How to Make High-Efficiency Solar Cells with Stacked Layers
This patent describes a solar cell design that stacks two different types of light-absorbing layers, cadmium telluride and silicon, connecting them in parallel to capture more sunlight efficiently.
Original patent title: “Superstrate sub-cell voltage-matched multijunction solar cells”
This patent describes a solar cell design that stacks two different types of light-absorbing layers, cadmium telluride and silicon, connecting them in parallel to capture more sunlight efficiently. Granted to Alliance for Sustainable Energy in 2016 with 21 claims and 18 forward citations, and it is expected to expire in 2034.
Coverage
What does this patent actually cover?
This patent describes a special type of solar cell called a multijunction cell. It combines an "upper sub-cell" made of cadmium telluride (CdTe) with a "lower sub-cell," often made of silicon (Si), as stated in claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1 and claim 2. These two sub-cells are separated by a transparent insulating layer and are designed to be "voltage-matched," meaning they produce similar electrical pressure. Crucially, they are connected in parallel (claim 1), which allows their currents to add up while maintaining a consistent voltage. Light enters through a transparent "superstrate," like glass (claim 9), hitting the CdTe layer first, then passing through to the lower Si layer. For example, a solar panel could use this design to convert a broader spectrum of sunlight into electricity than a single-layer cell.
The gap
What does this patent NOT cover?
- Solar cells where the different light-absorbing layers are connected in series, rather than in parallel.
- Multijunction solar cells that do not use a cadmium telluride (CdTe) upper sub-cell.
- Designs where the upper and lower sub-cells are not specifically "voltage-matched."
- Solar cells that do not include a transparent insulating layer between the upper and lower sub-cells.
- Lower sub-cells that lack an interdigitated p-type and n-type back contact made of Si, as specified in claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation lies in combining two distinct solar cell materials (like CdTe and Si) into a stacked "multijunction" design where they are specifically "voltage-matched" and connected in parallel. This allows each layer to be optimized independently for different parts of the solar spectrum and then combined without the current mismatch problems often seen in serially connected stacked cells.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
High-efficiency research solar cells
Next-generation thin-film solar panels
Concentrator photovoltaics (CPV)
Space-based solar arrays
Why it matters
The bigger picture
Solar cells that can capture more of the sun's energy are crucial for making solar power more affordable and widespread. This patent offers a way to combine different materials, like CdTe and Si, each good at absorbing different parts of the light spectrum, into a single, more efficient device. This approach helps overcome limitations of single-material solar cells and could lead to higher power output from solar panels.
Filed
April 2, 2014
Granted
March 15, 2016
Market context
Who's building on this
Companies in this space
The Alliance for Sustainable Energy LLC operates the National Renewable Energy Laboratory (NREL), which is a leading research institution in renewable energy technologies. NREL continues to conduct extensive research in advanced photovoltaics, including multijunction solar cells and thin-film technologies, and often collaborates with industry partners to bring these innovations to market. Other major solar research groups and companies focused on high-efficiency photovoltaics would also be exploring similar concepts.
Market impact
This patent contributes to the ongoing effort to increase solar cell efficiency, particularly for thin-film technologies like CdTe. By enabling a more efficient combination of different semiconductor materials, it could lead to the development of solar panels with higher power output per square meter. This could make solar energy more competitive by reducing the overall cost of electricity generated, influencing future designs for high-performance solar modules.
Claim 1 — Plain English
What this patent covers
This patent describes a special type of solar cell called a multijunction cell. It combines an "upper sub-cell" made of cadmium telluride (CdTe) with a "lower sub-cell," often made of silicon (Si), as stated in claim 1 and claim 2. These two sub-cells are separated by a transparent insulating layer and are designed to be "voltage-matched," meaning they produce similar electrical pressure. Crucially, they are connected in parallel (claim 1), which allows their currents to add up while maintaining a consistent voltage. Light enters through a transparent "superstrate," like glass (claim 9), hitting the CdTe layer first, then passing through to the lower Si layer. For example, a solar panel could use this design to convert a broader spectrum of sunlight into electricity than a single-layer cell.
The clever bit
The innovation lies in combining two distinct solar cell materials (like CdTe and Si) into a stacked "multijunction" design where they are specifically "voltage-matched" and connected in parallel. This allows each layer to be optimized independently for different parts of the solar spectrum and then combined without the current mismatch problems often seen in serially connected stacked cells.
What it does not cover
- Solar cells where the different light-absorbing layers are connected in series, rather than in parallel.
- Multijunction solar cells that do not use a cadmium telluride (CdTe) upper sub-cell.
- Designs where the upper and lower sub-cells are not specifically "voltage-matched."
- Solar cells that do not include a transparent insulating layer between the upper and lower sub-cells.
- Lower sub-cells that lack an interdigitated p-type and n-type back contact made of Si, as specified in claim 1.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Moderate
Citation count
26/40
Moderately cited
Claim breadth
14/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$205K – $655K
Midpoint $410K · 7.6 yr remaining · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
21 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Mascarenhas, A., & Alberi, K. (2016). How to Make High-Efficiency Solar Cells with Stacked Layers (U.S. Patent No. 9,287,431). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/9287431/superstrate-sub-cell-voltage-matched-multijunction-solar-cells
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Make High-Efficiency Solar Cells with Stacked Layers cover?
This patent describes a solar cell design that stacks two different types of light-absorbing layers, cadmium telluride and silicon, connecting them in parallel to capture more sunlight efficiently.
Who owns patent US 9287431?
Alliance for Sustainable Energy owns this patent, granted in 2016.
When does this patent expire?
This patent is expected to expire on April 2, 2034, when the invention enters the public domain.
What is patent US 9287431 cited by?
This patent has been cited by 18 later patents that build on its ideas.
What problem does this patent solve?
Solar cells that can capture more of the sun's energy are crucial for making solar power more affordable and widespread. This patent offers a way to combine different materials, like CdTe and Si, each good at absorbing different parts of the light spectrum, into a single, more efficient device. This approach helps overcome limitations of single-material solar cells and could lead to higher power output from solar panels.
What does this patent NOT cover?
Solar cells where the different light-absorbing layers are connected in series, rather than in parallel.
Patent monitoring