Tag Archives: Vladimir Bulović

Solar cells and soap bubbles

The MIT team has achieved the thinnest and lightest complete solar cells ever made, they say. To demonstrate just how thin and lightweight the cells are, the researchers draped a working cell on top of a soap bubble, without popping the bubble. Photo: Joel Jean and Anna Osherov

The MIT team has achieved the thinnest and lightest complete solar cells ever made, they say. To demonstrate just how thin and lightweight the cells are, the researchers draped a working cell on top of a soap bubble, without popping the bubble. Photo: Joel Jean and Anna Osherov

That’s quite a compelling image and it comes to us courtesy of researchers at MIT (Massachusetts Institute of Technology). From a Feb. 25, 2016 MIT news release (also on EurekAlert),

Imagine solar cells so thin, flexible, and lightweight that they could be placed on almost any material or surface, including your hat, shirt, or smartphone, or even on a sheet of paper or a helium balloon.

Researchers at MIT have now demonstrated just such a technology: the thinnest, lightest solar cells ever produced. Though it may take years to develop into a commercial product, the laboratory proof-of-concept shows a new approach to making solar cells that could help power the next generation of portable electronic devices.

Bulović [Vladimir Bulović ], MIT’s associate dean for innovation and the Fariborz Maseeh (1990) Professor of Emerging Technology, says the key to the new approach is to make the solar cell, the substrate that supports it, and a protective overcoating to shield it from the environment, all in one process. The substrate is made in place and never needs to be handled, cleaned, or removed from the vacuum during fabrication, thus minimizing exposure to dust or other contaminants that could degrade the cell’s performance.

“The innovative step is the realization that you can grow the substrate at the same time as you grow the device,” Bulović says.

In this initial proof-of-concept experiment, the team used a common flexible polymer called parylene as both the substrate and the overcoating, and an organic material called DBP as the primary light-absorbing layer. Parylene is a commercially available plastic coating used widely to protect implanted biomedical devices and printed circuit boards from environmental damage. The entire process takes place in a vacuum chamber at room temperature and without the use of any solvents, unlike conventional solar-cell manufacturing, which requires high temperatures and harsh chemicals. In this case, both the substrate and the solar cell are “grown” using established vapor deposition techniques.

One process, many materials

The team emphasizes that these particular choices of materials were just examples, and that it is the in-line substrate manufacturing process that is the key innovation. Different materials could be used for the substrate and encapsulation layers, and different types of thin-film solar cell materials, including quantum dots or perovskites, could be substituted for the organic layers used in initial tests.

But already, the team has achieved the thinnest and lightest complete solar cells ever made, they say. To demonstrate just how thin and lightweight the cells are, the researchers draped a working cell on top of a soap bubble, without popping the bubble. The researchers acknowledge that this cell may be too thin to be practical — “If you breathe too hard, you might blow it away,” says Jean [Joel Jean, doctoral student] — but parylene films of thicknesses of up to 80 microns can be deposited easily using commercial equipment, without losing the other benefits of in-line substrate formation.

A flexible parylene film, similar to kitchen cling-wrap but only one-tenth as thick, is first deposited on a sturdier carrier material – in this case, glass. Figuring out how to cleanly separate the thin material from the glass was a key challenge, explains Wang [Annie Wang, research scientist], who has spent many years working with parylene.

The researchers lift the entire parylene/solar cell/parylene stack off the carrier after the fabrication process is complete, using a frame made of flexible film. The final ultra-thin, flexible solar cells, including substrate and overcoating, are just one-fiftieth of the thickness of a human hair and one-thousandth of the thickness of equivalent cells on glass substrates — about two micrometers thick — yet they convert sunlight into electricity just as efficiently as their glass-based counterparts.

No miracles needed

“We put our carrier in a vacuum system, then we deposit everything else on top of it, and then peel the whole thing off,” explains Wang. Bulović says that like most new inventions, it all sounds very simple — once it’s been done. But actually developing the techniques to make the process work required years of effort.

While they used a glass carrier for their solar cells, Jean says “it could be something else. You could use almost any material,” since the processing takes place under such benign conditions. The substrate and solar cell could be deposited directly on fabric or paper, for example.

While the solar cell in this demonstration device is not especially efficient, because of its low weight, its power-to-weight ratio is among the highest ever achieved. That’s important for applications where weight is important, such as on spacecraft or on high-altitude helium balloons used for research. Whereas a typical silicon-based solar module, whose weight is dominated by a glass cover, may produce about 15 watts of power per kilogram of weight, the new cells have already demonstrated an output of 6 watts per gram — about 400 times higher.

“It could be so light that you don’t even know it’s there, on your shirt or on your notebook,” Bulović says. “These cells could simply be an add-on to existing structures.”

