The 91探花 is proud to announce that 56 faculty and researchers who completed their work while at 91探花have been named on the list from Clarivate.

The annual list identifies researchers who demonstrated significant influence in their chosen field or fields through the publication of multiple highly cited papers during the last decade. Their names are drawn from the publications that rank in the top 1% by citations for field and publication year in the .

Highly Cited Researchers demonstrate significant and broad influence in their fields of research. The total list includes 7,131 awards from more than 1,300 institutions in 60 countries and regions. This small fraction of the global researcher population contributes disproportionately to extending the frontiers of knowledge and contributing to innovations that make the world healthier, more sustainable and which drive societal impact, according to Clarivate.

The that determines the 鈥渨ho鈥檚 who鈥� of influential researchers is drawn from data and analysis performed by bibliometric experts and data scientists at the Institute for Scientific Information at Clarivate.

The list below includes faculty and researchers whose primary affiliation is with the UW, Fred Hutch Cancer Center, and the Institute for Health Metrics and Evaluation.

Please note: Some of the people on the list are no longer with the 91探花and their current affiliation is noted. This list reflects initial data from Clarivate and may be updated.

Ivan Anishchenko (Vilya)

David Baker

William A. Banks

Gregory N. Bratman

Steven L. Brunton

Guozhong Cao

Ting Cao

Lauren Carter (Gates Medical Research Institute)

Helen Chu

David H. Cobden

Katharine H. D. Crawford

Riza M. Daza

Frank DiMaio

Kristie L. Ebi

Evan E. Eichler

Emmanuela Gakidou

David Ginger

Raphael Gottardo (CHUV)

Alexander L. Greninger

Simon I. Hay

Andrew Hill (Infinimmune)

Eric Huang

Michael C. Jensen (BrainChild)

Neil P.聽 King

C. Dirk Keene

J. Nathan Kutz

Eric H. Larson

Aaron Lyon

Michael J. MacCoss

Brendan MacLean

C. M. Marcus

Julian D. Marshall

Ali Mokdad

Thomas J. Montine (Stanford)

Mohsen Naghavi

Marian L. Neuhouser

Julian D. Olden

Robert W. Palmatier

David Pigott

Hannah A. Pliner (Bristol Myers Squibb)

Ganesh Raghu

Stanley Riddell

Andrea Schietinger (Memorial Sloan Kettering Cancer Center)

Jay Shendure

M. Alejandra Tortorici

Troy R. Torgerson (Allen Institute)

Cole Trapnell

Katherine R. Tuttle

David Veesler

Theo Vos

Alexandra C. Walls (BioNTech SE)

Bryan J. Weiner

Di Xiao

Jie Xiao

Xiaodong Xu

Jihui Yang

鈥淥ur digital technology operates through a series of electronic on-off switches that control the flow of current and voltage,鈥� said , a research scientist at the 91探花. 鈥淏ut our bodies operate on chemistry. In our brains, neurons propagate signals electrochemically, by moving ions 鈥� charged atoms or molecules 鈥� not electrons.鈥�

Implantable devices from pacemakers to glucose monitors rely on components that can speak both languages and bridge that gap. Among those components are OECTs 鈥� or organic electrochemical transistors 鈥� which allow current to flow in devices like implantable biosensors. But scientists long knew about a quirk of OECTs that no one could explain: When an OECT is switched on, there is a lag before current reaches the desired operational level. When switched off, there is no lag. Current drops almost immediately.

A UW-led study has solved this lagging mystery, and in the process paved the way to custom-tailored OECTs for a growing list of applications in biosensing, brain-inspired computation and beyond.

鈥淗ow fast you can switch a transistor is important for almost any application,鈥� said project leader , a 91探花professor of chemistry, chief scientist at the 91探花Clean Energy Institute and faculty member in the 91探花Molecular Engineering and Sciences Institute. 鈥淪cientists have recognized the unusual switching behavior of OECTs, but we never knew its cause 鈥� until now.鈥�

In a published April 17 in Nature Materials, Ginger鈥檚 team at the 91探花鈥� along with Professor at the Okinawa Institute of Science and Technology in Japan and Professor at Zhejiang University in China 鈥� report that OECTs turn on via a two-step process, which causes the lag. But they appear to turn off through a simpler one-step process.

In principle, OECTs operate like transistors in electronics: When switched on, they allow the flow of electrical current. When switched off, they block it. But OECTs operate by coupling the flow of ions with the flow of electrons, which makes them interesting routes for interfacing with chemistry and biology.

The new study illuminates the two steps OECTs go through when switched on. First, a wavefront of ions races across the transistor. Then, more charge-bearing particles invade the transistor鈥檚 flexible structure, causing it to swell slightly and bringing current up to operational levels. In contrast, the team discovered that deactivation is a one-step process: Levels of charged chemicals simply drop uniformly across the transistor, quickly interrupting the flow of current.

Knowing the lag鈥檚 cause should help scientists design new generations of OECTs for a wider set of applications.

