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1. Single Crystal Microwires of p ‐DTS(FBTTh 2 ) 2 and Their Use in the Fabrication of Field‐Effect Transistors and Photodetectors

   https://doi.org/10.1002/adfm.201702073  

   Cui, Qiuhong ; Hu, Yuanyuan ; Zhou, Cheng ; Teng, Feng ; Huang, Jianfei ; Zhugayevych, Andriy ; Tretiak, Sergei ; Nguyen, Thuc‐Quyen ; Bazan, Guillermo C. ( November 2017 , Advanced Functional Materials)

   Single crystal microwires of a well‐studied organic semiconductor used in organic solar cells, namelyp‐DTS(FBTTh₂)₂, are prepared via a self‐assembly method in solution. The high level of intermolecular organization in the single crystals facilitates migration of charges, relative to solution‐processed films, and provides insight into the intrinsic charge transport properties ofp‐DTS(FBTTh₂)₂. Field‐effect transistors based on the microwires can achieve hole mobilities on the order of ≈1.8 cm²V⁻¹s⁻¹. Furthermore, these microwires show photoresponsive electrical characteristics and can act as photoswitches, with switch ratios over 1000. These experimental results are interpreted using theoretical simulations using an atomistic density functional theory approach. Based on the lattice organization, intermolecular couplings and reorganization energies are calculated, and hole mobilities for comparison with experimental measurements are further estimated. These results demonstrate a unique example of the optoelectronic applications ofp‐DTS(FBTTh₂)₂microwires.

    

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2. Pachyrhynchus Weevils Use 3D Photonic Crystals with Varying Degrees of Order to Create Diverse and Brilliant Displays

   https://doi.org/10.1002/smll.202200592  

   Parisotto, Alessandro ; Steiner, Ullrich ; Cabras, Analyn Anzano ; Van Dam, Matthew H. ; Wilts, Bodo D. ( April 2022 , Small)

   The brilliant appearance of Easter Egg weevils, genusPachyrhynchus(Coleoptera, Curculionidae), originates from complex dielectric nanostructures within their elytral scales and elytra. Previous work, investigating singular members of thePachyrhynchusshowed the presence of either quasi‐ordered or ordered 3D photonic crystals based on the single diamond () symmetry in their scales. However, little is known about the diversity of the structural coloration mechanisms within the family. Here, the optical properties withinPachyrhynchusare investigated by systematically identifying their spectral and structural characteristics. Four principal traits that vary their appearance are identified and the evolutionary history of these traits to identify ecological trends are reconstructed. The results indicate that the coloration mechanisms across the Easter Egg weevils are diverse and highly plastic across closely related species with features appearing at multiple independent times across their phylogeny. This work lays a foundation for a better understanding of the various forms of quasi‐ordered and ordered diamond photonic crystal within arthropods.

    

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3. In Situ Electron Microscopy of Poly(ethylene glycol) Crystals Grown in Thin Ionic Liquids Films

   https://doi.org/10.1002/pol.20190120  

   Srivastava, Satyam ; Ribbe, Alexander E. ; Russell, Thomas P. ; Hoagland, David A. ( January 2020 , Journal of Polymer Science)

   Crystals of poly(ethylene glycol) grown in thin films of the room temperature ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium ethyl sulfate were examined by electron microscopy as a first step toward exploiting nonvolatile liquids for nanoscale imaging of solvated/dissolved polymeric materials. The crystals were generated by cooling supported (over surfaces of varied polarity) and freestanding solution films to room temperature. This “open,” that is, without liquid cell, microscopy was performed on unstained, as‐grown crystals in the presence of the IL. A variety of nearly two‐dimensional crystal morphologies were observed, including rods, fibers, spherulites, compact faceted single crystals, and interconnected networks, with characteristic sizes ranging from tens of nanometers to tens of microns. Electron diffraction patterns for the rods and fibers revealed single crystal‐like long‐range order. The nature of the IL support little affected the morphology, but film thickness and cooling rate proved important. To assess the role of solvent polarity, crystals were also grown from 1‐ethyl‐3‐methylimidazolium ethyl sulfate mixed with the second IL, the less polar ethyl‐tributyl‐phosphonium diethyl phosphate; here, although the morphologies were similar to those made with pure IL, fibrillar morphologies were more prevalent. © 2020 Wiley Periodicals, Inc. J. Polym. Sci.2020,58, 478–486

    

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4. Isoelectronic perturbations to f - d -electron hybridization and the enhancement of hidden order in URu 2 Si 2

   https://doi.org/10.1073/pnas.2026591118  

   Wolowiec, Christian T. ; Kanchanavatee, Noravee ; Huang, Kevin ; Ran, Sheng ; Breindel, Alexander J. ; Pouse, Naveen ; Sasmal, Kalyan ; Baumbach, Ryan E. ; Chappell, Greta ; Riseborough, Peter S. ; et al ( May 2021 , Proceedings of the National Academy of Sciences)

   Electrical resistivity measurements were performed on single crystals of URu_2–xOs_xSi₂up tox= 0.28 under hydrostatic pressure up toP= 2 GPa. As the Os concentration,x, is increased, 1) the lattice expands, creating an effective negative chemical pressureP_ch(x); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressureP_cis required to induce the HO→LMAFM phase transition. We compare the behavior of theT(x,P) phase boundary reported here for the URu_2-xOs_xSi₂system with previous reports of enhanced HO in URu₂Si₂upon tuning withPor similarly in URu_2–xFe_xSi₂upon tuning with positiveP_ch(x). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URu₂Si₂. We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5f-electron and transition metald-electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URu₂Si₂. Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5f-electron states and thed-electron states of Ru and its isoelectronic Fe and Os substituents in URu₂Si₂.

    

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5. Structure and Oxidation States of Giant Unit Cell Compound Dy 117+x Fe 57–y Sn 112–z

   https://doi.org/10.1002/zaac.201700321  

   Brown, Alexander T. ; Barron, Keaton G. ; Salazar, Bryan G. ; Kirby, Parker ; McCandless, Gregory T. ; Walker, Amy V. ; Chan, Julia Y. ( November 2017 , Zeitschrift für anorganische und allgemeine Chemie)

   Motivated by the complex structure and properties of giant unit cell intermetallic compounds, a new isostructural Fe analogue of the Dy₁₁₇Co₅₇Sn₁₁₂structure type was synthesized. Single crystals of Dy₁₂₂Fe₅₅Sn₁₀₁were grown at 1260 °C via a Dy–Fe eutectoid flux. The Fe analogue also adopts the space groupFm3mwith lattice parametersa= 29.914(9) Å,V= 26769(23) ų, andZ= 4. Dy₁₂₂Fe₅₅Sn₁₀₁has a large cell volume, structural complexity, and consists of seven Dy, eight Fe, and ten Sn unique crystallographic sites. There are fifteen fully occupied atomic positions, three unique pairs of alternating atomic positions with positional disorder, and seven partially occupied atomic sites. Within this complex unit cell, only approximately half the unique atomic positions are fully occupied with the remainder of the atoms either positionally or occupationally disordered. X‐ray photoelectron spectroscopy indicates that the compound contains Dy³⁺, Fe⁰, Fe²⁺, Sn⁰, and Sn⁴⁺.

    

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