Trend and technology composition
The filing curve and IPC spread both point to a technology area that reached its claim-density ceiling early and has not moved since.
A flat curve after an early peak
Filings ran from 0 in 2017 to a peak of 4 in 2018, then settled near the 2022 midpoint of 2 per year, with 2026 (partial) back at 0. There is no second wave visible in this data — the buffer-layer claim space for CIGS was staked out early and has not reopened.
Concentrated in semiconductor device claims, thin spread elsewhere
All 41 records classify under H01L (semiconductor devices), the core junction-structure class. Supporting activity is thin: C23C (coating & surface deposition) carries 5 records, H10P 4, and C01B, C04B, C25D three each, with B22F and B32B at 2 apiece. This tail of deposition- and materials-side classes signals that most inventive effort still centres on device architecture rather than novel deposition chemistry or laminate structure.
Shares are the percentage of the 41 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on CIGS Solar Cell Charge Transport Layer with Eureka
This page is one run against one query. Ask Eureka your own question about cigs solar cell charge transport layer and every answer comes back with the patent numbers behind it.
Try EurekaThe records shaping this space
Hexagonal phase epitaxial cadmium sulfide on copper indium gallium selenide for a photovoltaic junction
A method of manufacturing a photovoltaic structure includes forming a p-type semiconductor absorber layer containing a copper indium gallium selenide based material over a first electrode, forming an n-type cadmium sulfide layer over the p-type semiconductor absorber layer by sputtering in an ambient including hydrogen gas and oxygen gas, and forming a second electrode over the cadmium sulfide layer.Filed by Beijing Apollo Ding Rong Solar Technology Co., Ltd., published 2016-11-17. Second-most-cited record in the corpus at 21 citations.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | WO2009137637A2 | Nanoparticles and methods of making and using | 52 |
| 2 | US20160336475A1 | Hexagonal phase epitaxial cadmium sulfide on copper indium gallium selenide for a photovoltaic junction | 21 |
| 3 | US20120227811A1 | Electrochemical method of producing copper indium gallium diselenide (CIGS) solar cells | 18 |
| 4 | CN105355676A | 一种柔性CIGS薄膜太阳电池的背电极结构 | 12 |
| 5 | CN105470338A | 一种柔性叠层太阳电池及制备方法 | 10 |
| 6 | CN106784151A | 一种柔性铜铟镓硒薄膜太阳电池制备方法 | 6 |
| 7 | US20130206232A1 | Nanowires and methods of making and using | 6 |
| 8 | CN112259639A | 一种应用于玻璃衬底CIGS薄膜太阳电池的低成本制备方法 | 3 |
| 9 | KR1020200125097A | CIGS Method for compensation of pin-holes in CIGS photovoltaic absorber using In2S3-CdS hybrid buffer layer a… | 3 |
| 10 | US20190305156A1 | Photosensitive element and manufacturing method thereof, display panel and manufacturing method thereof | 3 |
Citation counts inside a searched corpus favour older records; read them as a signal of influence on later filings, not as 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 mean for a filing decision
Three patterns matter more than the headline family count when deciding where to file next.
The buffer layer claim base is settled, not growing
A flat-to-declining curve after a 2018 peak means the core device-architecture claims around CdS and Zn-O-S buffers are largely staked out. New filings here are more likely to be narrow process variants than foundational structure claims.
Device structure dominates over deposition chemistry
Every record in this scope touches semiconductor device classification; only a handful extend into coating, ceramics, or electroplating classes. That gap is where alternative deposition routes to the same junction structure remain lightly claimed.
Influence sits with a nanoparticle synthesis patent and a Cd-free-adjacent CdS method
The most-cited record in the corpus is a broader nanoparticle synthesis filing (52 citations), not a CIGS-specific one; the leading CIGS-specific record is the hexagonal-phase CdS sputtering method at 21. Both predate the flat filing period, consistent with older records accumulating more citations by exposure time alone.
Filing is largely solo, with a few dense university links
Co-assignment is rare in this dataset. Where it appears, it clusters around named individual inventors paired with university systems, and one Chinese solar manufacturer paired repeatedly with a US university council — suggesting sponsored or licensed academic research rather than broad industry consortia.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to cigs solar cell charge transport layer, with the prior art for and against each one.
Who is filing, and who has gone quiet
Momentum data shows every tracked assignee at zero filings in the most recent year — consistent with the flat overall trend, though publication lag means some of this understates 2025-2026 activity still working through the pipeline.