鈥淭here鈥檚 always been this drive in technology development to make components faster, more reliable and more efficient,鈥� Ginger said. 鈥淵et, the 鈥榬ules鈥� for how OECTs behave haven鈥檛 been well understood. A driving force in this work is to learn them and apply them to future research and development efforts.鈥�

Whether they reside within devices to measure blood glucose or brain activity, OECTs are largely made up of flexible, organic semiconducting polymers 鈥� repeating units of complex, carbon-rich compounds 鈥� and operate immersed in liquids containing salts and other chemicals. For this project, the team studied OECTs that change color in response to electrical charge. The polymer materials were synthesized by Luscombe鈥檚 team at the Okinawa Institute of Science and Technology and Li鈥檚 at Zhejiang University, and then fabricated into transistors by 91探花doctoral students Jiajie Guo and Shinya 鈥淓merson鈥� Chen, who are co-lead authors on the paper.

鈥淎 challenge in the materials design for OECTs lies in creating a substance that facilitates effective ion transport and retains electronic conductivity,鈥� said Luscombe, who is also a 91探花affiliate professor of chemistry and of materials science and engineering. 鈥淭he ion transport requires a flexible material, whereas ensuring high electronic conductivity typically necessitates a more rigid structure, posing a dilemma in the development of such materials.鈥�

Guo and Chen observed under a microscope 鈥� and recorded with a smartphone camera 鈥� precisely what happens when the custom-built OECTs are switched on and off. It showed clearly that a two-step chemical process lies at the heart of the OECT activation lag.

Past research, including by Ginger鈥檚 group at the UW, demonstrated that polymer structure, especially its flexibility, is important to how OECTs function. These devices operate in fluid-filled environments containing chemical salts and other biological compounds, which are more bulky compared to the electronic underpinnings of our digital devices.

The new study goes further by more directly linking OECT structure and performance. The team found that the degree of activation lag should vary based on what material the OECT is made of, such as whether its polymers are more ordered or more randomly arranged, according to Giridharagopal. Future research could explore how to reduce or lengthen the lag times, which for OECTs in the current study were fractions of a second.

鈥淒epending on the type of device you鈥檙e trying to build, you could tailor composition, fluid, salts, charge carriers and other parameters to suit your needs,鈥� said Giridharagopal.

OECTs aren鈥檛 just used in biosensing. They are also used to study nerve impulses in muscles, as well as forms of computing to create artificial neural networks and understand how our brains store and retrieve information. These widely divergent applications necessitate building new generations of OECTs with specialized features, including ramp-up and ramp-down times, according to Ginger.

鈥淣ow that we鈥檙e learning the steps needed to realize those applications, development can really accelerate,鈥� said Ginger.

Guo is now a postdoctoral researcher at the Lawrence Berkeley National Laboratory and Chen is now a scientist at Analog Devices. Other co-authors on the paper are , a former 91探花postdoctoral researcher in chemistry who is now an assistant professor at the University of Utah; Jonathan Onorato, a 91探花doctoral alum and scientist at Exponent; and Kangrong Yan and Ziqui Shen of Zhejiang University. The research was funded by the U.S. National Science Foundation, and polymers developed at Zhejiang University were funded by the National Science Foundation of China.

For more information contact Ginger at dginger@uw.edu, Luscombe at christine.luscombe@oist.jp and Giridharagopal at rgiri@uw.edu.

The National Science Foundation on Sept. 9 it will fund a new endeavor to bring atomic-level precision to the devices and technologies that underpin much of modern life, and will transform fields like information technology in the decades to come. The five-year, $25 million Science and Technology Center grant will found the 鈥� or IMOD 鈥� a collaboration of scientists and engineers at 11 universities led by the 91探花.

IMOD research will center on new semiconductor materials and scalable manufacturing processes for new optoelectronic devices for applications ranging from displays and sensors to a technological revolution, under development today, that鈥檚 based on harnessing the principles of quantum mechanics.

鈥淚n the early days of electronics, a computer would fill an entire room. Now we all carry around smartphones that are millions of times more powerful in our pockets,鈥� said IMOD director , the Alvin L. and Verla R. Kwiram Endowed Professor of Chemistry at the UW, chief scientist at the 91探花 and co-director of .聽 鈥淭oday, we see an opportunity for advances in materials and scalable manufacturing to do the same thing for optoelectronics: Can we take a quantum optics experiment that fills an entire room, and fit thousands 鈥� or even millions 聽鈥� of them on a chip, enabling a new revolution? Along the way we anticipate IMOD鈥檚 science will help with a few more familiar challenges, like improving the display of the cell phone you already have in your pocket so the battery lasts longer.鈥�

Optoelectronics is a field that enables much of modern information technology, clean energy, sensing and security. Optoelectronic devices are driven by the interaction of light with electronic materials, typically semiconductors. Devices based on optoelectronics include light-emitting diodes, semiconductor lasers, image sensors and the building blocks of quantum communication and computing technologies such as single-photon sources. Their applications today include sensors, displays and data transmission, and optoelectronics is poised to play a critical role in the development of quantum information systems.

