1,328 research outputs found
Interfacial Engineering of Flexible Transparent Conducting Films
One-dimensional (1D) carbon nanotubes (CNTs) and silver nanowires (AgNWs) have been used as replacements for brittle indium tin oxide (ITO) in the fabrication of transparent conducting films (TCFs), which can be used in opto-electronic devices such as screen panels, solar cell panels, and organic light-emitting diodes. This chapter describes a fabrication method of high-performance TCFs by solution processing of single-walled CNTs (SWCNTs) and AgNWs. Highly uniform TCFs with SWCNTs and AgNW inks were fabricated using spray deposition. Their performance was modulated by interfacial engineering such as overcoating with silane compound for densification of SWCNT networks and chemical or photothermal welding of SWCNT networks on thermoplastic substrates. Moreover, the hybridization of SWCNTs, AgNWs, and graphene oxide nanosheets is a promising approach to mitigate their drawbacks via p-type doping, electrical stabilization, or interfacial stabilization on plastic substrates. The rational control of 1D material networks can provide a good opportunity to fabricate high-performance TCFs for flexible opto-electronic devices
Correlated electronic states at domain walls of a Mott-charge-density-wave insulator 1T-TaS2
Domain walls in interacting electronic systems can have distinct localized
states, which often govern physical properties and may lead to unprecedented
functionalities and novel devices. However, electronic states within domain
walls themselves have not been clearly identified and understood for strongly
correlated electron systems. Here, we resolve the electronic states localized
on domain walls in a Mott-charge-density-wave(CDW) insulator 1T-TaS2 using
scanning tunneling spectroscopy. We establish that the domain wall state
decomposes into two nonconducting states located at the center of domain walls
and edges of domains. Theoretical calculations reveal their atomistic origin as
the local reconstruction of domain walls under the strong influence of electron
correlation. Our results introduce a concept for the domain wall electronic
property, the wall's own internal degrees of freedom, which is potentially
related to the controllability of domain wall electronic properties
Zoology of domain walls in quasi-2D correlated charge density wave of 1T-TaS2
Domain walls in correlated charge density wave compounds such as 1T-TaS2 can
have distinct localized states which govern physical properties and
functionalities of emerging quantum phases. However, detailed atomic and
electronic structures of domain walls have largely been elusive. We identify
using scanning tunneling microscope and density functional theory calculations
the atomic and electronic structures for a plethora of discommensuration domain
walls in 1T-TaS2 quenched metastably with nanoscale domain wall networks. The
domain walls exhibit various in-gap states within the Mott gap but metallic
states appear in only particular types of domain walls. A systematic
understanding of the domain-wall electronic property requests not only the
electron counting but also including various intertwined interactions such as
structural relaxation, electron correlation, and charge transfer. This work
guides the domain wall engineering of the functionality in correlated van der
Waals materials.Comment: 7 pages, 4 figure
Mobile Kink Solitons in a Van der Waals Charge-Density-Wave Layer
Kinks, point-like geometrical defects along dislocations, domain walls, and
DNA, are stable and mobile, as solutions of a sine-Gordon wave equation. While
they are widely investigated for crystal deformations and domain wall motions,
electronic properties of individual kinks have received little attention. In
this work, electronically and topologically distinct kinks are discovered along
electronic domain walls in a correlated van der Waals insulator of
1-TaS. Mobile kinks and antikinks are identified as trapped by pinning
defects and imaged in scanning tunneling microscopy. Their atomic structures
and in-gap electronic states are unveiled, which are mapped approximately into
Su-Schrieffer-Heeger solitons. The twelve-fold degeneracy of the domain walls
in the present system guarantees an extraordinarily large number of distinct
kinks and antikinks to emerge. Such large degeneracy together with the robust
geometrical nature may be useful for handling multilevel information in van der
Waals materials architectures.Comment: 12 pages, 4 figure
Grouping-matrix based Graph Pooling with Adaptive Number of Clusters
Graph pooling is a crucial operation for encoding hierarchical structures
within graphs. Most existing graph pooling approaches formulate the problem as
a node clustering task which effectively captures the graph topology.
Conventional methods ask users to specify an appropriate number of clusters as
a hyperparameter, then assume that all input graphs share the same number of
clusters. In inductive settings where the number of clusters can vary, however,
the model should be able to represent this variation in its pooling layers in
order to learn suitable clusters. Thus we propose GMPool, a novel
differentiable graph pooling architecture that automatically determines the
appropriate number of clusters based on the input data. The main intuition
involves a grouping matrix defined as a quadratic form of the pooling operator,
which induces use of binary classification probabilities of pairwise
combinations of nodes. GMPool obtains the pooling operator by first computing
the grouping matrix, then decomposing it. Extensive evaluations on molecular
property prediction tasks demonstrate that our method outperforms conventional
methods.Comment: 10 pages, 3 figure
Geometrically Aligned Transfer Encoder for Inductive Transfer in Regression Tasks
Transfer learning is a crucial technique for handling a small amount of data
that is potentially related to other abundant data. However, most of the
existing methods are focused on classification tasks using images and language
datasets. Therefore, in order to expand the transfer learning scheme to
regression tasks, we propose a novel transfer technique based on differential
geometry, namely the Geometrically Aligned Transfer Encoder (GATE). In this
method, we interpret the latent vectors from the model to exist on a Riemannian
curved manifold. We find a proper diffeomorphism between pairs of tasks to
ensure that every arbitrary point maps to a locally flat coordinate in the
overlapping region, allowing the transfer of knowledge from the source to the
target data. This also serves as an effective regularizer for the model to
behave in extrapolation regions. In this article, we demonstrate that GATE
outperforms conventional methods and exhibits stable behavior in both the
latent space and extrapolation regions for various molecular graph datasets.Comment: 12+11 pages, 6+1 figures, 0+7 table
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