Tara P. Dhakal, an assistant professor of electrical and computer engineering, was awarded a five-year, $500,000 NSF CAREER grant for his study “Toward Twenty Year Lifetime: Hermetic Sealing for Perovskite Solar Cells.” The proposal was one of just 11 to be funded in a field of 150 proposals.

“Most solar cells are made from silicon and, while those solar cells are highly efficient, they have their limitations,” says Dhakal, who also serves as interim director of Binghamton’s Center for Autonomous Solar Power.

His work focuses on solar cells made with perovskite, a crystalline mineral found in nature that has shown the potential to create solar cells that are just as efficient as the silicon-based type.

“Unfortunately, the current versions of perovskite solar cells are typically fabricated with toxic lead,” Dhakal says. He wants to replace lead with non-toxic germanium.

“Germanium and lead both come from column 14 on the periodic table,” Dhakal says. “Other researchers have tried, without success, to use tin for the same reason but I’ve found evidence that germanium has a better chance of success.”

If he is able to replace the lead in the perovskite solar cells, they could prove to be more environmentally friendly than other solar cells.

However, even with the lead removed, there is another issue that could prevent perovskite solar cells from being deployed for an extended period of time.

That’s why Dhakal’s study will also be looking at ways to make perovskite solar cells last longer.

“Lead perovskite solar cells have only lasted for several months under ideal laboratory conditions,” he says. “With my proposed sealing techniques, I predict that module lifetimes could be greater than 20 years.”

With Dhakal’s seal on the perovskite solar cells, they could have the same shelf life that silicon solar cells do. Without lead and with this sealing, the cells will become more practical for use — which Dhakal says will facilitate a wider reach for solar power.

“Silicon makes a robust solar cell but one thing it misses is flexibility,” he says. “The perovskite solar cells could be made on fabrics or plastics, which would make solar power much more accessible.”

Dhakal, who did his undergraduate work in Nepal, came to Binghamton as a research scientist in 2010 after earning a doctorate at the University of Florida.

Jeffrey Mativetsky, assistant professor of physics, will receive more than $525,000 over five years for the work, which is to begin in July 2016. His research centers on the relationships between nanoscale structure and electrical function in organic materials for solar cells and electronics.

“One of the main things holding back the use of solar cells is the cost associated with them,” he says. “Organic solar cells provide a pathway toward low-cost, clean energy. Organic materials open new possibilities because they are lightweight and mechanically flexible, making it possible, for example, to integrate them into curved surfaces.”

Organic materials can also be processed near room temperature, Mativetsky notes, which is another factor that makes them attractive for flexible electronics.

Mativetsky, who blends principles of physics, chemistry and engineering in his research, says he’s motivated by a desire to work on systems that are relevant to society. He’d like to see solar cells integrated into disaster relief tents, for instance.

In his laboratory, students work at a 16-foot-long, nitrogen-filled glovebox as vacuum pumps vibrate and several solutions swirl in vials on a countertop stir plate. The glovebox maintains an environment a bit above atmospheric pressure, with less than 1 part per million of oxygen and humidity. Mativetsky has two atomic force microscopes, and his team uses additional equipment at Binghamton’s Analytical and Diagnostics Laboratory.

Mativetsky received seed funding through Binghamton’s Transdisciplinary Areas of Excellence program, which encourages work across multiple fields of inquiry and counts smart energy as a special area of interest. The preliminary results obtained by Mativetsky with fellow Binghamton physicist Joon Jang and chemist Alistair Lees provided a foundation for the NSF proposal. “We made it to the start line,” Mativetsky says. “Now we can do the research we set out to do.”

The core of that research will focus on molecule-based nanowires, filaments that are far, far thinner than a human hair and which often have special properties not found in materials at larger scales. Mativetsky is especially interested in how electric charge moves through these nanomaterials.

“We’re investigating the fundamentals of how nanoscale structuring affects charge photogeneration and charge transport,” he says.

Mativetsky believes these nanowires could improve organic solar cell performance and enable the manufacture of flexible solar cells that are thinner than a sheet of paper. Such solar cells might be less efficient than traditional ones made with silicon, he says, but they could produce more energy per gram of material.

Mativetsky, a native of Montreal who earned a doctorate in physics from McGill University in 2006, held post-doctoral fellowships at the Supramolecular Science and Engineering Institute in France and at Princeton University before joining Binghamton’s faculty in 2012.

He is already the recipient of another $300,000 NSF grant, which supports research into graphene oxide with potential applications in flexible electronics, energy storage, sensors, composite materials and biomedical engineering.