But to realize this quantum future, present-day research must develop new materials and new strategies to manufacture them. That鈥檚 where IMOD comes in, Ginger said. Building on advances in the synthesis of semiconductor and , the center will integrate the work of scientists and engineers from diverse backgrounds, including:

• Chemists with expertise in atomically precise colloidal synthesis, characterization and theory, which consist of engineered systems of nanoparticles suspended in a medium
• Materials scientists and mechanical engineers developing methods for the integration, processing and additive manufacturing of semiconductor devices
• Electrical engineers and physicists who are developing new nanoscale photonic structures and investigating the performance limits of these materials for optical quantum communication and computing

鈥淣SF Science and Technology Centers are integrative not only in the sense that they span traditional academic disciplines, but also in the sense that they seek to benefit society by connecting academic research with industrial and governmental needs, while also educating a diverse STEM workforce,鈥� said Ginger. 鈥淭o this end, we鈥檙e extremely lucky to have had the support of an amazing list of external partners across the fields of industry, government and education.鈥�

A partial list of IMOD鈥檚 external partners includes companies such as Amazon, Applied Materials, Corning Incorporated, Microsoft, Nanosys and FOM Technologies, Inc.; government organizations like the National Renewable Energy Laboratory, the Pacific Northwest National Laboratory and the Washington State Department of Commerce; and educational partners including at UW, and the at Georgia Tech.

The center will launch a series of mentorship, team science training and internship programs for participants, including students from underrepresented groups in STEM and first-generation students. Center scientists will also work with high school teachers on curriculum development programs aligned with the and act as 鈥渁mbassadors鈥� to K-12 students, introducing them to STEM careers.

鈥淚n partnership with and the , IMOD is launching a Quantum Training Testbed facility to provide cutting edge training and workforce development opportunities for students from across IMOD鈥檚 participating sites and partners,鈥� said , associate professor of physics and of electrical and computer engineering at the UW, who is IMOD鈥檚 associate director of quantum workforce development. 鈥淲e鈥檙e excited to have such strong support from our partners in the region, allowing us to build on the investments that Washington state has already made in the to support workforce training and economic development. For example, Microsoft plans to donate a cryostat that will allow our students to cool samples down to within a few degrees of absolute zero to study phenomena such as quantum spin physics and decoherence, and we have plans to do so much more for our trainees. Right now, we鈥檙e asking the question: 鈥榃hat is the equipment we wish we had been able to experiment with as students?鈥欌��

The 11 academic institutions that make up IMOD are the 91探花; the University of Maryland, College Park; the University of Pennsylvania; Lehigh University; Columbia University; Georgia Institute of Technology; Northwestern University; the City College of New York; the University of Chicago; University of Colorado at Boulder; and the University of Maryland, Baltimore County.

In addition to Ginger and Fu, other 91探花faculty involved with IMOD include , a 91探花professor of chemistry; , associate professor of mechanical engineering and of materials science and engineering, and technical director of the Washington Clean Energy Testbeds; , associate professor of physics and of electrical and computer engineering; and , professor of chemistry and director of the Molecular Engineering Materials Center. Fu and Majumdar co-chair and are also faculty members with the 91探花. Ginger, Cossairt, Fu, MacKenzie and Gamelin are member faculty at the Clean Energy Institute. Ginger, Fu, Majumdar and Gamelin are faculty researchers with the 91探花.

For more information, contact Ginger at dginger@uw.edu.

In order to understand where strain builds up within a solar cell and triggers the energy loss, scientists must visualize the underlying grain structure of perovskite crystals within the solar cell. But the best approach involves bombarding the solar cell with high-energy electrons, which essentially burns the solar cell and renders it useless.

Researchers from the 91探花 and the FOM Institute for Atomic and Molecular Physics in the Netherlands have developed a way to illuminate strain in lead halide perovskite solar cells without harming them. Their approach, online Sept. 10 in Joule, succeeded in imaging the grain structure of a perovskite solar cell, showing that misorientation between microscopic perovskite crystals is the primary contributor to the buildup of strain within the solar cell. Crystal misorientation creates small-scale defects in the grain structure, which interrupt the transport of electrons within the solar cell and lead to heat loss through a process known as non-radiative recombination.

“By combining our optical imaging with the new electron detector developed at FOM, we can actually see how the individual crystals are oriented and put together within a perovskite solar cell,” said senior author , a 91探花professor of chemistry and chief scientist at the UW-based . “We can show that strain builds up due to the grain orientation, which is information researchers can use to improve perovskite synthesis and manufacturing processes to realize better solar cells with minimal strain 鈥� and therefore minimal heat loss due to non-radiative recombination.”

Lead halide perovskites are cheap, printable crystalline compounds that show promise as low-cost, adaptable and efficient alternatives to the silicon or gallium arsenide solar cells that are widely used today. But even the best perovskite solar cells lose some electricity as heat at microscopic locations scattered across the cell, which dampens the efficiency.

Scientists have long used fluorescence microscopy to identify the locations on perovskite solar cells’ surface that reduce efficiency. But to identify the locations of defects causing the heat loss, researchers need to image the true grain structure of the film, according to first author Sarthak Jariwala, a 91探花doctoral student in materials science and engineering and a Clean Energy Institute Graduate Fellow.

“Historically, imaging the solar cell’s underlying true grain structure has not been possible to do without damaging the solar cell,” said Jariwala.

