Second Severo Ochoa Workshop on Energy Storage and Harvesting

Prof. Anita Ho-Baillie

Anita Ho-Baillie is the John Hooke Chair of Nanoscience at the University of Sydney. She completed her Bachelor of Engineering on Co-op scholarship and PhD (2005) at University of New South Wales. She is a Clarivate Highly Cited Researcher in 2019. Her research interests including engineering of solar materials and devices at nanoscale integrating them onto all kinds of surfaces generating clean energy for different applications. Her achievements include setting solar cell energy efficiency world records in various categories and reporting of highly durable perovskite solar cells placing her research at the forefront internationally.

Durable perovskite solar cells
In this talk, I will talk about the development of low cost and effective methods of encapsulating high efficiency perovskite solar cells and has dramatically boosted their durability so that they now withstand extremes of heat and humidity. Our perovskite solar cells were the first to exceed the strict requirements of International Electrotechnical Commission standards for damp heat and humidity freeze. Such a major breakthrough represents an important step towards commercial viability.

---

Prof. Anna Fontcuberta I Morral

(Barcelona, 1975) és una física catalana, especialitzada en física de la matèria condensada, cap del Laboratori de Materials Semiconductors de l'EPFL de Lausana. Les seves activitats de recerca se centren en enginyeria de nanoestructures semiconductores, en particular de nanofils i en aplicacions fotovoltaiques. Després de llicenciar-se en Física a la Universitat de Barcelona el 1997, feu el màster (1998) i doctorat (2001) a l'École Polytechnique (Palaiseau, França) sota el títol "Study of polymorphous silicon: growth mechanisms, optical and structural properties. Application to Solar Cells and Thin Film Transistors". Va fer una estada postdoctoral d'un any al California Institute of Technology, va obtenir una plaça permanent al CNRS basada a l'Ecole Polytechnique el 2003, i una plaça de professora ajudant a l'EPFL el 2008. Del 2005-2010 va ser cap d'un projecte "Marie Curie Excellence" a l'Institut Walter Schottky de la Technische Universität München, i des del 2014 és professora associada a l'Institut des Matériaux del EPFL. El 2015 va rebre la distinció Emmy Noether de la Societat Europea de Física.

Compound semiconductor nanostructures: synthesis & sustainability aspects
Some compound semiconductors such as GaAs and InGaAsP exhibit a high absorption coefficient in the photon energy of interest for solar energy conversion. Their commercial potential in terrestrial applications is reduced due to the scarcity (and thus high cost) of group III elements such as In and Ga. In this talk we present two approaches to render the use this kind of materials sustainable: a strong reduction in material use through nanostructures and the replacement of group III by group II such as zinc. We find nanostructures also provide a path to increase light collection [1]. We show how II-V compounds such as Zn3P2 exhibit one magnitude higher absorption coefficient than GaAs [2]. We explain how these materials can be fabricated with high crystal quality, opening the path for the creation of alternative and sustainable compound semiconductor solar cells [3,4].
References:
[1] P. Krogstrup et al Nature Photon 7, 306 (2013)
[2] M.Y. Swinkels et al Phys. Rev. Appl. 14, 024045 (2020)
[3] S. Escobar Steinvall et al Nanoscale Horizons 5, 274-282 (2020)
[4] R. Paul et al, Crys. Growth. Des. 20, 3816–3825 (2020)

---

Prof. Susan Trolier McKinstry

Susan Trolier_McKinstry is a professor of Ceramic Science and Engineering and professor of Electrical Engineering at The Pennsylvania State University. She obtained B.S., M.S. and Ph.D. degrees in Ceramic Science and Engineering, all from Penn State. On graduation she joined the faculty there. Trolier-McKinstry is director of Penn State's Nanofabrication Laboratory, a part of Penn State's Materials Research Institute, and has been a faculty member at the University since 1992. She is co-director of the Center for Dielectric and Piezoelectric Studies, a joint Penn State/North Carolina State National Science Foundation Industry/University Cooperative Research Center. She is an associate editor of Applied Physics Letters; a fellow of MRS, the Institute of Electrical and Electronics Engineers, and the American Ceramic Society; and an academician in the World Academy of Ceramics. She previously served as the president of the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society, as well as Keramos and the Ceramic Education Council. She is coauthor of more than 350 papers and holds numerous patents. Among her goals as leader of the MRS board is to actively engage the next generation of materials scientists.