Still, this is early, laboratory-scale work, and developing it into a manufacturable product will take time, the team says. Yet while commercial success in the short term may be uncertain, this work could open up new applications for solar power in the long term. “We have a proof-of-concept that works,” Bulović says. The next question is, “How many miracles does it take to make it scalable? We think it’s a lot of hard work ahead, but likely no miracles needed.”

Here’s a link to and a citation for the paper,

In situ vapor-deposited parylene substrates for ultra-thin, lightweight organic solar cells by Joel Jean, Annie Wang, Vladimir Bulović. Organic Electronics Volume 31, April 2016, Pages 120–126 doi:10.1016/j.orgel.2016.01.022

This paper is behind a paywall.

MIT (Massachusetts Institute of Technology) signs agreement with Mexican university, Tecnológico de Monterrey

The deal signed by the Massachusetts Institute of Technology (MIT) and one of the largest universities in Latin America covers a five-year period and its initial focus is on nanoscience and nanotechnology. From a Nov. 3, 2014 news item on Azonano,

MIT has established a formal relationship with Tecnológico de Monterrey, one of Latin America’s largest universities, to bring students and faculty from Mexico to Cambridge [Massachusetts, US] for fellowships, internships, and research stays in MIT labs and centers. The agreement will initially focus on research at the frontier of nanoscience and nanotechnology.

An Oct. 31, 2014 MIT news release, which originated the news item, describes the deal and the longstanding relationship between the two institutions,

The agreement was celebrated today with a signing ceremony at MIT attended by a delegation from Tecnológico de Monterrey that included President Salvador Alva; the chairman of the board of trustees, José Antonio Fernández Carbajal; Mexico’s ambassador to the United States, Eduardo Medina Mora; and Daniel Hernández Joseph, the consul general of Mexico in Boston.

“We feel honored for the confidence that the MIT community has placed in us,” Alva says. “Our goal is to educate even more entrepreneurial leaders with the capacity and the motivation to solve humanity’s grand challenges. Leaders capable of creating and sustaining economic and social value. Leaders that will transform the lives of millions of people.”

The agreement sets the stage for increasing long-term cooperation and collaboration between the two universities with an initial academic program that will enable undergraduates, graduate students, postdocs, and junior faculty from Tecnológico de Monterrey to visit the MIT campus, where they will be embedded in labs and centers alongside MIT faculty and students. The participants will gain direct experience in disciplines and topics that match their interests. The program may change or expand its focus after five years.

“The goal for the first five years is to provide students and scholars from Tecnológico de Monterrey with a world-class research experience in nanoscience and nanotechnology and to accelerate research programs of critical importance to Mexico and the world,” says Jesús del Álamo, the Donner Professor of Electrical Engineering, who will coordinate the program at MIT. “And because faculty hosts of participants in the initial program will be recruited from any MIT academic department with relevant activities, we will be able to accommodate interests in nanoscale research over a very broad intellectual front.”

MIT is currently constructing a new facility, MIT.nano, that will be a key resource for future extensions of the program. The new 200,000-square-foot facility, which is being constructed on the site of Building 12 at the center of the MIT campus, will house state-of-the-art cleanroom, imaging, and prototyping facilities supporting research with nanoscale materials and processes — in fields including energy, health, life sciences, quantum sciences, electronics, and manufacturing.

In honor of the new relationship, the facility’s Computer-Aided Visualization Environment will be named after Tecnológico de Monterrey, says Vladimir Bulović, the Fariborz Maseeh Chair in Emerging Technology and faculty lead for the MIT.nano building project.

“When it is completed, MIT.nano will enable students and faculty from Tecnológico de Monterrey to learn and work in one of the most advanced facilities in the world and will give them invaluable experience at the forefront of innovation,” says Bulović, who is also the associate dean for innovation in MIT’s School of Engineering and co-chair of the MIT Innovation Initiative.

Tecnológico de Monterrey is one of the largest universities in Latin America, with nearly 100,000 high school, undergraduate, and graduate students; 31 campuses in Mexico; and 19 international locations and branches in the Americas, Europe, and Japan. This week’s agreement establishes a new relationship between MIT and Tecnológico de Monterrey, but the two institutions have a shared history.

Tecnológico de Monterrey was founded in 1943 by Eugenio Garza Sada, who graduated from MIT in 1914 with a degree in civil engineering. After studying at MIT, Garza Sada — with his brother, Roberto, who graduated from MIT in 1918 — grew his family’s brewery in Mexico into a company that today is known as FEMSA, the largest beverage company in Mexico and Latin America. Tecnológico de Monterrey’s founding director-general was León Ávalos Vez, a mechanical engineer from the MIT Class of 1929.