Typical approaches to view the internal structure utilize a form of electron microscopy called electron backscatter diffraction, which would normally burn the solar cell. But scientists at the FOM Institute for Atomic and Molecular Physics, led by co-authors and , developed an improved detector that can capture electron backscatter diffraction images at lower exposure times, preserving the solar cell structure.

The images of perovskite solar cells from Ginger’s lab reveal a grain structure that resembles a dry lakebed, with “cracks” representing the boundaries among thousands of individual perovskite grains. Using this imaging data, the researchers could for the first time map the 3D orientation of crystals within a functioning perovskite solar cell. They could also determine where misalignment among crystals created strain.

When the researchers overlaid images of the perovskite’s grain structure with centers of non-radiative recombination, which Jariwala imaged using fluorescence microscopy, they discovered that non-radiative recombination could also occur away from visible boundaries.

“We think that strain locally deforms the perovskite structure and causes defects,” said Ginger. “These defects can then disrupt the transport of electrical current within the solar cell, causing non-radiative recombination 鈥� even elsewhere on the surface.”

While Ginger鈥檚 team has previously developed methods to “heal” some of these defects that serve as centers of non-radiative recombination in perovskite solar cells, ideally researchers would like to develop perovskite synthesis methods that would reduce or eliminate non-radiative recombination altogether.

“Now we can explore strategies like controlling grain size and orientation spread during the perovskite synthesis process,” said Ginger. “Those might be routes to reduce misorientation and strain 鈥� and prevent defects from forming in the first place.”

Co-authors on the paper are Hongyu Sun, Gede Adhyaksa, Adries Lof and Loreta Muscarella with the FOM Institute for Atomic and Molecular Physics. The research was funded by the U.S. Department of Energy, U.S. National Science Foundation, the 91探花Clean Energy Institute, , the European Research Council and the Dutch Science Foundation.

For more information, contact Ginger at 206-685-2231 or dginger@uw.edu.

Ginger’s project, which will receive $1.25 million, focuses on developing new methods to alleviate the impact of defects in perovskite solar cells. Perovskites are printable crystalline compounds that can harvest sunlight and convert it to electricity at efficiencies comparable to silicon-based semiconductors used in today’s solar cells. Perovskite solar cells could be printed on roll-to-roll printers like newspapers, reducing manufacturing costs. They are a rapidly growing branch of solar cell research and development, and , operated by the CEI, includes facilities for developing and testing these technologies, including a 30-foot-long multistage roll-to-roll printer.

Atomic-scale defects at perovskite surfaces can reduce their performance. Previous research by Ginger’s group has shown that surface “passivation” 鈥� treating perovskites with different chemical compounds 鈥� can “heal” these defects and improve the efficiency of perovskite solar cells. But when these perovskites are assembled into solar cells, the current-collecting electrodes can create new defects, sapping efficiency. With this new funding, Ginger and his collaborators, Seth Marder and Carlos Silva at Georgia Tech, will develop new chemical passivation strategies, and new charge-collecting materials, that allow perovskites to reach their full potential while still remaining compatible with low-cost manufacturing.

Gamelin’s project, which will receive $200,000, aims to modify solar cells so they can collect high-energy photons more efficiently. Today’s solar cells can convert low-energy photons to electrical power efficiently, but the high-energy variety is converted at very low efficiency 鈥� a major source of energy loss. Gamelin’s team has developed materials that can absorb high-energy photons and emit twice as many low-energy photons, a process termed “quantum cutting.” Their SETO project seeks to integrate these materials as thin layers on the surfaces of solar cells. These surface coatings would essentially “convert” high-energy photons to low-energy photons, allowing their absorption by the solar cell and potentially doubling the current generated by the solar cell. With the new funding, Gamelin’s team will work to develop scalable deposition techniques and prototype large-area solar cells.

The funds from the Department of Energy Solar Energy Technologies Office are part of $28 million in awards for 25 projects in photovoltaics and related fields to boost efficiency and reduce costs in solar energy, according to a March 22 from the office. The first set of selections from this program, announced late last year, included more than $2.3 million awarded to 91探花projects.

###

Solar cells are devices that absorb photons from sunlight and convert their energy to move electrons 鈥� enabling the production of clean energy and providing a dependable route to help combat climate change. But most solar cells used widely today are thick, fragile and stiff, which limits their application to flat surfaces and increases the cost to make the solar cell.

鈥淭hin-film solar cells鈥� could be 1/100^th the thickness of a piece of paper and flexible enough to festoon surfaces ranging from an aerodynamically sleek car to clothing. To make thin-film solar cells, scientists are moving beyond the 鈥渃lassic鈥� semiconductor compounds, such as gallium arsenide or silicon, and working instead with other light-harvesting compounds that have the potential to be cheaper and easier to mass produce. The compounds could be widely adopted if they could perform as well as today鈥檚 technology.

In a published online this spring in the journal , scientists at the 91探花 report that a prototype semiconductor thin-film has performed even better than today鈥檚 best solar cell materials at emitting light.

