2020 New's Items

Expanded Analogs of Three-Dimensional Lead-Halide Hybrid Perovskites

D. Umeyama
L. Leppert
B. A. Connor
M. A. Manumpil
J. B. Neaton
H. I. Karunadasa
2020

The expanded analogs of 3D halide perovskites reported herein can hold relatively large aromatic cations in the spacious inorganic sublattice. The band gap of these materials is set by the empty low-lying orbitals of the organic molecules and the filled orbitals of the inorganic components. The molecular nature of the conduction band allows us to electronically dope the materials through simple redox chemistry. Replacing the Pb−X octahedral building unit of AIPbX3 perovskites (X=halide) with a pair of edge-sharing Pb−X...

Metal–Organic Frameworks for Water Harvesting from Air, Anywhere, Anytime

Xu W
Yaghi OM
2020

Water is essential to life. It is estimated that by 2050 nearly half of the world population will live in water stressed regions, due to either arid conditions or lack of access to clean water. This Outlook, written for the general readers, outlines the parameters of this vexing societal problem and presents a solution to the global water challenge. There is plenty of water in the air that potentially can be harvested not only from the desert atmosphere where the humidity is low but also from more humid regions of the world where clean water is needed. In principle, the materials...

Characterizing transition-metal dichalcogenide thin-films using hyperspectral imaging and machine learning

Brian Shevitski
Christopher T. Chen
Christoph Kastl
Tevye Kuykendall
Adam Schwartzberg
Shaul Aloni
Alex Zettl
2020

Atomically thin polycrystalline transition-metal dichalcogenides (TMDs) are relevant to both fundamental science investigation and applications. TMD thin-films present uniquely difficult challenges to effective nanoscale crystalline characterization. Here we present a method to quickly characterize the nanocrystalline grain structure and texture of monolayer WS2 films using scanning nanobeam electron diffraction coupled with multivariate statistical analysis of the resulting data. Our analysis pipeline is highly generalizable and is a useful alternative to...

High-Performance Atomically-Thin Room-Temperature NO2 Sensor

Amin Azizi
Mehmet Dogan
Hu Long
Jeffrey D. Cain
Kyunghoon Lee
Rahmatollah Eskandari
Alessandro Varieschi
Emily C. Glazer
Marvin L. Cohen
Alex Zettl
2020

The development of room-temperature sensing devices for detecting small concentrations of molecular species is imperative for a wide range of low-power sensor applications. We demonstrate a room-temperature, highly sensitive, selective, stable, and reversible chemical sensor based on a monolayer of the transition-metal dichalcogenide Re0.5Nb0.5S2. The sensing device exhibits a thickness-dependent carrier type, and upon exposure to NO2 molecules, its electrical resistance...

Implementation of a canonical phase measurement with quantum feedback

Martin LS
Livingston WP
Hacohen-Gourgy S
Wiseman HM
Siddiqi I
2020

Much of modern metrology and communication technology encodes information in electromagnetic waves, typically as an amplitude or phase. Although current hardware can perform near-ideal measurements of photon number or field amplitude, the ability to perform an ideal phase measurement is still lacking, even in principle. In this work, we implement a single-shot canonical phase measurement on a one-photon wave packet, which surpasses the current standard of heterodyne detection and is optimal for single-shot phase estimation. By applying quantum feedback to a Josephson parametric...

ChemEnv: a fast and robust coordination environment identification tool

Waroquiers D
George J
Horton M
Schen S
Persson K
Rignanes G
Gonze X
Hautier G
2020

Coordination or local environments have been used to describe, analyze and understand crystal structures for more than a century. Here, a new tool called ChemEnv, which can identify coordination environments in a fast and robust manner, is presented. In contrast to previous tools, the assessment of the coordination environments is not biased by small distortions of the crystal structure. Its robust and fast implementation enables the analysis of large databases of structures. The code is available open source within the pymatgen package and the software can also be used through a web...

Visualization of the flat electronic band in twisted bilayer graphene near the magic angle twist

Utama MIB
Koch RJ
Lee K
Leconte N
Li H
Zhao S
Jiang L
Zhu J
Watanabe K
Taniguchi T
Ashby PD
Weber-Bargioni A
Zettl A
Jozwiak C
Jung J
Rotenberg E
Bostwick A
Wang F
2020

Bilayer graphene has been predicted to host a moiré miniband with flat dispersion if the layers are stacked at specific twist angles known as the ’magic angles’1,2. Recently...

Precise Colloidal Plasmonic Photocatalysts Constructed by Multistep Photodepositions

Hyun Dong Ha
Chang Yan
Georgios Katsoukis
Gaurav A. Kamat
Ivan A. Moreno-Hernandez
Heinz Frei
A. Paul Alivisatos
2020

Natural photosynthesis relies on a sophisticated charge transfer pathway among multiple components with precise spatial, energetic, and temporal organizations in the aqueous environment. It continues to inspire and challenge the design and fabrication of artificial multicomponent colloidal nanostructures for solar-to-fuel conversion. Herein, we introduce a plasmonic photocatalyst synthesized with colloidal methods with five integrated components including cocatalysts installed in orthogonal locations. The precise deposition of individual inorganic components on an Au/TiO...

The role of resonant nuclear modes in vibrationally assisted energy transport: The LHCII complex

Bhattacharyya P
Fleming GR
2020

In this paper, we discuss the explicit role of resonant nuclear/vibrational modes in mediating energy transport among chlorophylls in the Light-harvesting Complex II (LHCII), the major light-harvesting complex in green plants. The vibrational modes are considered to be resonant/quasi-resonant with the energy gap between electronic excitons. These resonant vibrations, along with the remaining nuclear degrees of freedom, constitute the environment/bath to the electronically excited system and contribute to two major phenomena: (a) decoherence and (b) incoherent phonon-mediated...

An improved symmetry-based approach to reciprocal space path selection in band structure calculations

Munro JM
Latimer K
Horton MK
Dwaraknath S
Persson KA
2020

Band structures for electrons, phonons, and other quasiparticles are often an important aspect of describing the physical properties of periodic solids. Most commonly, energy bands are computed along a one-dimensional path of high-symmetry points and line segments in reciprocal space (the “k-path”), which are assumed to pass through important features of the dispersion landscape. However, existing methods for choosing this path rely on tabulated lists of high-symmetry points and line segments in the first Brillouin zone, determined using different symmetry...