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February 19, 2017

Herberger Institute artists, students work with scientists and big data in multidisciplinary projects

Microscopy. Big data. Seismology.

These are just some of the tools faculty and students at ASU’s Herberger Institute for Design and the Arts are using in their research and their work — work that also gives back to technology, science and other disciplines outside of design and the arts.

“The multidisciplinary environment of ASU and the energy and curiosity of the Herberger Institute faculty have fused to create this incredibly rich environment for the intersection of the arts and sciences — and beyond,” said Jake Pinholster, associate dean at the Herberger Institute. “We are rapidly moving to a place where design, the arts, the sciences, engineering and the humanities are drawing from one another to solve big problems and find new areas for exploration.”

Susan Beiner, Joan R. LincolnThe professorship was endowed in 2010 by David and Joan Lincoln, longtime supporters of a number of ASU programs ranging from Lincoln Center for Applied Ethics and the Center for the Study of Religion and Conflict, to those within the arts, law and ASU libraries. Endowed Professor in Ceramics, is teaching a new Arts and Science course in the ASU School of Art this semester.

“The art and science collaboration is an opportunity for art students to become exposed to areas of science to spark new concepts for their art as well as to open their mind to utilizing new techniques and materials,” Beiner said.

In 2015, the Herberger Institute’s School of Art partnered with the ASU ­School of Life Sciences (SOLS) for Sculpting Science, a project where art students worked with faculty in the SOLS Electron Microscopy lab to create works of art that represented electron microscopy images of various materials, from plant parts and pollen to sludge and fired clay pieces. The artists received inspiration for their art, and the scientists saw new ways of presenting their information and communicating their work.



“It was so successful that I decided it needed to be a class,” Beiner said.

The new Art 494/598 course expands on the collaboration with Robert Roberson, associate professor in the School of Life Sciences, and using scanning electron microscopy scans. Students visit multiple labs and research collections in the School of Life Sciences and hear professors present their areas of research.

“In this ongoing relationship, the art students will translate new scientific hypotheses into visual imagery,” Beiner said, “and the scientists will gain rare insight into what their research could look like as real 2-D or 3-D objects.”

Roberson said he’s excited to continue working with the School of Art.

“Collaborations between scientists and artists can result in a beautiful piece of art for the artist and a means of communicating for the scientist: a win-win situation,” he said.

In the same way that Beiner’s students translated scientific scans from the Electron Microscopy lab into sculpture, Jessica Rajko uses dance to present big data beyond its purely technical aspect.

Big data is full of numbers and databases, charts and graphs, terabytes and gigabytes. But when Rajko, an assistant professor in the ASU School of Film, Dance and Theatre, looks at big data, she sees art. Her latest work, “Me, My Quantified Self, and I,” which premiered Feb. 10 at Unexpected Art Gallery in Phoenix, is the culmination of the past two years she spent researching big data.

“I was interested in how we make data tangible so that we can start to build meaningful tangible metaphors about humans’ relationship to data,” Rajko said.

Rajko’s research started with a project called “Vibrant Lives,” funded through seed grants from the Herberger Institute and the ASU Institute for Humanities Research. Rajko and her collaborators built interactive installations where people could feel their own data. In one installation, guests plugged their mobile phones into wearable devices that provided haptic feedback when they scrolled through their information, so they could feel how much data they were using. 

“We were really interested in human experience of data,” Rajko said. “In this research we realized more and more how much people are implicated in big data infrastructures, because really big data is about people. It’s about human activity.”

One way her piece aims to make data feel less elusive is with the example of a giant 20- by 20-foot hand-crocheted net. Through a grant from the city of Tempe, Rajko enlisted the Tempe Needlewielders, a volunteer organization that creates and donates handmade items to local charities, to crochet objects onto the net during the performance.

“I really wanted to think about metaphors for data that more accurately reflect what data feels and looks like, which is messy and improvised,” Rajko said. “Having these women crocheting and building and growing this net live through the performance harnessed a lot of what I see as the behaviors of data.” 

By creating these new metaphors and exploring the everyday experience with data, she’s reframing big data, both for a new audience and for those inside the bubble.

“Technology always feels like an insider’s game — we often feel like you have to be a computer scientist to understand,” Rajko said. “The arts in this particular case offer a different type of dialogue around technology, one that feels like it doesn’t talk at people but includes them in it.”