Beijing Apollo Ding Rong + University of Illinois
This pairing anchors the densest collaboration link in the dataset, tying a Chinese thin-film solar manufacturer to US academic research on CIGS junction structures — the same lineage behind the most-cited CIGS-specific patent in this corpus.
Korgel, Steinhagen and the University of Texas System
Brian Korgel appears paired both with Chet Steinhagen and with the University of Texas System Board of Regents, pointing to a university lab that filed jointly across several buffer-layer and nanoparticle-adjacent inventions rather than assigning solely to the institution.
Nitto Denko, CETC 18th Institute and others hold ground but aren't adding to it
Japanese, Chinese state-research and university assignees appear repeatedly in the ranking but show no filings in the most recent tracked year, matching the broader flat-to-declining trend rather than any single company pulling back.
| Assignee | Recent year | YoY |
|---|---|---|
| Nitto Denko Corporation | 0 | — |
| The 18th Research Institute of China Electronics Technology Group Corporation | 0 | — |
| University of Western Ontario | 0 | — |
| KORGEL BRIAN A | 0 | — |
| Shenzhen Institutes of Advanced Technology | 0 | — |
| Beijing Apollo Ding Rong Solar Technology Co., Ltd. | 0 | — |
| The Board of Trustees of the University of Illinois | 0 | — |
| Korea Institute of Science and Technology (KIST) | 0 | — |
Where to take this analysis
The family-level view here is a starting point for freedom-to-operate and whitespace screening, not a substitute for claim-by-claim review.
Run a claim-level check against US20160336475A1
Its sputtering-ambient method for hexagonal CdS on CIGS is the highest-cited CIGS-specific record in this scope; any process using hydrogen/oxygen ambient sputtering to form the buffer layer should be checked against its claim set directly.
Search this claim in EurekaScreen the Zn-O-S and MoSe2 branches separately
Both terms appear in the search scope but the IPC breakdown shows thin coverage outside core H01L device claims, suggesting the deposition and interface-chemistry side of these branches is less crowded than the device-structure side.
Explore white space in EurekaTrack the Beijing Apollo Ding Rong / University of Illinois lineage
This is the densest collaboration in the dataset and touches the second most-cited record; watch for follow-on filings or licensing activity from either party.
Monitor this assignee pair in EurekaCommon questions on CIGS buffer layer IP
In a CIGS device, the charge transport layer typically refers to the buffer layer between the p-type CIGS absorber and the n-type window layer, most often a thin CdS film, along with Cd-free alternatives such as Zn-O-S. It also covers carrier-selective layer designs and the CIGS/MoSe2 back-contact interface, since both are structured to manage electron and hole transport across a junction. Patents in this space claim the layer composition, its deposition method, or the resulting band alignment rather than the absorber itself.
The dataset shows a peak of 4 families in 2018 followed by a decline to around 2 per year by 2022, with no recovery through the most recent tracked years. This pattern is consistent with a claim space where the core device architectures were established early, leaving later filers to pursue narrower process variants rather than foundational structure claims. It also reflects broader industry attention shifting toward other thin-film and tandem architectures during this period, which reduces the pool of active CIGS-specific filers.
By citation count within this corpus, the most-cited record is a broader nanoparticle synthesis patent (52 citations) rather than a CIGS-specific structure claim; the leading CIGS-specific filing is US20160336475A1, assigned to Beijing Apollo Ding Rong Solar Technology, covering hexagonal-phase CdS grown on CIGS by sputtering, with 21 citations. Citation counts favour older records, so treat this as a measure of historical influence rather than current commercial dominance.
The IPC breakdown shows all 41 tracked families touching H01L semiconductor device classes, but only thin coverage in deposition- and materials-adjacent classes like C23C, C01B, C04B and C25D. That gap suggests alternative deposition routes to Zn-O-S graded buffers, MoSe2 interface passivation, and electroplated or ceramic-integrated buffer stacks are less crowded on the process side than on the device-structure side, making them worth a closer freedom-to-operate look before committing to a device-claim strategy.
CdS-based methods remain prominent in citation influence, led by US20160336475A1, but the overall filing count in this scope is small (41 families) and flat, so no single chemistry shows clear current dominance by filing volume. Zn-O-S and other Cd-free approaches appear in the search scope but carry thinner IPC coverage outside core device classes, which is more indicative of an open process-chemistry space than of CdS losing ground on claims already filed.
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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.