Researchers Create Multi-Junction Solar Cells from Off-the-Shelf Components
June 26, 2019 | NC State UniversityEstimated reading time: 2 minutes
Multi-junction solar cells are both the most efficient type of solar cell on the market today and the most expensive type of solar cell to produce. In a proof-of-concept paper, researchers from North Carolina State University detail a new approach for creating multi-junction solar cells using off-the-shelf components, resulting in lower cost, high-efficiency solar cells for use in multiple applications.
Multi-junction, or stacked, solar cells are currently the most efficient cells on the market, converting up to 45% of the solar energy they absorb into electricity. The cells are constructed by stacking semiconductors with varying bandgaps on top of one another, thereby allowing the cell to absorb differing wavelengths of solar radiation. However, these cells are much more expensive to produce than less efficient thin solar films.
“We want to create high efficiency solar cells at a reasonable cost,” says Salah Bedair, Distinguished Professor of Electrical and Computer Engineering at NC State and lead author of the research. “Silicon-based thin solar cells are very popular because the material has around 20% efficiency and the cells cost about 1/10th what a multi-junction solar cell costs. And other low cost, lower efficiency materials are gaining popularity as well. If we could create stacked solar cells using this existing technology we would be well on our way to reaching our goal.”
However, you cannot merely stack different solar cells on top of each other—the different materials are structurally incompatible, and so charges cannot pass through them to be collected. To solve that problem in current multi-junction solar cells heavily doped metals are used to create a tunnel junction between the various layers—adding significant expense and complexity to the multi-junction solar cell’s creation.
Bedair and his team developed a simpler approach, utilizing intermetallic bonding to bond solar cells made of different materials. In a proof-of-concept, the team stacked an off-the-shelf gallium arsenide solar cell on top of a silicon solar cell.
“In multi-junction solar cells the tunnel junction enables electric connectivity by acting as a metal-to-metal connection,” Bedair says. “In our system, indium serves as a shortcut to that. The existing metal contacts of the individual cells are covered with indium films. The indium films bond to themselves easily at room temperature under low pressure. The result is a solar cell made of two different materials that is mechanically stacked and electrically connected.
“With this technique we are able to take advantage of inexpensive, off-the-shelf solutions without having to develop all new technology. Manufacturers could simply tweak their existing products slightly to increase their efficiency in multi-junction solar cells, rather than having to create new products.”
The paper, “A New Approach for Multi-Junction Solar Cells from Off-the-Shelf Individual Cells: GaAs/Si” was presented at the IEEE Photostatic Specialist Meeting held June 19 in Chicago, IL. NC State graduate student Brandon Hagar and research assistant professor Peter Colter are co-authors of the paper. The work was supported by the National Science Foundation under grant 1665211.
A patent application has been submitted for the work. The authors are interested in collaborating with potential academic and industry partners.
Suggested Items
LQDX Divests Aluminum Soldering Business - Mina™ - to Taiyo America Inc.
05/02/2024 | PRNewswireLQDX, formerly known as Averatek Corp., developer of high-performance materials for advanced semiconductor manufacturing, today announced that it has divested its aluminum soldering business – known as MinaTM – to Taiyo America Inc., a global market leader in advanced electronic materials.
Indium Corporation Expert to Present on Pb-Free Solder for Die-Attach in Discrete Power Applications
04/30/2024 | Indium CorporationIndium Corporation Product Manager – Semiconductor Dean Payne will present at the Advanced Packaging for Power Electronics conference, hosted by IMAPS, held May 8-9 in Woburn, Massachusetts, USA.
Real Time with... IPC APEX EXPO 2024: Adhesive Materials and Equipment Update with Dymax
05/01/2024 | Real Time with...IPC APEX EXPOVirginia Hogan, global business development manager at Dymax, discusses adhesive materials, dispensing and curing equipment, a new, high-reliability conformal coating, and various materials and dispensing methods.
Real Time with... IPC APEX EXPO 2024: Sustainability in the Industry
04/26/2024 | Real Time with...IPC APEX EXPOGuest Editor Henry Crandall and Chris Nash of Indium Corporation discuss the company's 90th anniversary and its focus on sustainability. They focus on the benefits of sustainable materials, their compatibility, and value propositions. The conversation also highlights how Durafuse LT technology's role in reducing reflow temperatures is leading to significant cost and energy savings. Nash also touches on downstream sustainability efforts such as using recycled materials for packaging.
SMC Korea 2024 to Highlight Semiconductor Materials Trends and Innovations on Industry’s Path to $1 Trillion
04/24/2024 | SEMIWith Korea a major consumer of semiconductor materials and advanced materials a key driver of innovation on the industry’s path to $1 trillion, industry leaders and experts will gather at SMC (Strategic Materials Conference) Korea 2024 on May 29 at the Suwon Convention Center in Gyeonggi-do, South Korea to provide insights into the latest materials developments and trends. Registration is open.