The new designs don’t make biological solar cells practical, yet. But they do take them out of the realm of “absurd” and place them squarely in the realm of “someday soon.”

Here’s the challenge:

Current photovoltaic cells generate watts of energy per square centimeter. A solar chip about the size of your fingernail can power a simple handheld calculator. Existing biological cells — which use photosynthesis to generate electricity — produce picowatts per square centimeter — a trillionth of a watt. To power that same calculator, the cells would stretch 20 meters wide and from Binghamton to Ireland. Absurd.

Choi’s first biological solar cell produces a million times more energy, microwatts per square centimeter, so the calculator could operate with a solar panel that fits on a trailer home roof — just 20 meters by 5 meters. His findings were recently published in the Royal Society of Chemistry’s journal Lab on a Chip.

And Choi’s latest experiment churns out milliwatts per square centimeter — reducing the calculator’s solar panel to a backpack-sized 8 inches by 20.

That brings it into the range of practical application, says Hongseok “Moses” Noh, an engineer and professor at Drexel University who specializes in lab-on-a-chip technology and applications. “Milliwatt power should be sufficient to meet those needs,” Noh says. “But the device, so far, is too big for hand-held systems, honestly.”

If Choi can reduce the cell to a tenth of its size while maintaining milliwatt power density, it would be enough to power hand-held blood analysis devices or air-testing machines. “This is one of very few miniaturized bio-solar products,” Noh says, and it’s worth following Choi’s progress.

What makes Choi’s approach different? Existing biological solar cells use a thin strip of gold or indium tin oxide as an anode between the bacteria and an air cathode. Not very efficient, and the bacteria eventually die because they lack air.

Choi uses a carbon anode immersed in the bacteria-laden fluid — a pretty peridot green in a lab flask. More efficient, and because the solution has access to air, it’s self-sustaining. It also uses the plant’s natural respiration to draw energy from the sugars in the cells to keep power up even if light is low.

Choi, an assistant professor of electrical and computer engineering, says he doesn’t understand why one form of cyanobacteria works better than another, or why a mixture of cyanobacteria and heterotrophic bacteria work even better than a single variety. His last biology class was in high school.

“I have no idea about microbiology; I just bought the bacteria and followed the instructions to culture it,” he says. But millions of bacteria species abound, and he plans to experiment to find the most productive combination.

Or, he suggests, he might work with bioengineers to develop a bacterium with its photosynthetic engine on the cell’s surface instead of deep in its heart. That would be another order of magnitude more productive because less energy would be wasted just going from the heart of the cell to its exterior. He has received seed funding from Binghamton’s Transdisciplinary Area of Excellence in smart energy to continue this work.

Choi says he’s confident he’ll eventually reach watt-level energy density, comparable to photovoltaic cells. “I can get that,” he says. “We have room for improvement.”

Instead of going home to Brooklyn, Cuiping “Becky” Deng spent last summer in Binghamton investigating the possibilities of solar energy storage.

As a participant in a National Science Foundation-funded Research Experience for Undergraduates (REU) program, Deng worked closely with a doctoral candidate at the Center for Autonomous Solar Power. For nine weeks, she worked alongside Navjot Kaur Sidhu, building and testing a capacitor that could point the way toward the next generation of energy-storage devices.

“Navjot was very helpful, teaching me how to use all this equipment, how to analyze my data, how to present my findings in a poster,” says Deng, a Binghamton University senior majoring in electrical engineering. “She guided me along, step by step, and once I learned how to actually do that first experiment, she let me mix the chemicals and do the rest by myself. That was the most important lesson, to learn how to work independently.”

Using a combination of metal oxides and conducting polymers, Sidhu is trying to develop a low-cost, high-density, long-lasting supercapacitor to store energy for a variety of applications, especially solar power. Through her own research, Deng has found working examples of supercapacitors that provide energy for solar-powered streetlights in Japan and solar-powered buses in China, where she lived until 2007, when her family moved to New York City.

“This is a very advanced technology, very exciting,” says Deng, who is considering staying in Binghamton for a master’s degree, with a focus on biofuel cells. “When I went to apply for the REU program, this was my first choice, from the beginning. I felt like, ‘Wow, I really want to do this,’ and someday I hope I can apply this knowledge to my own research.”