鈥淚t may sound odd since solar cells absorb light and turn it into electricity, but the best solar cell materials are also great at emitting light,鈥� said co-author and 91探花chemical engineering professor , who is also a faculty member with both the UW鈥檚 and .聽 鈥淚n fact, typically the more efficiently they emit light, the more voltage they generate.鈥�

The 91探花team achieved a record performance in this material, known as a lead-halide perovskite, by chemically treating it through a process known as 鈥渟urface passivation,鈥� which treats imperfections and reduces the likelihood that the absorbed photons will end up wasted rather than converted to useful energy.

鈥淥ne large problem with perovskite solar cells is that too much absorbed sunlight was ending up as wasted heat, not useful electricity,鈥� said co-author , a 91探花professor of chemistry and chief scientist at the CEI. 鈥淲e are hopeful that surface passivation strategies like this will help improve the performance and stability of perovskite solar cells.鈥�

Ginger鈥檚 and Hillhouse鈥檚 teams worked together to demonstrate that surface passivation of perovskites sharply boosted performance to levels that would make this material among the best for thin-film solar cells. They experimented with a variety of chemicals for surface passivation before finding one, an organic compound known by its acronym TOPO, that boosted perovskite performance to levels approaching the best gallium arsenide semiconductors.

鈥淥ur team at the 91探花was one of the first to identify performance-limiting defects at the surfaces of perovskite materials, and now we are excited to have discovered an effective way to chemically engineer these surfaces with TOPO molecules,鈥� said co-lead author , a postdoctoral researcher at the Massachusetts Institute of Technology who conducted this research as a 91探花chemistry doctoral student. 鈥淎t first, we were really surprised to find that the passivated materials seemed to be just as good as gallium arsenide, which holds the solar cell efficiency record. So to double-check our results, we devised a few different approaches to confirm the improvements in perovskite material quality.鈥�

DeQuilettes and co-lead author , who conducted this research as a doctoral student in chemical engineering, showed that TOPO-treating a perovskite semiconductor significantly impacted both its internal and external photoluminescence quantum efficiencies 鈥� metrics used to determine how good a semiconducting material is at utilizing an absorbed photon鈥檚 energy rather than losing it as heat. TOPO-treating the perovskite increased the internal photoluminescence quantum efficiencies by tenfold 鈥� from 9.4 percent to nearly 92 percent.

鈥淥ur measurements observing the efficiency with which passivated hybrid perovskites absorb and emit light show that there are no inherent material flaws preventing further solar cell improvements,鈥� said Braly. 鈥淔urther, by fitting the emission spectra to a theoretical model, we showed that these materials could generate voltages 97 percent of the theoretical maximum, equal to the world record gallium arsenide solar cell and much higher than record silicon cells that only reach 84 percent.鈥�

These improvements in material quality are theoretically predicted to enable the light-to-electricity power conversion efficiency to reach 27.9 percent under regular sunlight levels, which would push the perovskite-based photovoltaic record past the best silicon devices.

The next step for perovskites, the researchers said, is to demonstrate a similar chemical passivation that is compatible with easily manufactured electrodes 鈥� as well as to experiment with other types of surface passivation.

鈥淧erovskites have already demonstrated unprecedented success in photovoltaic devices, but there is so much room for further improvement,鈥� said deQuilettes. 鈥淗ere we think we have provided a path forward for the community to better harness the sun鈥檚 energy.鈥�

Other co-authors are , a postdoctoral researcher at the University of California, Berkeley; , who recently completed his 91探花undergraduate degree in materials science and engineering; and , who just completed his doctoral degree with the 91探花Department of Chemistry and the CEI. The research was funded by the U.S. Department of Energy, the National Science Foundation, the 91探花, the 91探花Clean Energy Institute, the 91探花Molecular Engineering & Sciences Institute and the University of California, Berkeley.

###

For more information, contact Ginger at 206-685-2231 or dginger@uw.edu and Hillhouse at 206-685-5257 or h2@uw.edu.

Grant numbers: DE-SC0013957, DGE-1256082, DE-EE0006710, ECC-1542101.

Many innovations of 21st century life, from touch screens and electric cars to fiber-optics and implantable devices, grew out of research on new materials. This impact of materials science on today’s world has prompted two of the leading research institutions in the Pacific Northwest to join forces to research and develop new materials that will significantly influence tomorrow’s world.

With this eye toward the future, the Department of Energy’s and the announced the creation of the 鈥� or NW IMPACT 鈥� a joint research endeavor to power discoveries and advancements in materials that transform energy, telecommunications, medicine, information technology and other fields. 91探花President and PNNL Director formally launched NW IMPACT during a ceremony Jan. 31 at the PNNL campus in Richland, Washington.

“This partnership holds enormous potential for innovations in materials science that could lead to major changes in our lives and the world,” said Cauce. “We are excited to strengthen the ties between our two organizations, which bring complementary strengths and a shared passion for ground-breaking discovery.”

“The science of making new materials is vital to a wide range of advancements, many of which we have yet to imagine,” said Ashby. “By combining ideas, talent and resources, I have no doubt our two organizations will find new ways to improve lives and provide our next generation of materials scientists with valuable research opportunities.”

The institute builds on a history of successful partnerships between the 91探花and PNNL, including joint faculty appointments and past collaborations such as the , the PNNL-led and a new UW-based . But NW IMPACT is the beginning of a long-term partnership, forging deeper ties between the 91探花and PNNL.