Energy Harvesting with Piezoelectric Films
Hong Goo Yeo¹, Dixiong Wang¹, Tiancheng Xue², Shad Roundy² and Susan Trolier-McKinstry^1
1Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
²Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah, 84112, USA

Harvesting energy from ambient motion using piezoelectric elements is a promising approach to extend the working hours of electronic devices, including wearables, without recharging or replacing batteries. This talk will describe the factors that are used to select thin films for this application, as well as practical implementation of mechanical designs for energy harvesting. Of particular note in materials selection is the energy harvesting figure of merit; for thin film bimorphs this typically corresponds to the product of the charge and voltage piezoelectric coefficients. Appropriate design of domain structure can be used to significantly increase the figure of merit (by up to a factor of ten), though this can constrain the substrate choice.

For applications for the internet of things, resonant energy sources are available, and resonant energy harvesters can be designed. Key parameters in the design are 1) efficiently straining the piezoelectric, while insuring that the material does not exceed elastic limits, 2) tailoring the output voltage to practical levels for the electronics system, 3) matching the resonant frequencies, 4) choosing the optimum electrical loading conditions, and 5) increasing the volume of the piezoelectric. Towards this end, it will be shown that thick piezoelectric films incorporated into devices such as the compliant mechanism harvester significantly outperform (by 5- 55 times) cantilever-based devices. {001} oriented PZT thin films on flexible Ni foil are an excellent candidate for this application.

For scavenging energy from human motion, typical designs for resonant piezoelectric energy harvesters are not suitable to extract electrical energy. Thus, non-resonant piezoelectric energy harvesters such as frequency-up conversion design have been proposed for wearable harvesters. A specific example will be provided of bimorph PZT films sputtered at 550 ~ 585 °C with 10% Pb excess Pb(Zr_0.52,Ti_0.48)O₃ target using an rf power of 88 Watt onto {001} PZT seeded LaNiO₃/HfO₂/Ni foils. Strong {001} orientation of the PT films was confirmed by X-ray diffraction. Both PZT films were dense with columnar grains. Following growth of thick PZT film by high temperature sputtering, one CSD PZT capping layer was used to decrease surface roughness. The PZT films had low dielectric permittivity values near 450, with low loss tangents < 0.04 at 10 kHz. Highly {001} oriented PZT films show well-saturated PE hysteresis loops with large remanent polarization (42 μC/cm²) at 100 Hz. The performance of in-plane plucking designed piezoelectric energy harvester using six rectangular piezoelectric beams will be described. Power levels of >120 μW for running are extrapolated for a wrist-watch size device.

---

Prof. Sossina Haile

Professor of Materials Science and Chemical Engineering Sossina Haile was born on July 28, 1966 in Addis Adeba, Ethiopia. After her family left Africa during an uprising in the 1970s, Haile grew up in Minnesota. She attended the Massachusetts Institute of Technology where she received her B.S. degree in 1986. She went on to receive her M.S. degree from the University of California, Berkeley and her Ph.D. degree from the Massachusetts Institute of Technology in 1992. While in school, Haile received the AT&T Cooperative Research Fellowship and the Fulbright Fellowship to continue her studies. The Fulbright, along with a Humboldt Fellowship the following year, allowed her to study at the Max Palnck Institute für Festkörperforschung in Germany.

Upon receiving her Ph.D. degree, Haile assumed an assistant professorship at the University of Washington, Seattle where she stayed until 1996 when she joined the faculty at the California Institute of Technology. Her research group investigates ionic conduction in solid materials with applications to batteries and fuel cells. Haile is known for her work with the latter - in the 1990s she fabricated the first solid-acid fuel cell in her lab, regarded as a gateway to more powerful, commercial cells. In comparison to other fuel cells, Haile’s is unique for its creation of energy at hot enough to be efficient, but not so hot as to be expensive. In 2003, two of her graduate students created Superprotonic, a company focused on fuel cells, with Haile as science adviser. Most recently, Haile has received recognition for developing new ways of using solar energy to make fuels like hydrogen and methane.

