The World's #1 Renewable Energy Network for News, Information, and Companies.
Untitled Document

All-carbon Solar Cell Harnesses Infrared Light

About 40 percent of the solar energy reaching Earth's surface lies in the near-infrared region of the spectrum — energy that conventional silicon-based solar cells are unable to harness. But a new kind of all-carbon solar cell developed by MIT researchers could tap into that unused energy, opening up the possibility of combination solar cells — incorporating both traditional silicon-based cells and the new all-carbon cells — that could make use of almost the entire range of sunlight's energy.

“It’s a fundamentally new kind of photovoltaic cell,” says Michael Strano, the Charles and Hilda Roddey Professor of Chemical Engineering at MIT and senior author of a paper describing the new device that was published this week in the journal Advanced Materials.

The new cell is made of two exotic forms of carbon: carbon nanotubes and C60, otherwise known as buckyballs. “This is the first all-carbon photovoltaic cell,” Strano says — a feat made possible by new developments in the large-scale production of purified carbon nanotubes. “It has only been within the last few years or so that it has been possible to hand someone a vial of just one type of carbon nanotube,” he says. In order for the new solar cells to work, the nanotubes have to be very pure, and of a uniform type: single-walled, and all of just one of nanotubes’ two possible symmetrical configurations.

Other groups have made photovoltaic (PV) cells using carbon nanotubes, but only by using a layer of polymer to hold the nanotubes in position and collect the electrons knocked loose when they absorb sunlight. But that combination adds extra steps to the production process, and requires extra coatings to prevent degradation with exposure to air. The new all-carbon PV cell appears to be stable in air, Strano says.

The carbon-based cell is most effective at capturing sunlight in the near-infrared region. Because the material is transparent to visible light, such cells could be overlaid on conventional solar cells, creating a tandem device that could harness most of the energy of sunlight. The carbon cells will need refining, Strano and his colleagues say: So far, the early proof-of-concept devices have an energy-conversion efficiency of only about 0.1 percent.

But while the system requires further research and fine-tuning, “we are very much on the path to making very high efficiency near-infrared solar cells,” says Rishabh Jain, a graduate student who was lead author of the paper.

Because the new system uses layers of nanoscale materials, producing the cells would require relatively small amounts of highly purified carbon, and the resulting cells would be very lightweight, the team says. “One of the really nice things about carbon nanotubes is that their light absorption is very high, so you don’t need a lot of material to absorb a lot of light,” Jain says.

Typically, when a new solar-cell material is studied, there are large inefficiencies, which researchers gradually find ways to reduce. In this case, postdoc and co-author Kevin Tvrdy says, some of these sources of inefficiency have already been identified and addressed: For instance, scientists already know that heterogeneous mixtures of carbon nanotubes are much less efficient than homogeneous formulations, and material that contains a mix of single-walled and multiwalled nanotubes are so much less efficient that sometimes they don’t work at all, he says.

“It’s pretty clear to us the kinds of things that need to happen to increase the efficiency,” Jain says. One area the MIT researchers are now exploring is more precise control over the exact shape and thickness of the layers of material they produce, he says.

The team hopes that other researchers will join the search for ways to improve their system, Jain says. “It’s very much a model system,” he says, “and other groups will help to increase the efficiency.”

But Strano points out that since the near-infrared part of the solar spectrum is currently entirely unused by typical solar cells, even a low-efficiency cell that works in that region could be worthwhile as long as its cost is low. “If you could harness even a portion of the near-infrared spectrum, it adds value,” he says.

Strano adds that one of the paper’s anonymous peer reviewers commented that the achievement of an infrared-absorbing carbon-based photovoltaic cell without polymer layers is the realization of “a dream for the field.”

The work also involved MIT graduate students Rachel Howden, Steven Shimizu and Andrew Hilmer; postdoc Thomas McNicholas; and professor of chemical engineering Karen Gleason. It was supported by the Italian company Eni through the MIT Energy Initiative, as well as the National Science Foundation and the Department of Defense through graduate fellowships to Jain and Howden, respectively.

Untitled Document

Get All the Renewable Energy World News Delivered to Your Inbox - FREE!

Subscribe to Renewable Energy World Magazine and our award-winning e-Newsletter to stay up to date on current news and industry trends.

 Subscribe Now



A Case Study in Energy-Transition Momentum

Tim King South Australia is clearly at the forefront of the global energy transition as it establishes a fast-moving model oth...

Listen Up: Can I Get Solar if my Roof is Shaded?

The Energy Show on Renewable Energy World Rooftop solar panels only work when they are in direct sunlight. So if you have a partially shaded roof, the output o...

US Senate Democrats Unveil Energy Bill That Restores PTC and Extends ITC

Brian Eckhouse, Bloomberg Senate Democrats unveiled a bill that would provide more tax credits for renewable energy while killing some tax ince...

US, China Solar PV Players Team Up, Invest $100M in Chile, Uruguay and Japan

Andrew Burger Private equity infrastructure specialist Hudson Clean Energy Partners and Hong Kong-based independent power producer ...


Fronius Shifting the Limits in Solar-Plus: It’s not just about products, it’s about solutions.

Fronius USA, who just recently launched the all-new Fronius SnapINverter line this past...

IREC Announces Changes in Regulatory Team

The Interstate Renewable Energy Council (IREC), a not-for-profit organization which for...

IREC Awarded New Funding to Advance Digital Credentials

The Interstate Renewable Energy Council (IREC) proudly announces funding for an innovat...

$100 Discount on 5-day Advanced PV Project Experience Workhop

Upcoming 5-day Workshops: Nov. 7 - 11 Feb. 6 - 10


NY Gov. Cuomo Pledges to Create Carbon Market use Solar, Wind to reduce Climate Change

This week former Vice President Al Gore joined with New York Gov. Andrew Cuomo (D) to sign the Under 2 MOU, a directi...
clean energy

In Clean Energy, The Truth Matters

A group of about 20 protesters gathered outside the Sheraton in Burlington, Vt., early on Oct. 8 as attendees arrived...

Industry Focus: Cleantech: 1366 Technologies joins Solarcity in New York

1366 is set to build a factory just up the road (OK, it is a long road – NYS Thruway) from Solarcity.  The...



Volume 18, Issue 4


To register for our free
e-Newsletters, subscribe today:


Tweet the Editors! @jennrunyon



Successfully Integrating Solar: A Proactive Approach

•      What does the increasing solar penetrati...

Canadian Solar Inverters Webinar

Canadian Solar is proud to be hosting two free webinars in October! The ...

JuiceBox Energy Certified Installer Class

JuiceBox Energy is rapidly building out its national certified installer...


SPI Brings Out The Best In Solar

Phew…...those cross-country flights sure take a lot out of a guy....

Connecting The Dots

One of the most important attributes of a true sales professional is the...

7 Pitfalls Of Simple Payback Period

There are many pitfalls of using Simple Payback Period (SPP) as a measur...


Renewable Energy: Subscribe Now

Solar Energy: Subscribe Now

Wind Energy: Subscribe Now

Geothermal Energy: Subscribe Now

Bioenergy: Subscribe Now