The goal is to leverage these respective strengths to enable discoveries, innovations and educational opportunities that would not have been possible by either institution alone.

“By partnering the 91探花and PNNL together through NW IMPACT, the sum will truly be greater than the parts,” said David Ginger, a 91探花professor of chemistry and chief scientist at the 91探花. 聽“We are joining together our expertise and experiences to create the next generation of leaders who will create the materials of the future.”

Ginger will co-lead the institution in its initial phase with Jim De Yoreo, chief scientist for materials synthesis and simulation across scales at PNNL and a joint appointee at the UW.

Over its first few years, NW IMPACT aims to hire a permanent institute director, who will be based at both PNNL and the UW; create at least 20 new joint UW-PNNL appointments among existing researchers; streamline access to research facilities at the UW’s Seattle campus and PNNL’s Richland campus for institute projects; involve at least 20 new 91探花graduate students in PNNL- 91探花collaborations; and provide seed grants to institute-affiliated researchers to tackle new scientific frontiers in a collaborative fashion.

Some of the areas in which NW IMPACT will initially focus include:

• Materials for energy conversion and storage, which can be applied to more efficient solar cells, batteries and industrial applications. These include innovative approaches to create flexible, ultrathin solar cells for buildings or fabrics, long-lasting batteries for implantable medical devices, catalysts to enable high efficiency energy conversion and industrial processes, and manufacturing methods to synthesize these materials efficiently for commercial applications.
• Quantum materials, such as ultrathin semiconductors or other materials that can harness the rules of quantum mechanics at subatomic-level precision for applications in quantum computing, telecommunications and beyond.
• Materials for water separation and utilization, which include processes to make water purification and ocean desalination methods faster, cheaper and more energy-efficient.
• Biomimetic materials, which are synthetic materials inspired by the structures and design principles of biological molecules and materials within our cells 鈥� including proteins and DNA. These materials could be applicable in medical settings for implantable devices or tissue engineering, and for self-assembled protein-like scaffolds in industrial settings.

“The science of making materials involves understanding where the atoms must be placed in order to obtain the properties needed for specific applications, and then understanding how to get the atoms where they need to be,” said De Yoreo.

NW IMPACT will draw on the unique strengths and talents of each institution for innovative collaborations in these areas. For example, PNNL has broad expertise in materials for improved batteries. The lab also offers best-in-class imaging, NMR and mass spectrometry capabilities at , a DOE Office of Science user facility. DOE supports fundamental research at PNNL in chemistry, physics and materials sciences that are key to materials development. The 91探花brings complementary facilities and equipment to the partnership, such as the and a cryo-electron microscopy facility, as well as expertise in a variety of “big data” research and training endeavors, highly rated research and education programs, and ongoing materials research projects through the National Science Foundation-funded .

###

For more information, contact James Urton with the 91探花News Office at 206-543-2580 or jurton@uw.edu and Susan Bauer with the PNNL News & Media Relations Office at 509-372-6083 or susan.bauer@pnnl.gov.

That conclusion might crop up during divorce proceedings, or describe a diplomatic row. But scientists designing polymers that can bridge the biological and electronic divide must also deal with incompatible messaging styles. Electronics rely on racing streams of electrons, but the same is not true for our brains.

“Most of our technology relies on electronic currents, but biology transduces signals with ions, which are charged atoms or molecules,” said , professor of chemistry at the 91探花 and chief scientist at the UW’s . “If you want to interface electronics and biology, you need a material that effectively communicates across those two realms.”

Ginger is senior author of a published online June 19 in in which 91探花researchers directly measured a thin film made of a single type of conjugated polymer 鈥� a conducting plastic 鈥� as it interacted with ions and electrons. They show how variations in the polymer layout yielded rigid and non-rigid regions of the film, and that these regions could accommodate electrons or ions 鈥� but not both equally. The softer, non-rigid areas were poor electron conductors but could subtly swell to take in ions, while the opposite was true for rigid regions.

Organic semiconducting polymers are complex matrices made from repeating units of a carbon-rich molecule. An organic polymer that can accommodate both types of conduction 鈥� ions and electrons 鈥� is the key to creating new biosensors, flexible bioelectronic implants and better batteries. But differences in size and behavior between tiny electrons and bulky ions have made this no easy task.

Their results demonstrate how critical the polymer synthesis and layout process is to the film’s electronic and ionic conductance properties. Their findings may even point the way forward in creating polymer devices that can balance the demands of electronic transport and ion transport.

“We now understand the design principles to make polymers that can transport both ions and electrons more effectively,” said Ginger. “We even demonstrate by microscopy how to see the locations in these soft polymer films where the ions are transporting effectively and where they aren’t.”

Ginger’s team measured the physical and electrochemical properties of a film made out of poly(3-hexylthiophene), or P3HT, which is a relatively common organic semiconductor material. Lead author Rajiv Giridharagopal, a research scientist in the 91探花Department of Chemistry, probed the P3HT film’s electrochemical properties in part by borrowing a technique originally developed to measure electrodes in lithium-ion batteries.

