2022 New's Items

Entanglement of Square Nets in Covalent Organic Frameworks

Jin F
Nguyen HL
Zhong Z
Han X
Zhu C
Pei X
Ma Y
Yaghi OM
2022

Two entangled 2D square covalent organic frameworks (COFs) have been synthesized from 4,4′,4″,4‴-(9,9′-spirobi[fluorene]-2,2′,7,7′-tetrayl)-tetrabenzaldehhyde (SFTB) and p-phenylenediamine (PPA) and benzidine (BZD) to form COF-38, [(SFTB)(PPA)2]imine, and its isoreticular form COF-39, [(SFTB)(BZD)2]imine. We also report the single-crystal electron diffraction structure of COF-39 and find that it is composed of mutually entangled 2D square nets (sql...

Thermal Percolation in Well-Defined Nanocomposite Thin Films

Chang BS
Li C
Dai J
Evans K
Huang J
He M
Hu W
Tian Z
Xu T
2022

Thermal percolation in polymer nanocomposites─the rapid increase in thermal transport due to the formation of networks among fillers─is the subject of great interest in thermal management ranging from general utility in multifunctional nanocomposites to high-conductivity applications such as thermal interface materials. However, It remains a challenging subject encompassing both experimental and modeling hurdles. Successful reports of thermal percolation are exclusively found in high-aspect-ratio, conductive fillers such as graphene, albeit at filler loadings significantly higher...

Multiscale Characterization of the Influence of the Organic–Inorganic Interface on the Dielectric Breakdown of Nanocomposites

Pieters PF
Lainé A
Li H
Lu YH
Singh Y
Wang LW
Liu Y
Xu T
Alivisatos AP
Salmeron M
2022

Nanoscale engineered materials such as nanocomposites can display or be designed to enhance their material properties through control of the internal interfaces. Here, we unveil the nanoscale origin and important characteristics of the enhanced dielectric breakdown capabilities of gold nanoparticle/polymer nanocomposites. Our multiscale approach spans from the study of a single chemically designed organic/inorganic interface to micrometer-thick films. At the nanoscale, we relate the improved breakdown strength to the interfacial charge retention capability by combining scanning probe...

Observation of an Orientational Glass in a Superlattice of Elliptically-Faceted CdSe Nanocrystals

Abbas AS
Vargo E
Jamali V
Ercius P
Pieters PF
Brinn RM
Ben-Moshe A
Cho MG
Xu T
Alivisatos AP
2022

Extensive prior work has shown that colloidal inorganic nanocrystals coated with organic ligand shells can behave as artificial atoms and, as such, form superlattices with different crystal structures and packing densities. Although ordered superlattices present a high degree of long-range positional order, the relative crystallographic orientation of the inorganic nanocrystals with respect to each other tends to be random. Recent works have shown that superlattices can achieve orientational alignment through combinations of nanocrystal faceting and ligand modification, as well as...

Symmetry-Breaking and Self-Sorting in Block Copolymer-Based Multicomponent Nanocomposites

Ma L
Huang H
Ercius P
Alexander-Katz A
Xu T
2022

Co-assembly of inorganic nanoparticles (NPs) and nanostructured polymer matrix represents an intricate interplay of enthalpic or entropic forces. Particle size largely affects the phase behavior of the nanocomposite. Theoretical studies indicate that new morphologies would emerge when the particles become comparable to the soft matrix’s size, but this has rarely been supported experimentally. By designing a multicomponent blend composed of NPs, block copolymer-based supramolecules, and small molecules, a 3-D ordered lattice beyond the native BCP’s morphology was recently reported...

Conductive Ink with Circular Life Cycle for Printed Electronics

Kwon J
DelRe C
Kang P
Hall A
Arnold D
Jayapurna I
Ma L
Michalek M
Ritchie RO
Xu T
2022

Electronic waste carries energetic costs and an environmental burden rivaling that of plastic waste due to the rarity and toxicity of the heavy-metal components. Recyclable conductive composites are introduced for printed circuits formulated with polycaprolactone (PCL), conductive fillers, and enzyme/protectant nanoclusters. Circuits can be printed with flexibility (breaking strain ≈80%) and conductivity (≈2.1 × 104 S m−1). These composites are degraded at the end of life by immersion in warm water with programmable latency....

Using Machine Learning to Predict and Understand Complex Self-Assembly Behaviors of a Multicomponent Nanocomposite

Vargo E
Dahl JC
Evans KM
Khan T
Alivisatos AP
Xu T
2022

Blends of nanoparticles, polymers, and small molecules can self-assemble into optical, magnetic, and electronic devices with structure-dependent properties. However, the relationship between a multicomponent nanocomposite's formulation and its assembled structure is complex and cannot be predicted by theory. The blends can be strongly influenced by processing conditions, which can introduce non-equilibrium states. Currently, nanocomposite devices are designed through cycles of experimental trial and error. Machine learning (ML) methods are a compelling alternative because they can...

Dynamics of photosynthetic light harvesting systems interacting with N-photon Fock states

Ko L
Cook RL
Whaley KB
2022

We develop a method to simulate the excitonic dynamics of realistic photosynthetic light harvesting systems, including non-Markovian coupling to phonon degrees of freedom, under excitation by N-photon Fock state pulses. This method combines the input–output and the hierarchical equations of motion formalisms into a double hierarchy of density matrix equations. We show analytically that under weak field excitation relevant to natural photosynthesis conditions, an N-photon Fock state input and a corresponding coherent state input give rise to equal density matrices in the excited...

Topological quantum interference in a pumped Su-Schrieffer-Heeger lattice

Li Z
Atalaya J
Whaley KB
2022

Topological quantum interference emerges from the interplay between quantum mechanics and topology. We present evidence for two types of such interference phenomenon that can result from the quantum dynamics of initial topological states. We realize both types of topological quantum interference in a pumped non-Hermitian Su-Schrieffer-Heeger lattice that can be implemented by creation and coherent control of excitonic states of trapped neutral atoms. On quenching the system from the topological to the gapless phases and then back again, we find that interference patterns develop in...

Interplay of vibration- and environment-assisted energy transfer

Li Z
Ko L
Yang Z
Sarovar M
Whaley KB
2022

We study the interplay between two environmental influences on excited state energy transfer in photosynthetic light harvesting complexes, namely, vibrationally assisted energy transfer (VAET) and environment-assisted quantum transport (ENAQT), considering a dimeric chromophore donor–acceptor model as a prototype for larger systems. We demonstrate how the basic features of the excitonic energy transfer are influenced by these two environments, both separately and together, with the environment being fully quantum in the case of VAET and treated in the Haken–Strobl–Reineker classical...