2020 New's Items

Digital Reticular Chemistry

Lyu H
Ji Z
Wuttke S
Yaghi OM
2020

Reticular chemistry operates in an infinite space of compositions, structures, properties, and applications. Although great progress has been made in exploring this space through the development of metal-organic frameworks and covalent organic frameworks, there remains a gap between what we foresee as being possible and what can actually be accomplished with the current tools and methods. The establishment of digital reticular chemistry, where digital tools are deployed, in particular laboratory robotics and artificial intelligence, will fundamentally change the current workflow to...

Charging-driven coarsening and melting of a colloidal nanoparticle monolayer at an ionic liquid–vacuum interface

Bischak CG
Raybin JG
Kruppe JW
Ginsberg NS
2020

We induce and investigate the coarsening and melting dynamics of an initially static nanoparticle colloidal monolayer at an ionic liquid–vacuum interface, driven by a focused, scanning electron beam. Coarsening occurs through grain interface migration and larger-scale motions such as grain rotations, often facilitated by sliding dislocations. The progressive decrease in area fraction that drives melting of the monolayer is explained using an electrowetting model whereby particles at the interface are solvated once their accumulating charge recruits sufficient counterions to subsume...

Phase Transitions and Anion Exchange in All-Inorganic Halide Perovskites

Steele JA
Lai M
Zhang Y
Lin Z
Hofkens J
Roeffaers MBJ
Yang P
2020

A new generation of semiconducting materials based on metal halide perovskites has recently been launched into the scientific spotlight, exhibiting outstanding optoelectronic properties and providing promise for the development of efficient optical devices. As a vivid example, solar cells made from these materials have quickly reached conversion efficiencies exceeding 25%, now on par with well-established technologies, like silicon. Their widespread success is due, in part, to a unique ability to retain high-quality optoelectronic performance while being easily solution-processed into thin...

Quantum Ratcheted Photophysics in Energy Transport

Bhattacharyya P
Fleming GR
2020

In this paper, we explore the scope of vibrations as quantum ratchets that serve as nonthermal routes to achieving population transport in systems where excitation transport between molecules is otherwise energetically unfavorable. In addition to their role as channels of transport, we investigate the effect of resonance of the vibrations, which are described by Huang–Rhys mixing, with excitonic energy gaps, which leads to strongly mixed vibronic excitons. Finally, we explore the interplay of resonance and Huang–Rhys mixing with electronic coupling between the molecules, in the...

Defect-Accommodating Intermediates Yield Selective Low-Temperature Synthesis of YMnO3 Polymorphs

Todd PK
Wustrow A
McAuliffe RD
McDermott MJ
Tran GT
McBride BC
Boeding ED
O’Nolan D
Lui CH
Dwaraknath SS
Chapman KW
Billinge SJL
Persson KA
Huq A
Veith GM
Neilson JR
2020

In the synthesis of complex oxides, solid-state metathesis provides low-temperature reactions where product selectivity can be achieved through simple changes in precursor composition. The influence of precursor structure, however, is less understood in solid-state synthesis. Here we present the ternary metathesis reaction (LiMnO2 + YOCl → YMnO3 + LiCl) to target two yttrium manganese oxide products, hexagonal and orthorhombic YMnO3, when starting from three different LiMnO2...

Glove-based sensors for multimodal monitoring of natural sweat

Bariya M
Li L
Ghattamaneni R
Ahn CH
Nyein HY
Tai LC
Javey A
2020

Sweat sensors targeting exercise or chemically induced sweat have shown promise for noninvasive health monitoring. Natural thermoregulatory sweat is an attractive alternative as it can be accessed during routine and sedentary activity without impeding user lifestyles and potentially preserves correlations between sweat and blood biomarkers. We present simple glove-based sensors to accumulate natural sweat with minimal evaporation, capitalizing on high sweat gland densities to collect hundreds of microliters in just 30 min without active sweat stimulation. Sensing electrodes are...

Inducing metallicity in graphene nanoribbons via zero-mode superlattices

Rizzo DJ
Veber GC
Jiang J
McCurdy R
Cao T
Bronner C
Chen T
Louie SG
Fischer FR
Crommie MF
2020

The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) are challenging because lateral quantum confinement and many-electron interactions induce electronic band gaps when graphene is patterned at nanometer length scales. Recent developments in bottom-up synthesis have enabled the design and characterization of atomically precise GNRs, but strategies for realizing GNR metallicity have been elusive. Here we demonstrate a general technique for inducing metallicity in GNRs by inserting a symmetric superlattice of zero-energy modes into otherwise...

Structural and electronic switching of a single crystal 2D metal-organic framework prepared by chemical vapor deposition

Claire FJ
Solomos MA
Kim J
Wang G
Siegler MA
Crommie MF
Kempa TJ
2020

The incorporation of metal-organic frameworks into advanced devices remains a desirable goal, but progress is hindered by difficulties in preparing large crystalline metal-organic framework films with suitable electronic performance. We demonstrate the direct growth of large-area, high quality, and phase pure single metal-organic framework crystals through chemical vapor deposition of a dimolybdenum paddlewheel precursor, Mo2(INA)4. These exceptionally uniform, high quality crystals cover areas up to 8600 µm2 and can be grown down to thicknesses of 30...

The ultrafast onset of exciton formation in 2D semiconductors

Chiara Trovatello
Florian Katsch
Nicholas J. Borys
Malte Selig
Kaiyuan Yao
Rocio Borrego-Varillas
Francesco Scotognella
Ilka Kriegel
Aiming Yan
Alex Zettl
P. James Schuck
Andreas Knorr
Giulio Cerullo
Stefano Dal Conte
2020

The equilibrium and non-equilibrium optical properties of single-layer transition metal dichalcogenides (TMDs) are determined by strongly bound excitons. Exciton relaxation dynamics in TMDs have been extensively studied by time-domain optical spectroscopies. However, the formation dynamics of excitons following non-resonant photoexcitation of free electron-hole pairs have been challenging to directly probe because of their inherently fast timescales. Here, we use extremely short optical pulses to non-resonantly excite an electron-hole plasma and show the formation of two-dimensional...

Reproducibility in G0W0 calculations for solids

T. Rangel
M. Del Ben
D. Varsano
G. Antonius
F. Bruneval
F. H. da Jornada
M. J. van Setten
O. K. Orhan
D. D. O'Regan
A. Canning
A. Ferretti
A. Marini
G.-M. Riganese
J. Deslippe
S. G. Louie
J. B. Neaton
2020

Ab initio many-body perturbation theory within the GW approximation is a Green's function formalism widely used in the calculation of quasiparticle excitation energies of solids. In what has become an increasingly standard approach, Kohn–Sham eigenenergies, generated from a DFT calculation with a strategically-chosen exchange–correlation functional “starting point”, are used to construct G and W, and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways to construct the GW self-energy, and these can lead to variations in predicted...