The approach, electrochemical strain microscopy, uses a needle-like probe suspended by a mechanical arm to measure changes in the physical size of an object with atomic-level precision. Giridharagopal discovered that, when a P3HT film was placed in an ion solution, certain regions of the film could subtly swell to let ions flow into the film.

“This was an almost imperceptible swelling 鈥� just 1 percent of the film’s total thickness,” said Giridharagopal. “And using other methods, we discovered that the regions of the film that could swell to accommodate ion entry also had a less rigid structure and polymer arrangement.”

More rigid and crystalline regions of the film could not swell to let in ions. But the rigid areas were ideal patches for conducting electrons.

Ginger and his team wanted to confirm that structural variations in the polymer were the cause of these variations in electrochemical properties of the film. Co-author , a 91探花associate professor of materials science and engineering and member of the Clean Energy Institute, and her team made new P3HT films that had different levels of rigidity based on variations in polymer arrangement.

By subjecting these new films to the same array of tests, Giridharagopal showed a clear correlation between polymer arrangement and electrochemical properties. The less rigid and more amorphous polymer layouts yielded films that could swell to let in ions, but were poor conductors of electrons. More crystalline polymer arrangements yielded more rigid films that could easily conduct electrons.

These measurements demonstrate for the first time that small structural differences in how organic polymers are processed and assembled can have major consequences for how the film accommodates ions or electrons. It may also mean that this tradeoff between the needs of ion and electrons is unavoidable. But these results give Ginger hope that another solution is possible.

“The implication of these findings is that you could conceivably embed a crystalline material 鈥� which could transport electrons 鈥� within a material that is more amorphous and could transport ions,” said Ginger. “Imagine that you could harness the best of both worlds, so that you could have a material that is able to effectively transport electrons and swell with ion uptake 鈥� and then couple the two with one another.”

If so, then a bioelectronic divorce may not be on the horizon, but better bioelectronic devices and better batteries should be.

Co-authors were 91探花doctoral students Lucas Flagg, Jeff Harrison, Mark Ziffer and Jon Onorato. The work was funded by the National Science Foundation, the 91探花Clean Energy Institute, the Washington Research Foundation and the Alvin L. and Verla R. Kwiram endowed fund in the 91探花Department of Chemistry.

###

For more information, contact Ginger at dginger@uw.edu or 206-685-2331 and Giridharagopal at rgiri@uw.edu or 206-221-4191.

Grant numbers: DMR-1607242, DMR-1533372, DMR-1629369.

DOI: 10.1038/nmat4918

Electrical energy fuels our modern lives, from the computer screen that keeps us up after sunset to the coffee maker that greets us at sunrise. But the electricity underlying our 21^st century world, by and large, is generated at a cost 鈥� through the unsustainable expenditure of fossil fuels. For decades this demand for cheap, fast and non-renewable electricity has promoted pollution and global warming.

The key to reversing this downward spiral is deleting the “non” in “non-renewable electricity.” In a in the journal , an international team shows that cheap energy in the form of solar cells is closer than we think, despite the long history behind the development of this technology.

“The traditional solar cells that are used commercially today stand on the shoulders of 50 years of research and development,” said , 91探花 professor of chemistry and associate director of the 91探花.

Today’s solar cells 鈥� from the roofs of our homes to “” 鈥� are by and large based on the photon-converting properties of silicon crystals. While widespread, this technology is not as cheap and fast to produce as the fossil fuels we exploit today. Ginger, and collaborators 鈥� including scientists at UW, the Massachusetts Institute of Technology and the University of Oxford 鈥� want to upend this dynamic with non-silicon, ultrathin, synthetic crystals that are cheaper, faster and lighter.

The non-silicon crystals they use contain a unique mixture of organic and inorganic Earth-abundant elements. The crystals, termed “perovskites” after their unique arrangement of positively and negatively charged ions, are a promising lead in the next generation of solar cell technology.

“In just a few years of research and development, perovskite solar cells have reached efficiency levels approaching today’s commercial solar cells,” said Ginger.

But high efficiencies of perovskite crystals have only been realized on a small scale in the laboratory. To reach factories and consumers 鈥� especially for solar panels 鈥� they must last at least as long as today’s silicon crystals. That is a challenge that scientists like UW’s are taking on.

“All perovskite crystals have defects 鈥� an inevitable consequence of the fabrication process 鈥� and we’re trying to come up with methods to repair them and improve solar cells,” said deQuilettes, lead author and a graduate student in the Department of Chemistry.

At just 1/100^th the width of a human hair, the perovskite crystals that deQuilettes, Ginger and their colleagues work with are delicate and difficult to perfect. They’re rife with defects that decrease their efficiency, not counting the imperfections they accumulate over time.

deQuilettes and colleagues at MIT, including TED Fellow , sought out various treatments to reverse these adverse effects. In the process, they showed that the photons they shined on the perovskite cells had a therapeutic effect. Exposure to intense visible light increased the energy conversion efficiency of the perovskite crystals 鈥� and deQuilettes has proven why.

“We believe it all comes down to iodine,” said deQuilettes.

Using perovskite crystals synthesized by at Oxford University, deQuilettes and Stranks showed that intense light exposure helped crystals repair themselves by physically transporting iodine during illumination. deQuilettes used two powerful imaging techniques to show that iodine ions within perovskite crystals moved away from intense light. deQuilettes and Ginger hypothesize that the unique chemical environment at the surface of synthetic perovskite crystals explains this movement.