Haile is the recipient of the NSF National Young Investigator Award (1994-1999) and the 2001 J.B. Wagner Award from the High Temperature Materials Division of the Electrochemical Society. Newsweek Magazine named her one of “12 people to watch in 2008,” and in 2010, Haile won both the Chemical Pioneer Award of the American Institute of Chemists and the Chow Foundation Humanitarian Award.

State of the Art in Solid Acid Fuel Cells
The compound CsH₂PO₄ has emerged as a viable electrolyte for intermediate temperature fuel cells. This material is a member of the general class of compounds known as solid acids or acid salts, in which polyanion groups are linked together via hydrogen bonds and monoatomic cations provide overall charge balance. Within this class, several solid acids display a superprotonic transition, at which the compound transforms to a structurally disordered phase of high conductivity. At the transition the conductivity jumps by 3-5 orders of magnitude and the activation energy for proton transport drops to a value of ~ 0.35 eV. The rapid proton transport in the superprotonic phase results from the high degree of polyanion rotational disorder. In the case of CsH₂PO₄ the transition occurs at 228 °C and the conductivity rises to ~ 10^-2 S/cm at 240 °C, enabling fuel cell operation at temperatures between 230 and 260 °C. The physical characteristics of CsH₂PO₄ imply a number of realized and potential advantages for fuel cell operation relative to polymer, solid oxide, and liquid electrolyte alternatives, and have begun to push the technology out of the laboratory into commercial development. We present here an overview of the proton transport characteristics of solid acids and the current status of solid acid fuel cell technology.

---

Derya Baran

King Abdullah University of Science and Technology (KAUST), Materials Science and Enginering, KAUST Solar Center, Thuwal, 23955-6900, Saudi Arabia
Derya, originally from Turkey, is a passionate scientist who received her doctorate degree from Friedrich-Alexander Erlangen-Nürnberg University in Materials Science and Engineering in 2014. Since 2017, she is an assistant professor at King Abdullah University of Science and Technology (KAUST), Saudi Arabia. Her research group (OMEGALAB) focus on engineering organic and hybrid materials for energy harvesting devices. Derya co-authored more than 100 publications and is a recipient of Helmholtz Association postdoc grant in 2015 (joint with Imperial College London). She was selected for MIT Technology Review’s 2018 list of ‘35 Innovators under 35’ for her development of transparent power glass that can generate electricity and block the heat for greenhouses and future buildings. As a scientist and entrepreneur, she strives to be a role model to younger generations.

Energy Harvesting Devices for Printed Electronics
The need for big data that the internet of things (IoT) has created in recent years has turned the focus on integrating the human body in the quest to understand it better, and in turn use such information for detection and prevention of harmful conditions. Applications in which continuous and uninterrupted operation is required, or where the use of external power sources may be challenging demands the use of self-powered autonomous systems. Organic photovoltaic devices are flexible, lightweight, and soft, capable of interacting with the human body and its mechanical demands. Their processability from solutions permits their adaptation to versatile fabrication techniques such as spin coating, roll-to-roll coating and inkjet printing, with benefits including low material usage and freedom of design. In this talk, I will present how organic photovoltaics can be utilized in printed electronics as energy harvesting devices and go through the historical progress of organic/hybrid photovoltaics as well as the main activities that are ongoing in my research lab ‘Omegalab’.
Twitter: @DeryaBaranB
Groupwebsite: omegalabresearch.com

---

Prof. Maria Antonietta Loi

Maria Antonietta Loi studied physics at the University of Cagliari in Italy where she received the PhD in 2001. In the same year she joined the Linz Institute for Organic Solar cells, of the University of Linz, Austria as a post doctoral fellow. Later she worked as researcher at the Institute for Nanostructured Materials of the Italian National Research Council in Bologna Italy.