“We believe that both MIT and Tecnológico de Monterrey play a leadership role in shaping minds and creating knowledge, in serving as catalysts for innovation, entrepreneurship and economic growth, but they also have a responsibility to address the critical problems in the world,” says Fernández, the chairman of the board of trustees at Tecnológico de Monterrey. “This agreement will encourage the implementation of educational programs and accelerate research in nanotechnology in ways that will truly make a difference.”

The new program will commence next spring, with the first students and faculty targeted to come to MIT next summer [2015].

It’ll be interesting to note if this exchange ever reverses and MIT students start visiting Tecnológico de Monterrey campuses. It seems there’s a quite a selection with 31 in Mexico and 19 in various locations internationally.

MIT.nano: new nanotechnology research hub for 2018 and the Self-Assembly Lab

MIT (Massachusetts Institute of Technology) has released an unheard of (as far as I’m concerned) two announcements about a new building, MIT.nano. The shorter announcement mentions priorities (from an April 30, 2014 news item on Azonano),

“If you have your hands on the right tools,” says MIT President L. Rafael Reif, “we believe even big problems have answers.” And, he adds, “A state-of-the-art nano facility is the highest priority for MIT, because nanoscience and nanotechnology are omnipresent in innovation today.”

The longer announcement (from an April 30,2014 news item on Azonano) gives more details about the proposed building,

MIT.nano will house two interconnected floors of cleanroom laboratories containing fabrication spaces and materials growth laboratories, greatly expanding the Institute’s capacity for research involving components that are measured in billionths of a meter — a scale at which cleanliness is paramount, as even a single speck of dust vastly exceeds the nanoscale. The building will also include the “quietest” space on campus — a floor optimized for low vibration and minimal electromagnetic interference, dedicated to advanced imaging technologies — and a floor of teaching laboratory space. Finally, the facility will feature an innovative teaching and research space, known as a Computer-Aided Visualization Environment (CAVE), allowing high-resolution views of nanoscale features.

The longer announcement made in this April 30, 2014 MIT news release which provides more details about the building, the thinking that went into its location, and its special requirements,

The four-level MIT.nano will replace the existing Building 12, and will retain its number, occupying a space alongside the iconic Great Dome. It will be interconnected with neighboring buildings, and accessible from MIT’s Infinite Corridor — meaning, Bulović [electrical engineering professor Vladimir Bulović] says, that the new facility will be just a short walk from the numerous departments that will use its tools.

Users of the new facility, he adds, are expected to come from more than 150 research groups at MIT. They will include, for example, scientists who are working on methods to “print” parts of human organs for transplantation; who are creating superhydrophobic surfaces to boost power-plant efficiency; who work with nanofluids to design new means of locomotion for machines, or new methods for purifying water; who aim to transform the manufacturing of pharmaceuticals; and who are using nanotechnology to reduce the carbon footprint of concrete, the world’s most ubiquitous building material.

Cleanroom facilities, by their nature, are among the most energy-intensive buildings to operate: Enormous air-handling machinery is needed to keep their air filtered to an extraordinarily high standard. Travis Wanat, the senior project manager at MIT who is overseeing the MIT.nano project, explains that while ventilation systems for ordinary offices or classrooms are designed to exchange the air two to six times per hour, cleanroom ventilation typically requires a full exchange 250 times an hour. The fans and filters necessary to handle this volume of air require an entire dedicated floor above each floor of cleanrooms in MIT.nano.

But MIT.nano will incorporate many energy-saving features: Richard Amster, director of campus engineering and construction, has partnered with Julie Newman, MIT’s director of sustainability. Together, they are working within MIT, as well as with the design and contracting teams, “to develop the most efficient building possible for cleanroom research and imaging,” Amster says.

Toward that end, MIT.nano will use heat-recovery systems on the building’s exhaust vents. The building will also be able to sense the local cleanroom environment and adjust the need for air exchange, dramatically reducing MIT.nano’s energy consumption. Dozens of other features aim to improve the building’s efficiency and sustainability.

Despite MIT.nano’s central location, the floor devoted to advanced imaging technology will have “more quiet space than anywhere on campus,” Bulović says: The facility is situated as far as possible from the noise of city streets and subway and train lines that flank MIT’s campus.

Indeed, protection from these sources of noise and mechanical vibration dictated the building’s location, from among five campus sites that were considered. According to national standards on ambient vibration, Bulović says, parts of MIT.nano will rate two levels better than the standard typically used for such high-quality imaging spaces.