This year, Deng will continue working with Alok Rastogi, who supervises Sidhu’s research. “I was immediately impressed by her talent for research-oriented projects, and the excitement she felt about this project was exceptional,” says Rastogi, an associate professor of electrical and computer engineering. “For an undergraduate to show such an inclination is remarkable. She will lead a team of three students in a senior design project, and I know she is going to do well. I’m counting on her.”

Mark Fowler, a professor of electrical and computer engineering, has hired Deng as a teaching assistant. “She’s great to work with, one of our best students,” he says. “She was at the top of the class last year, and this year she’s helping in that same class. She’s strong academically and thinks very logically. But the thing that really stands out is the eagerness she projects in everything she does.”

A native of sun-drenched southern India, where daily high temperatures often exceed 100 degrees, discovers that one of the best places to pursue his interest in solar energy is an upstate New York community noted for its cloud cover.

“Since childhood, I have been interested in energy sources that are nonpolluting and are abundant,” says Siva P. Adusumilli, who received his bachelor’s degree in electrical and electronics engineering from Jawaharlal Nehru Technological University. “I did some homework, and I found out about Binghamton University’s Center for Autonomous Solar Power.”

Now Adusumilli is a doctoral student at Binghamton while working as a graduate research associate at the center known as CASP. His focus is on earth-abundant solar materials and nanomaterials.

Some substances, such as silicon, are well-suited for use in solar cells but are costly to process and, therefore, drive up the price of the end product. That limits the cells’ potential for wide usage even though the energy source — the sun — is free, Adusumilli says. He also points out the illogic of having to use great quantities of energy to synthesize materials to be used in products designed to produce or save energy. Research in earth-abundant materials, which are relatively much cheaper, is a growing field.

Adusumilli’s work has been in the synthesis of two such substances for use in thin-film solar cells: iron pyrite (aka “fool’s gold”) and zinc phosphide. Charles R. Westgate, director of CASP, says Adusumilli has won numerous student poster contests and drawn attention from colleagues at prestigious universities for his findings. “He has been successful in achieving high-quality films and nanomaterials like carbon nanotubes and is now optimizing their growth for solar cells,” Westgate says.

Unless the price of raw materials drops, solar energy will not be an appealing option for homeowners, Adusumilli says. “When people put in a solar roof, they think, ‘How long is the payback?’ and, if it’s 20 years …” he says, trailing off with a knowing shrug.

Much of CASP’s funding comes from government agencies, but the center “tries to have communication with industry. Companies like IBM and GE — they know what is needed,” says Adusumilli, who sees himself as a research scientist with a U.S. company after graduation. “Since my childhood, I’ve had the image of me in a research lab coat.”

Binghamton junior Yudi Pardo works on one of the first hurdles: taking the photosynthetic engine out of a plant cell and putting it somewhere it can be used. It’s a problem he has been examining for nearly five years — since before he received his high school diploma.

Now, as a bioengineering major working in Assistant Professor Gretchen Mahler’s laboratory, he’s taking advantage of his opportunities.

He’s working with cyanobacteria ― essentially a blue-green algae — seeking a way to harvest its photosynthetic thylakoids. “How do I extract the complexes in a way where they won’t degrade over time?” he asks.

The solution, eventually, is to graft the thylakoids, which reside in the cell’s inner membrane, onto the cell’s outer membrane. “So when the outer membrane flakes off, you have a working photo system,” he says. “There’s a lot of genetic manipulation.”

Mahler sometimes has difficulty mentoring him, because bio-energy isn’t her research focus. “A lot of students don’t realize they’re into research so early,” Mahler says, much less develop such a specific interest. “He came to me with the project.”

“It’s an interesting problem,” she says, “That’s a good area of research. Nobody has done it.”

It’s an area of research with useful implications. Nathan Nelson of the University of Tel Aviv has developed an ultra-small working solar cell based on a pea plant; it generates 10 volts and with 20 percent efficiency is moderately more efficient than current silicon-based cells.

Nelson and Pardo understand some parts of a plant’s photosynthetic engine are 95 percent to nearly 100 percent efficient. If those parts can be harnessed properly, it could lead to great advances in bio-solar cell efficiency — enough to make them cost effective.

“If we can bring that to the entire device, that would make solar technology more viable for people,” Pardo says. “That really high efficiency on a small scale is what drew me in.”

Biological cells would be faster to construct and largely carbon neutral, although questions remain about how durable biological cells would be, and how they would distribute their energy.

But Pardo, who’s just 20 years old, has time to answer them. “I don’t know specifically where I want to go with this,” he says, citing interests in bio-medicine and medical instrumentation. “But alternative energy has always been at the top of my list.”