In 2006 she became assistant professor and Rosalind Franklin Fellow at the Zernike Institute for Advanced Materials of the University of Groningen, The Netherlands. She is now full professor in the same institution and chair of the Photophysics and OptoElectronics group and head of the Department of Mathematics and Natural Sciences of the University College of the University of Groningen. She has published more than 220 peer review articles in photophysics and optoelectronics of nanomaterials. She is cluster leader “Functional materials” of M2i. She serves Deputy editor of Applied Physics Letters and she is member of the international advisory board of several international journals. In 2013 she has received an ERC starting Grant.

Tuning the energetic landscape of Ruddlesden-Popper perovskite films for efficient solar cells
Ruddlesden-Popper perovskite films deposited with different methods and on different substrates show very diverse phase segregation and composition. On PEDOT:PSS, when DMSO is used as solvent, the conventional method based on spin-coating and annealing produces very poor devices, while the vacuum-assisted method proposed here, allows obtaining devices with efficiency up to 14.14%. The reasons for this large difference in efficiency is studied with a combination of optical spectroscopy and microscopy techniques. The conventional method gives rise to 3D-like phase on the top of the film, but dominant n=2 phase with large domains (～40 μm) at the bottom of the film. These n=2 domains are oriented with their inorganic slabs parallel to the substrate and inhibit the charge transport in the vertical direction. Consequently, severe monomolecular and bimolecular charge recombination occurs in the solar cells. Conversely, the vacuum-assisted method yields to films with 3D-like phase dominant throughout their entire thickness, with only a small amount of n≤2 domains of limited dimensions (~3 μm) at the bottom, structure which facilitate charge transport and reduce charge recombination.

---

Prof. Giulia Grancini

Giulia Grancini received an MS in Physical Engineering in 2008 and obtained her PhD in Physics cum laude in 2012 at the Politecnico of Milano. Her experimental thesis focused on the realization of a new femtosecond-microscope for mapping the ultrafast phenomena at organic interfaces. During her PhD, she worked for one year at the Physics Department of Oxford University where she pioneered new concepts within polymer/oxide solar cell technology. From 2012-2015, she was a post-doctoral researcher at the Italian Institute of Technology in Milan. In 2015, she joined the Ecole Polytechnique Fédérale de Lausanne (EPFL) with a Co-Funded Marie Skłodowska-Curie Fellowship. From 2016 to 2019, she has been awarded by the Swiss Ambizione Energy Grant providing a platform to lead her independent research group at EPFL. Since July 2019, Giulia is Associate Professor at Physical Chemistry Unit at University of Pavia, leading the PVsquared2 team, and PI of the ERCStG Project “HYNANO” aiming at the development of advanced hybrid perovskites materials and innovative functional interfaces for efficient, cheap and stable photovoltaics. Within this field, Giulia contributed to reveal the fundamental light-induced dynamical processes underlying the operation of such advanced optoelectronic devices whose understanding is paramount for a smart device optimization.

She is author of 84 peer-reviewed scientific papers bringing her h-index to 42 (>13’000 citations), focused on material design and understanding of the interface physics which governs the operation of organic and hybrid perovskite devices. Recently, she received the USERN prize in Physical Science, the Swiss Physical Society Award in 2018 for Young Researcher and the IUPAP Young Scientist Prize in Optics. She is currently board member of the Young Academy of Europe.

