The Meetup will start at 12:00h UTC / 14:00 CEST, click here to check your local time.
The schedule is in UTC time!!!
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Meetup Presentation
This online seminar brings the scientific conference gathering to the desktops or smartphones of scientists worldwide. Researchers can present their work and keep up with cutting-edge research in the field while reducing their carbon footprint, improve the work-life balance and keep the sense of community.
It will consist of two parts, in which interaction will be the main force:
- The Oral Session will consist on a few short broadcasted talks led by Invited Speakers, followed by a time for questions from the public driven by a moderator.
- ePoster Session, where attendees and authors can share their ideas and get feedback from their colleagues worldwide through a chatroom.
All participants can join and present here their work. Due to the short format of the meeting (with few oral contributions), we encourage senior researchers to present ePoster, and of course we expect enthusiastic participation of junior researchers.
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Contemporary Stability Challenges in Hybrid Perovskite Photovoltaics
This conference will gather experts from different disciplines of chemistry, physics, and engineering to create a unique online forum for discussing some of the contemporary challenges associated with the limited operational stability of hybrid perovskites. These challenges are particularly relevant in hybrid perovskite photovoltaics, stimulating the development of innovative strategies to understand the underlying degradation mechanisms and address them. This conference will thereby open discussions towards deepening the understanding of the nature of instabilities in hybrid perovskite materials and the corresponding solar cells from the perspective of structural properties and optoelectronics, as well as device operation.
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G-I1
Perovskite solar cells (PSCs) have demonstrated impressive performance, while their operation stability still requires substantial improvements before this technology can be successfully commercialized. There is a growing evidence that stability of PSCs is strongly dependent on the interface chemistry between the absorber films and adjacent charge transport layers, while the exact mechanistic pathways remain poorly understood.
Here we present a systematic approach for decoupling the degradation effects induced by the top electron transport layer (ETL) of the fullerene derivative PC61BM and various bottom hole-transport layer (HTL) materials assembled in p-i-n perovskite solar cells configurations. We show that chemical interaction of MAPbI3 absorber with PC61BM most aggressively affects the operation stability of solar cells. However, washing away the degraded fullerene derivative and depositing fresh ETL leads to restoration of the initial photovoltaic performance when bottom perovskite/HTL interface is not degraded. Following this approach and refreshing ETL after light soaking of the samples and before completing the solar cell architectures, we were able to compare the photostability of stacks with various HTLs. It has been shown that PEDOT:PSS and NiOx induce significant degradation of the adjacent perovskite layer under light exposure, while PTAA provides the most stable perovskite/HTL interface. ToF-SIMS analysis of fresh and aged samples allowed us to identify chemical origins of the interactions between MAPbI3 and HTLs. The proposed research methodology and the revealed degradation pathways should facilitate future development of efficient and stable perovskite solar cells.
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Giulia is Associate Professor at Physical Chemistry Unit at University of Pavia, leading the PVsquared2 team, and running the European Grant 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 lightinduced dynamical processes underlying the operation of such advanced optoelectronic devices whose understanding is paramount for a smart device development and for contributing to the transition of a green economy.
Giulia received an MS in Physical Engineering in 2008 and obtained her PhD in Physics cum laude in 2012 at the Politecnico of Milan. Her experimental thesis focused on the realisation 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 focused on the developemnt of new generation hybrid perovskite solar cells.
She is author of 90 peer-reviewed scientific papers bringing her h-index to 44 (>13’000 citations), focused on developement and understanding of the interface physics which governs the operation of new generation solar cells.
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 USERN Ambassador for Italy and board member of the Young Academy of Europe.
More can be found at https://pvsquared2.unipv.it.
Weblink: https://people.epfl.ch/giulia.grancini?lang=en
Engineering two-/three- dimensional (2D/3D) perovskite solar cells is nowadays a popular strategy for efficient and stable devices 1-3. However, the exact function of the 2D/3D interface in controlling the long-term device behavior is still obscure.
Here, we reveal a dynamical structural mutation of 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
2D perovskite acts as a sheath to physically protect the 3D underneath. In concomitance, we discovered that the stable 2D perovskite can block ion movement, improving the interface stability on a slow time scale. 2
The judicious choice of the 2D constituents is decisive to control the 2D/3D kinetics and improve the device lifetime, opening a new avenue for perovskite interface design.
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).
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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. She has published more than 130 peer review articles in photophysics and optoelectronics of nanomaterials. In 2012 she has received an ERC starting grant.
Formamidinium lead iodide (FAPbI3) is one of the most extensively studied perovskite materials due to its narrow band gap and high absorption coefficient, which makes it highly suitable solar cells applications. Deposition from a solution containing lead iodide (PbI2) and formamidinium iodide (FAI) or by sequential deposition of PbI2 and FAI usually leads to the formation of films with poor morphology and unstable crystal structure that readily crystallizes into two different polymorphs: the yellow phase and the black phase. I will show that, 2D 2-phenylethylammonium lead iodide (PEA2PbI4) thin films deposited by a scalable doctor-blade coating technique can be used as a growth template for the high-quality 3D FAPbI3 perovskite thin films, by organic cation exchange. I will discuss the structural, morphological and optical properties of these converted 3D FAPbI3 perovskite films, comparing them to the properties of directly deposited 3D FAPbI3 films. The converted FAPbI3 thin films are compact, smooth, highly oriented and exhibit better structural stability in comparison to the directly deposited 3D films. These results not only underscore the importance of the employed deposition techniques in the formation of highly crystalline and stable perovskite thin films but also reveal a strategy to easily obtain very compact perovskite layers using doctor-blade coating.
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As a first step from the lab to the field, operational stability is tested commonly at maximum-power point, constant temperature, and constant illumination. However, in the real world, these parameters vary dependent on weather and climate. Coming closer to application, the energy yield during the course of a year becomes the important figure of merit. In this short talk, I intend to give an overview of effects (day-night cycling, temperature variations, working voltage) to be considered when operating perovskite solar cells under realistic conditions.1 The aging behavior of classical nip devices during real-world temperature-illumination operation conditions serves as an example for examining irreversible and reversible degradation phenomena.2
References
1. Domanski, K., Alharbi, E. A., Hagfeldt, A., Grätzel, M. & Tress, W. Systematic investigation of the impact of operation conditions on the degradation behaviour of perovskite solar cells. Nat. Energy 3, 61–67 (2018).
2. Tress, W. et al. Performance of perovskite solar cells under simulated temperature-illumination real-world operating conditions. Nat. Energy 4, 568–574 (2019).