Another important goal of the building’s design — by Wilson Architects in Boston — is the creation of environments that foster interactions among users, including those from different disciplines. The building’s location at a major campus “crossroads,” its extensive use of glass walls that allow views into lab and cleanroom areas, and its soaring lobbies and other common areas are all intended to help foster such interactions.

“Nanoscale research is inherently interdisciplinary, and this building was designed to encourage collaboration,” Bulović says.

The choice of MIT.nano’s central location is not without compromise, Bulović says: There is very limited access to the construction site — only three access roads, each with limited headroom — so planning for the activities of construction and delivery vehicles, and for the demolition of the current Building 12 and construction of MIT.nano, will present a host of logistical challenges. “It’s like building a ship in a bottle,” Bulović says.

But addressing those challenges will ultimately be well worth it, he says, pointing out that an estimated one-quarter of MIT’s graduate students and 20 percent of its researchers will make use of the facility. The new building “signifies the centrality of nanotechnology and nanomanufacturing for the needs of the 21st century. It will be a key innovation hub for the campus.”

All current occupants of Building 12 will be relocated by June, when underground facilities work, to enable building construction, will commence; at that point, fences will be erected around the constriction zone. The existing Building 12 will be demolished in spring 2015 and construction of MIT.nano is slated to begin in summer 2015.

An April 25, 2014 news item on Nanowerk features an MIT researcher and research that seems ideally suited to this building initiative (Note: A link has been removed),

Skylar Tibbits … was constructing a massive museum installation with thousands of pieces when he had an epiphany. “Imagine yourself facing months on end assembling this thing, thinking there’s got to be a better way,” he says. A designer and architect, Tibbits was accustomed to modeling and fabricating his complex, architecturally sophisticated sculptures with computation. It suddenly struck him: “With all this information that was used to design the structure and communicate with fabrication machines, there’s got to be a way these parts can build themselves.”

This idea propelled Tibbits to enroll at MIT for dual master’s degrees in computer science, and design and computation — in pursuit of the idea, Tibbits says, “that you could program everything from bits, to atoms, and even large-scale structures.”

Today, Tibbits is breathing life into this vision. A research scientist in the Department of Architecture, and a TED2012 Senior Fellow, Tibbits has launched the Self-Assembly Lab at MIT, where like-minded engineers, scientists, designers, and architects transform commonplace materials into responsive, “smart” materials that can coalesce to form structures, all on their own. Deploying such novel techniques as 4-D printing in collaboration with Stratasys, a firm at the forefront of three-dimensional modeling, Tibbits is experimenting with new products and processes from nano to human scale. [emphasis mine]

An April 24, 2014 MIT news release expands on this “nano to human scale” research,

Although still in its infancy, Tibbits’s research might someday make a profound impact on building and construction. One project, called Logic Matter, encodes simple decision-making in a materials, using only that substance’s properties, shape, and geometry. Bricks, for instance, could be programmed to analyze their own loading conditions or orientation and might contain blueprints to build a wall or guide someone in the construction process. “We don’t have to change what we build with,” Tibbits says. “We take seemingly dumb materials and make them more responsive by combining them in elegant ways with geometry and activation energy.”

Natural processes — such as the replication of DNA, protein folding, and the growth of geometrically perfect crystals — inspired Tibbits. He knew these systems — which build complex structures extremely efficiently and can replicate and repair themselve — depend on a common formula: a simple sequence of instructions, programmable parts, energy, and some type of error correction. Mastering this recipe opens up a world of useful applications, Tibbits believes.

One illustrative project underway in Tibbits’s lab may lead to more resilient and efficient infrastructure. He is trying to program a type of peristalsis in water pipes, so they contract and relax like muscles. Unlike current pipes, which tend to break and require constant monitoring and energy input, Tibbits’s pipes can expand and shrink in response to changes in water volume, and could eventually undulate to abet flow. The goal is a “self-regulating system,” where pipes could even repair themselves in case of a puncture.

Self-assembling technologies may eventually help build space structures whose components deposit themselves in zero gravity environments without human intervention, and edifices that become more resilient in response to “noisy and potentially dangerous energies” from phenomena like earthquakes, hurricanes, and tsunamis, Tibbits says. These ideas may seem hard to believe, but “there are structures we can’t build today” that demand new approaches, Tibbits says. “We must ask where self-assembly can solve some of the world’s biggest challenges.”

I can’t resist the image MIT has provided,

Skylar Tibbits’s fluid crystallization project: Self-assembly holds the promise of breakthroughs in many fields. Photo: Len Rubenstein Courtesy: MIT

Skylar Tibbits’s fluid crystallization project: Self-assembly holds the promise of breakthroughs in many fields.
Photo: Len Rubenstein Courtesy: MIT

You can visit Tibbits’s MIT Self-Assembly Lab here.