Isaac Patka, a sophomore studying electrical engineering, began researching the efficiency of solar cells last summer at Columbia University’s Lab for Unconventional Electronics (CLUE). At CLUE, Patka also developed kits for an upper-level class to use in a lab studying displays such as the electroluminescent display, used in backlights of digital watches, and LED screens used in cell phones.

“My role in that was to look at the lab kits that they currently have and to improve them,” the Albany native says. “Some of their circuit boards weren’t working so I designed a new circuit.”

Patka’s work at CLUE included studying organic LED displays. Organic electronics use small organic molecules that behave like a semiconductor, the electricity-conducting material that Patka describes as the “basis for how all electronics work.”

“The organic materials are easier to process, easier to work with in a lab, and they’re a lot cheaper,” Patka says. “The No. 1 focus that I want to get more into is improving the efficiency of organic solar cells, and there are a lot of different ways that you can do that.”

At Binghamton, Patka has begun that focus in a research group under the direction of Peter Borgesen, a professor in the systems science and industrial engineering department. Last semester, Patka learned how to perform stress tests to evaluate the durability of the layers of organic solar cells.

“The overall goal is to produce solar cells with a good balance between cost, efficiency and long-term reliability,” Borgesen says. “I work with both juniors and seniors, but Isaac is the first to approach me already as a sophomore, and I am impressed.”

Patka plans to continue researching organic solar cells with Borgesen’s group, and he would also like to work with Binghamton’s Center for Autonomous Solar Power (CASP) to investigate the properties of solar cells. “What I would like to do is work with fabricating solar cells for the CASP and do some characterization or improve the fabrication process,” he says.

Improving solar cells can help military operations, researchers far from a grid power source and people in regions such as central Africa that lack adequate sources of energy. “I think it’s important because as the technology is improved and as it will get cheaper and cheaper, it will be able to provide people away from the grid a source of power,” Patka says.

Patka says a week-long program at the U.S. Naval Academy inspired him to become an engineer. “We got to tour some of their research labs,” he says, “and that just got me interested in technical things, and development of research and building practical things.”

U.S. Sen. Charles E. Schumer and Rep. Maurice D. Hinchey said they believe CASP can help to address the national energy crisis as well as lead to the establishment of companies that will create more jobs in upstate New York.

“We are very grateful to Senator Schumer and Congressman Hinchey for their support in securing this funding and for their continuing support of the University,” Binghamton University President Lois B. DeFleur said. “This is an exciting investment in the University and yet another step in the advancement of the Center of Excellence and its research. It is vital that we look at long-term future energy generation from solar power, and Binghamton University is the right place to do just that.”

CASP will address the scientific challenges of reducing the cost of solar power and enhancing energy efficiency. The multidisciplinary center will draw expertise from engineering, computer science, chemistry and physics to focus on areas such as solar conversion efficiency, storage capabilities, solar module stability and power system cost reduction.

CASP will also work with industry to develop new technologies for defense, energy, aerospace, consumer and industrial markets by focusing on solar power sources integrated with new product designs. Potential applications include transportation communication systems, power generation for buildings and devices that will charge cell phone and laptops without the use of batteries.

“A place like this is the hope of the future of the Southern Tier and of America,” said Schumer, who added that he feels that we have a “moral imperative” to advance research on solar energy.Hinchey said he expects to seek additional federal funding for the center in the future. “We need – in the U.S. and frankly around the world – a new industrial revolution,” he said.

Building on the expertise of S3IP, which incorporates the Center for Advanced Microelectronics Manufacturing and the Integrated Electronics Engineering Center, CASP will develop thin film solar modules. Mimicking nature’s own energy-conversion processes, these ultra thin technologies will allow for the design of layered devices that capture all frequencies of the solar spectrum.

Gerald Sonnenfeld, vice president for research, noted that CASP builds on the University’s and the region’s historic strengths. Binghamton, he said, has become a model in terms of building collaborations among government, industry and academia.

“We are committed to the development of unique projects that can improve people’s lives,” Sonnenfeld said.

Using a sustainable model that demands that the individual device will generate much more energy in one year than it takes to manufacture, CASP researchers will be able to develop new and cost-effective applications.

“We all feel the pinch of rising energy costs and, as a society, need to explore alternatives,” said Seshu Desu, dean of the Thomas J. Watson School of Engineering and Applied Science and CASP director. “At the Watson School, our faculty and students are working on addressing the greatest challenges of our technology-intensive society and harnessing low-cost alternative energy sources is at the forefront of our priorities.”