Mercouri Kanatzidis

In 2012, we reported the first solid-state halide perovskite solar cell, introducing a concept that was far from obvious at the time. This Perspective revisits how that idea emerged, the experimental path that led to it, and how the field evolved from those early results. It also helps clarify aspects of the early history that have become blurred over time.
pubs.acs.org/doi/10.1021/ac…⁠�

Metformin isn’t just controlling blood sugar anymore...its spacer conformation is structure-directing a 2D perovskite with a seriously sweet X-ray response!
In our new JACS paper, we show how the conformational asymmetry of the doubly protonated metformin (MF2+) spacer in MFPbI4 drives anisotropic octahedral tilting and an anomalous interlayer registry. The result? High-quality crystals with strong in-plane sensitivity (4020 μC Gyair-1 cm-2) and a low detection limit of 65 nGyair s-1, even across large electrode separations.
Congrats to Taylor Wiggins and Khasim Saheb Bayikadi and the whole team on this structure-to-performance study!
doi.org/10.1021/jacs.6…
#Perovskites #JACS #XrayDetection #2DPerovskites #Metformin

We are very excited to share our new paper in Joule addressing one of the most persistent problems in mixed Br/I wide-band-gap APbI3-xBrx perovskites: light-induced halide phase separation.

Our approach uses dual-pseudohalide alloying with SCN- and OCN-. These chemically distinct anions create heterogeneous, non-additive distortions within the halide sublattice. The resulting cooperative frustration suppresses halide-vacancy formation and raises the barriers to ion migration. This reduces ionic conductivity 5-fold and delays phase segregation 10-fold under accelerated illumination.

The resulting 1.78 eV solar cells reach 20% efficiency and retain 90% of their initial performance after 1,530 h of continuous operation at 65 C. All-perovskite tandems achieve 27.2% efficiency and retain 70% after 600 h at 65 C.

We believe chemical frustration of connected ion-migration pathways offers a powerful design principle for stabilizing mixed-halide perovskites while preserving their optoelectronic quality.

Congratulations to Pronoy Nandi and the entire team!

doi.org/10.1016/j.joul…

The chemistry of low-dimensional metal halides has expanded far beyond the original picture of layered 2D perovskites.

In our new Chemical Reviews article, we survey this increasingly rich family of perovskites, perovskitoids, and related metal halides, asking how connectivity and dimensionality govern their structures and functions.

We examine the roles of composition, octahedral connectivity, structural distortion, and organic-inorganic interactions in controlling optical and electronic properties, stability, thin-film integration, and applications from optoelectronics to radiation detection.

The next frontier is clear: moving from observed trends to reliable design principles that allow us to deliberately create low-dimensional materials with targeted properties.

Congratulations to Taylor Wiggins, Arbor Reynolds, Jared Fletcher, Adam Balvanz, Isaiah Gilley, and Edward Sargent on this major collaborative effort.

doi.org/10.1021/acs.ch…

#Perovskites #MetalHalides #MaterialsChemistry #SolidStateChemistry

Our new JACS paper introduces “dilute soft-cation anchoring” as a chemical strategy for stabilizing moisture-sensitive polar chalcogenides without sacrificing their exceptional nonlinear optical response.

γ-NaAsSe2 is one of the strongest known mid-infrared nonlinear optical materials, with an SHG susceptibility near 590 pm/V, but its moisture sensitivity has limited practical use. We show that combining 5% Sb substitution at the As site with only 1% Ag substitution at the Na site addresses this problem at its structural origin.

Sb stabilizes the polar γ framework, while dilute Ag forms more covalent, chalcogenophilic Ag-Se contacts that locally anchor neighboring chains and suppress moisture-assisted lattice opening. Importantly, this subtle modification preserves the electronic structure responsible for the giant nonlinear response.

Large γ-Na0.99Ag0.01As0.95Sb0.05Se2 single crystals remain stable in ambient conditions for at least 365 days while retaining an SHG susceptibility of approximately 600 ± 15 pm/V.

The central message is that very dilute, chemically targeted substitution can dramatically improve environmental stability without compromising optical performance.

Congratulations to Paribesh Acharyya, Himirkanti Sarkar, and the entire team!

doi.org/10.1021/jacs.6…