Dynamical 2D/3D Interfaces a boost to Perovskite Solar Cell Stability: what’s behind?
Giulia Grancini (University of Pavia, Department of Chemistry, Italy / GMF, EPFL, Valais Wallis, Switzerland)
Engineering two-/three- dimensional (2D/3D) perovskite solar cells is nowadays a popular strategy for efficient and stable perovskite solar cells ^1-3.
However, the exact function of the 2D/3D interface in controlling the long-term device behavior and the interface physics therein are still obscure.
Here I will discuss the 2D functions which can simultaneously act as surface passivant, electron blocking layer, a sheath to physically protect the 3D underneath, but also impact on the ion movement and charge accumulation. We found a peculiar dynamical structural mutation happening at the 2D/3D interface: the small cations in the 3D cage move towards the 2D layer, which acts as an ion scavenger. If structurally stable, the 2D physically blocks the ion movement at the interface boosting the device stability. Otherwise, the 2D embeds them, dynamically self-transforming into a quasi-2D structure. ²
In concomitance, we discovered that the stable 2D perovskite can block ion movement, improving the interface stability on a slow time scale. ^2,4
The judicious choice of the 2D constituents is decisive to control the 2D/3D kinetics and improve the device lifetime, but also can impact on the interface energetics, which can vary and influence the interface processes and ultimately device open circuit voltage. This knowledge turns fundamental for device design, opening a new avenue for perovskite interface optimization.
References
[1] J.-P. Correa-Baena et al., Science 358, 739–744 (2017).
[2] A. Sutanto et al. J. Mater. Chem. A 8, 2343-2348 (2020).
[3] V. Queloz et al. J. Phys. Chem. Lett. 10, 19, 5713-5720 (2019).
[4] A. Sutanto et al. Nano Lett 20, 3992-3998 (2020)
Acknowledgements I acknowledge the “HY-NANO” project that has received funding from the European Research Council (ERC) Starting Grant 2018 under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 802862).

---

Prof. Ana Claudia Arias

Prof. Arias received her PhD in Physics from the University of Cambridge, UK in 2001. Prior to that, she received her master and bachelor degrees in Physics from the Federal University of Paraná in Curitiba, Brazil in 1997 and 1995 respectively. She joined the University of California, Berkeley in January of 2011. Prof. Arias was the Manager of the Printed Electronic Devices Area and a Member of Research Staff at PARC, a Xerox Company. She went to PARC, in 2003, from Plastic Logic in Cambridge, UK where she led the semiconductor group. Her research focuses on the use of electronic materials processed from solution in flexible electronic systems. She uses printing techniques to fabricate flexible large area electronic devices and sensors.

Power sources for flexible electronic devices
Electronic systems present different functionalities, requirements, form factors and lifetime, but share a need for a power source. We have been developing flexible medical devices that are based on solution processed materials and printing technologies. Our devices are designed to improve signal to noise ratio, minimize waste of materials during the fabrication process and match the human body providing comfort. In this talk, I will discuss the efforts made towards including flexible batteries into medical wearable devices, as well as an analysis on how energy harvesting can play a role on increasing the charge time of wearable devices.

---

Shchedule (Barcelona)	Speaker	Energy Area
14:50-15:00	Monica Lira-Cantu Zakya Kafafi Welcome
15:00-15:30	Anita Wing Yi Ho-Baillie Durable perovskite solar cells	Organic/Perovskite Photovoltaics
15:30-16:00	Anna Fontcuberta i Morral Compound semiconductor nanostructures: synthesis & sustainability aspects	Inorganic Photovoltaics
16:00-16:30	Susan Trolier McKinstry Energy Harvesting with Piezoelectric Films	Energy Harvesting with Piezoelectric Materials
16:30-17:00	Sossina Haile State of the Art in Solid Acid Fuel Cells	Fuel Cells
17:00-17:30	Derya Baran Energy Harvesting Devices for Printed Electronics	Thermoelectrics For Energy Harvesting / Organic/Perovskite Photovoltaics
17:30-17:45	BREAK
17:45-18:15	Maria Antonietta Loi Tuning the energetic landscape of Ruddlesden-Popper perovskite films for efficient solar cells	Organic/Perovskite Photovoltaics
18:15-18:45	Giulia Grancini Dynamical 2D/3D Interfaces a boost to Perovskite Solar Cell Stability: what’s behind?	Organic/Perovskite Photovoltaics
18:45-19:15	Ana Claudia Arias Power sources for flexible electronic devices	Batteries/supercapacitors
19:15-20:00	Round Table Debra Rolison (USA) Sossina Haile (USA) Giulia Grancini (IT) Ana Fontcuberta (CH)	Female Leadership and Women role models. Balance between male and female responses to challenges and risks. Mentoring and career development. Making scientific research an inclusive world. The role of education and importance of leaning.
20:00-21:00	Poster Session