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EXCITONICS Perovskite Seminar Series
Computational and Experimental Screening of Mixed-Metal Perovskite Compositions*
October 27, 2015 at 12 noon/36-462
Matthew Klug
MIT/Department of Biological Engineering
[klug]
Although solar cells with impressive power conversion efficiencies have been demonstrated
using lead-based metal halide perovskites, there are concerns regarding the inherent
toxicity and long-term stability of these materials. This talk will focus on recent
computational and experimental efforts that explore the feasibility of simultaneously
addressing both of these issues by fabricating active layers with mixed-metal
compositions, where a portion of the metal content in the perovskite film has been
replaced with an alternative, less-toxic metal species. Relevant electronic properties
such as the material band gap, carrier effective masses, and band edge locations were
theoretically evaluated using density functional theory (DFT). By computationally
screening through a series of mixed-metal compositions that spans the periodic table,
several promising candidates were identified that preserve the excellent electronic
properties of the methylammonium lead triiodide perovskite, MAPbI3, while simultaneously
reducing material toxicity. The computational effort was paired with an exhaustive
experimental screening study that systematically evaluated how replacing various amounts
of lead with nine different metal species impacts material and electronic properties as
well as device performance. These findings reveal that introducing a second metal species
can influence film morphology, modify the material band gap, shift the band edge
locations, impact photoluminescence, and improve photovoltaic performance. The aggregate
data provides enough information for us to propose feasible physical mechanisms that
explain trends in performance and are consistent with both empirical observations and
computations. Furthermore, this work will present preliminary results that suggest some
mixed-metal compositions also demonstrate superior resistance to degradation at elevated
temperatures. While further experimentation is required to evaluate whether mixed-metal
compositions would improve performance of solar cells utilizing different device
architectures or perovskite synthesis techniques, this study presents encouraging evidence
that introducing alternative metal species can have beneficial impacts on device
performance and stability, while simultaneously mitigating toxicity.
Matt Klug is a post-doctoral researcher in Prof. Angela Belcher's Biomolecular
Materials Group at MIT, where he studies emerging solution-processed solar cells and
synthesizes photoactive nanocomposites using biological materials.
*This talk is part of the Perovskites Seminar Series organized by Sam Stranks and
sponsored by the Center for Excitonics. For more info contact Sam Stranks:
stranks@mit.edu<mailto:stranks@mit.edu>
Light Refreshments will be served.
The Center For Excitonics Is An Energy Frontier Research Center Funded By The U.S.
Department Of Energy,
Office Of Science And Office Of Basic Energy Sciences
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