To expand that dialogue, when her show premiered the weekend included a facilitated group discussion about digital human rights, privacy concerns and decolonizing approaches to data use as well as personal cyber-consultations on protecting your data with ASU’s Global Security Initiative.

Lance Gharavi, assistant director of theatre in the School of Film, Dance and Theatre, also uses art to reach a wider audience. In May, Gharavi will present an hourlong performance piece all about the Earth’s core, called “Beneath.” In the vein of Radiolab or Cosmos, the show is a family-friendly scientific exploration of the Earth’s deep interior.

“People will hopefully leave understanding things about the science of the Earth’s material that they didn’t know before, and they will have had a great time,” Gharavi said. “We all gaze up into the sky and into the stars and wonder about what’s up there. We know the mass of Jupiter’s moons. We know what the atmosphere of Venus is made of. We know what the center of galaxy smells like; seriously, we do. But we know almost nothing about the what’s a few hundred miles underneath our feet. ... That’s what the show is about — that mystery of what lies beneath.”

Gharavi, who is working with geophysists, seismologists, mineral physicists, geochemists and other scientists at ASU, said he loves telling stories and loves working with scientists to tell their stories — stories about what they’re doing, what they’re learning and what they’re discovering.

“The advantage to the scientists is their work gets communicated to populations they might not have reached otherwise, and that’s in the case of this kind of work that I’m doing here, which is really about communicating science in a sort of discursive way,” he said.

The performance is part of a larger collaboration between the Herberger Institute’s School of Film, Dance and Theatre and the School of Earth and Space Exploration. Ian Shelanskey, a graduate student in the Herberger Institute studying interdisciplinary digital media and performance, is working with professor Edward Garnero and graduate student Hongyu Lai, both in the School of Earth and Space Exploration, to create a tomography visualization tool.

As Gharavi describes it, seismic tomography is basically taking a CT scan of the planet. The data output is columns of numbers. This new tool creates a picture of the Earth’s interior based on mathematical operations of the data. Scientists can use the tool to adjust the math and see changes in the picture in real time, allowing for deeper analysis and conversation.

Gharavi said this kind of interdisciplinary work is beneficial to everyone.

“The scientists and the designers and the artists that I work with all have different sets of training and skills and specialized knowledges,” he said. “Those are different among us, but we all have a passion for asking questions and finding answers and solving problems, and that’s what we do.”

 

Top photo: Jessica Rajko’s “Me, My Quantified Self, and I” dance work features a 20- by 20-foot hand-crocheted net as a metaphor for big data. Photo by Tim Trumble/Courtesy of the Herberger Institute for Design and the Arts

Sarah A. McCarty

Communications and marketing coordinator , School and Film, Dance and Theatre, Herberger Institute

480-727-4433

 
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ASU, Stanford researchers achieve record-breaking efficiency with tandem solar cell

February 20, 2017

Some pairs are better together than their individual counterparts: peanut butter and chocolate, warm weather and ice cream, and now, in the realm of photovoltaic technology, silicon and perovskite.

As existing solar-energy technologies near their theoretical efficiency limits, researchers are exploring new methods to improve performance — such as stacking two photovoltaic materials in a tandem cell. Collaboration between researchers at Arizona State University and Stanford University has birthed such a cell with record-breaking conversion efficiency — effectively finding the peanut butter to silicon’s chocolate.

The results of their work, published Feb. 17 in Nature Energy, outline the use of perovskite and silicon to create a tandem solar cell capable of converting sunlight to energy with an efficiency of 23.6 percent, just shy of the all-time silicon efficiency record.

“The best silicon solar cell alone has achieved 26.3 percent efficiency,” said Zachary Holman, an assistant professor of electrical engineering at the Ira A. Fulton Schools of Engineering. “Now we’re gunning for 30 percent with these tandem cells, and I think we could be there within two years.”

Silicon solar cells are the backbone of a $30 billion-a-year industry, and this breakthrough shows that there’s room for significant improvement within such devices by finding partner materials to boost efficiency.

The high-performance tandem cell’s layers are each specially tuned to capture different wavelengths of light. The top layer, composed of a perovskite compound, was designed to excel at absorbing visible light. The cell’s silicon base is tuned to capture infrared light.

Perovskite, a cheap, easily manufacturable photovoltaic material, has emerged as a challenger to silicon’s dominance in the solar market. Since its introduction to solar technology in 2009, the efficiency of perovskite solar cells has increased from 3.8 percent to 22.1 percent in early 2016, according to the National Renewable Energy Laboratory.

