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Seminar Speaker: Farzaneh Jahanbakhshi, University of Pennsylvania
February 28 @ 11:00 am – 12:00 pm
Tailoring Interface and Surface Chemistry Toward Stable and Efficient Photovoltaics and Optoelectronics
Abstract
Alongside the ongoing improvements in material synthesis, theoretical and computational approaches have long played a crucial role in advancing efficient, stable, and scalable optoelectronic materials and devices. This has largely been realized through surface and interface engineering, facilitated by the development of atomistic and quantum mechanical models. In the first part of my presentation, I will focus on our predicted models for 2D hybrid organic-inorganic perovskites, based on a series of spacers with varying chemical nature and conformations. We shed light on signature structural characteristics and discuss how in-layer and cross-layer bond formations govern the optoelectronic properties and possibly enhance stabilities in these systems. Through unraveling the underlying physics and complex chemical phenomena, we provide insights into the structural complexities and photophysical properties of these systems and establish design principles for achieving high-efficiency and stable hybrid perovskite solar cells. In the second part, I will introduce a novel strategy to promote phase growth and stabilize the favorable phase in hybrid halide perovskites via fine-tuning interface energetics. Building upon our previous works in surface and interface modification strategies, we investigate the complex surface and interface interactions that occur during deposition and growth, critical to understanding device performance. Performing rigorous quantum mechanical modeling, we develop a phase growth model for formamidinium lead iodide (FAPbI3) that predicts the phase-stability crossover. We uncover the crucial role of ligand migration contingent upon the presence of excess capping ligands in cubic phase stabilization. Next, I will showcase our study on the importance of surface characterization and dynamics on photoluminescence intermittency, one of the biggest challenges in realizing scalable single photon emitters based on inorganic perovskite quantum dots. By unfolding the complex ligand equilibrium and surface phenomena, we provide guidelines for designing efficient and scalable devices. Our research emphasizes the importance of surface and interfacial characterization, and molecular design in advancing the next generation of optoelectronic devices.
Biography
Farzaneh Jahanbakhshi is a Postdoctoral Research Scholar in the School of Arts and Sciences at the University of Pennsylvania and a member of the NSF Center for Integration of Modern Optoelectronic Materials on Demand (IMOD). She received her B.S. (Summa Cum Laude) and M.S. degrees in Structural Engineering, and for her master’s thesis at Sharif University of Technology, developed multi-scale models to investigate the mechanical behavior of heterogeneous crystals. She then pursued a PhD in the Department of Basic Sciences at the École Polytechnique Fédérale de Lausanne (EPFL), where she worked under the supervision of Prof. Ursula Roethlisberger to unravel the complex inter-layer and cross-layer phenomena in hybrid perovskite solar cells. Her comprehensive studies on low-dimensional hybrid perovskites as well as devising and modeling passivation strategies toward surface and interface engineering have made significant contributions to the field. In 2021, Farzaneh joined the group of Prof. Emily Carter at Princeton as a postdoctoral researcher, to employ embedded correlated wavefunction theory to predict CO2 reduction reaction kinetics to uncover superior electro-catalysts. In 2022, Farzaneh started her current position with Prof. Andrew Rappe’s group, where she studies emerging materials for photovoltaics and optoelectronics, such as hybrid perovskites, with the overarching goal of advancing the development of efficient, stable, and scalable devices. She has authored or co-authored 15 peer-reviewed publications, has given several invited and contributed talks at international conferences and has received multiple prestigious fellowships. Drawing from her multi-disciplinary background, the central theme of her research is developing theoretical and computational models at multiple scales to address the underlying physics and intricate chemical phenomena and establish quantum-informed transferrable design rules that can guide experiments and enhance material and device performances across applications.