“We think many of the defects in these crystals lie along the surface, and that may cause negatively charged electrons to pile up at the crystal surface,” said deQuilettes.

“If that is the case, then when you shine light on the surface, negatively charged ions within the crystal 鈥� like iodide 鈥� will want to move away,” added Ginger. “That may explain how light helps these crystals heal, at least on a temporary basis.”

Under their experimental methods, light has only a temporary healing effect on the solar cell crystals. But Ginger, deQuilettes and their colleagues want to find processing routes or treatments that make their repairs permanent. Those endeavors 鈥� coupled with methods to expand ultrathin solar cell production 鈥� could make perovskites a viable and sustainable alternative to today’s silicon-based solar cell technologies.

“It’s exhilarating to work in a field that has the potential to revolutionize the solar energy industry,” said deQuilettes. “Now that we are learning how to heal defects, I think we are getting closer and closer to that revolution.”

Other co-authors are Victor Burlakov, Tomas Leijtens and Henry Snaith of Oxford University; Daniel Graham of the UW; and Anna Osherov, Vladimir Bulovic and senior author Samuel Stranks of the Massachusetts Institute of Technology. 91探花research was funded by the U.S. Department of Energy and the National Science Foundation.

###

For more information, contact Ginger at 206-685-2331 and dinger@uw.edu or deQuilettes at聽dwd2@uw.edu.

Grant numbers: DE-SC0013957, DGE-1256082.

One of the fastest-growing areas of solar energy research is with materials called perovskites. These promising light harvesters could revolutionize the solar and electronics industries because they show potential to convert sunlight into electricity more efficiently and less expensively than today鈥檚 silicon-based semiconductors.

These superefficient crystal structures have taken the scientific community by storm in the past few years because they can be processed very inexpensively and can be used in applications ranging from solar cells to light-emitting diodes (LEDs) found in phones and computer monitors.

A in the journal by 91探花 and University of Oxford researchers demonstrates that perovskite materials, generally believed to be uniform in composition, actually contain flaws that can be engineered to improve solar devices even further.

鈥淧erovskites are the fastest-growing class of photovoltaic material over the past four years,鈥� said lead author , a 91探花doctoral student working with , professor of chemistry and associate director of the 91探花.

鈥淚n that short amount of time, the ability of these materials to convert sunlight directly into electricity is approaching that of today鈥檚 silicon-based solar cells, rivaling technology that took 50 years to develop,鈥� deQuilettes said. 鈥淏ut we also suspect there is room for improvement.鈥�

The research team used high-powered imaging techniques to find defects in the perovskite films that limit the movement of charges and, therefore, limit the efficiency of the devices. Perovskite solar cells have so far have achieved efficiencies of roughly 20 percent, compared to about 25 percent for silicon-based solar cells.

In a collaboration made possible by the Clean Energy Institute, the team used a technique called confocal optical microscopy, which is more often used in biology, and applied it to semiconductor technology. They used fluorescent images and correlated them with electron microscopy images to find 鈥渄ark鈥� or poorly performing regions of the perovskite material at intersections of the crystals. In addition, they discovered that they could 鈥渢urn on鈥� some of the dark areas by using a simple chemical treatment.

The images offered several surprises but also will lead to accelerated improvements in the materials鈥� uniformity, stability and efficiency, according to corresponding author Ginger, the Alvin L. and Verla R. Kwiram Endowed Professor of Chemistry and Washington Research Foundation Distinguished Scholar.

鈥淪urprisingly, this result shows that even what are being called good, or highly-efficient perovskite films today still are 鈥榖ad鈥� compared to what they could be. This provides a clear target for future researchers seeking to improve and grow the materials,鈥� Ginger said.

The imaging technique developed by the 91探花team also offers an easy way to identify previously undiscovered flaws in perovskite materials and to pinpoint areas where their composition can be chemically altered to boost performance, Ginger said.

deQuilettes, who spearheaded the project as a , estimates there are more than a thousand laboratories around the world currently researching the semiconducting properties of perovskite materials. Yet there is more work to be done to understand how to consistently make a material that is stable, has uniform brightness and can stand up to moisture without degrading. The 91探花research offers new ways for people to think strategically about how to improve the materials and how to extend their applications to high performance light-emitting devices such as LEDs and lasers.

鈥淭here are so many of us focusing on perovskites, so hopefully this technique will offer some new direction and steer us toward the places we can look to optimize their energy-capturing and emitting potential,鈥� deQuilettes said.

Co-authors of the study are Sarah M. Vorpahl, Hirokazu Nagaoka and Mark E. Ziffer of the 91探花and Samuel D. Stranks, Giles E. Eperon and Henry J. Snaith at Oxford.

Funding for the research was provided by the state of Washington through the 91探花Clean Energy Institute.

For more information, contact 91探花researchers deQuilettes at dwd2@uw.edu and Ginger at dginger@uw.edu and Oxford researchers Stranks at stranks@mit.edu and Snaith at Henry.Snaith@physics.ox.ac.uk.