The perovskite used in the tandem cell came courtesy of Stanford researchers — professor Michael McGehee and doctoral student Kevin Bush, who fabricated the compound and tested the materials.

The research team at ASU provided the silicon base and modeling to determine other material candidates for use in the tandem cell’s supporting layers.

Overcoming challenges with perovskites

Though low-cost and highly efficient, perovskites have been limited by poor stability, degrading at a much faster rate than silicon in hot and humid environments. Additionally, perovskite solar cells have suffered from parasitic absorption, in which light is absorbed by supporting layers in the cell that don’t generate electricity.

“We have improved the stability of the perovskite solar cells in two ways,” said McGehee, a materials science and engineering professor at Stanford’s College of Engineering. “First, we replaced an organic cation with cesium. Second, we protected the perovskite with an impermeable indium tin oxide layer that also functions as an electrode.”

Though McGehee’s compound achieves record stability, perovskites remain delicate materials, making it difficult to employ in tandem solar technology.

“In many solar cells, we put a layer on top that is both transparent and conductive,” said Holman, a faculty member in the School of Electrical, Computer and Energy Engineering. “It's transparent so light can go through and conductive so we can take electrical charges off it.”

This top conductive layer is applied using a process called sputtering deposition, which historically has led to damaged perovskite cells. However, McGehee was able to apply a tin oxide layer with help from chemical engineering professor Stacey Bent and doctoral student Axel Palmstrom of Stanford. The pair developed a thin layer that protects the delicate perovskite from the deposition of the final conductive layer without contributing to parasitic absorption, further boosting the cell’s efficiency.

The deposition of the final conductive layer wasn’t the only engineering challenge posed by integrating perovskites and silicon.

“It was difficult to apply the perovskite itself without compromising the performance of the silicon cell,” said Zhengshan (Jason) Yu, an electrical engineering doctoral student at ASU.

Silicon wafers are placed in a potassium hydroxide solution during fabrication, which creates a rough, jagged surface. This texture, ideal for trapping light and generating more energy, works well for silicon, but perovskite prefers a smooth — and unfortunately reflective — surface for deposition.

Additionally, the perovskite layer of the tandem cell is less than a micron thick, opposed to the 250-micron-thick silicon layer. This means when the thin perovskite layer was deposited, it was applied unevenly, pooling in the rough silicon’s low points and failing to adhere to its peaks.

Yu developed a method to create a planar surface only on the front of the silicon solar cell using a removable, protective layer. This resulted in a smooth surface on one side of the cell, ideal for applying the perovskite, while leaving the backside rough, to trap the weakly absorbed near-infrared light in the silicon.

“With the incorporation of a silicon nanoparticle rear reflector, this infrared-tuned silicon cell becomes an excellent bottom cell for tandems," said Yu.  

Building on previous successes

The success of the tandem cell is built on existing achievements from both teams of researchers. In October 2016, McGehee and post-doctoral scholar Tomas Leijtens fabricated an all-perovskite cell capable of 20.3 percent efficiency. The high-performance cell was achieved in part by creating a perovskite with record stability, marking McGehee’s group as one of the first teams to devote research efforts to fabricating stable perovskite compounds.

Likewise, Holman has considerable experience working with silicon and tandem cells.

“We’ve tried to position our research group as the go-to group in the U.S. for silicon bottom cells for tandems,” said Holman, who has been pursuing additional avenues to create high-efficiency tandem solar cells.

In fact, Holman and Yu published a comment in Nature Energy in September 2016 outlining the projected efficiencies of different cell combinations in tandems.

“People often ask, ‘Given the fundamental laws of physics, what’s the best you can do?’” said Holman. “We’ve asked and answered a different, more useful question: Given two existing materials, if you could put them together, ideally, what would you get?”’

The publication is a sensible guide to designing a tandem solar cell, specifically with silicon as the bottom solar cell, according to Holman.

It calculates what the maximum efficiency would be if you could pair two existing solar cells in a tandem without any performance loss. The guide has proven useful in directing research efforts to pursue the best partner materials for silicon.

“We have eight projects with different universities and organizations, looking at different types of top cells that go on top of silicon,” said Holman. “So far out of all our projects, our perovskite/silicon tandem cell with Stanford is the leader.”

Pete Zrioka

Communications specialist , Ira A. Fulton Schools of Engineering

480-727-5618