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1. High kinetic stability and high density of Ir(ppy)3 doped organic semiconductor glasses

   https://doi.org/10.1063/5.0287781  

   Lee, Yejung; Cheng, Shinian; Yu, Lian; Ediger, M D (September 2025, The Journal of Chemical Physics)

   Glasses prepared by physical vapor deposition (PVD) can have advantageous material properties, such as highly enhanced thermal stability and denser molecular packing, and thin glassy films prepared by PVD are utilized as active layers in organic light emitting diodes (OLEDs). However, the stability and density of PVD glasses with compositions typical of OLED devices are not well studied. Here, we prepared Ir(ppy)3 doped vapor-deposited glasses in three different organic semiconductor hosts; Ir(ppy)3 in a dilute concentration is often used as a light emitter in phosphorescent OLEDs. We studied these glasses during temperature ramping using spectroscopic ellipsometry and found that the Ir(ppy)3 doped PVD glasses have high kinetic stability and high density. Surprisingly, the observed kinetic stability exceeds that of single-component PVD glasses. This work allows further understanding of the material properties influencing OLED performance, thus facilitating the design of durable and stable devices. 

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2. Evidence for Host Selectivity and Specialization by Epizoic Chelonibia Barnacles Between Hawksbill and Green Sea Turtles

   https://doi.org/10.3389/fevo.2021.807237  

   Boyd, Liberty L; Zardus, John D; Knauer, Courtney M; Wood, Lawrence D (December 2021, Frontiers in Ecology and Evolution)

   Epibionts are organisms that utilize the exterior of other organisms as a living substratum. Many affiliate opportunistically with hosts of different species, but others specialize on particular hosts as obligate associates. We investigated a case of apparent host specificity between two barnacles that are epizoites of sea turtles and illuminate some ecological considerations that may shape their host relationships. The barnaclesChelonibia testudinariaandChelonibia caretta, though roughly similar in appearance, are separable by distinctions in morphology, genotype, and lifestyle. However, though each is known to colonize both green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles,C. testudinariais >5 times more common on greens, whileC. carettais >300 times more common on hawksbills. Two competing explanations for this asymmetry in barnacle incidence are either that the species’ larvae are spatially segregated in mutually exclusive host-encounter zones or their distributions overlap and the larvae behaviorally select their hosts from a common pool. We indirectly tested the latter by documenting the occurrence of adults of both barnacle species in two locations (SE Florida and Nose Be, Madagascar) where both turtle species co-mingle. For green and hawksbill turtles in both locations (Florida:n= 32 andn= 275, respectively; Madagascar:n= 32 andn= 125, respectively), we found thatC. testudinariaoccurred on green turtles only (percent occurrence – FL: 38.1%; MD: 6.3%), whereas the barnacleC. carettawas exclusively found on hawksbill turtles (FL: 82.2%; MD: 27.5%). These results support the hypothesis that the larvae of these barnacles differentially select host species from a shared supply. Physio-biochemical differences in host shell material, conspecific chemical cues, external microbial biofilms, and other surface signals may be salient factors in larval selectivity. Alternatively, barnacle presence may vary by host micro-environment. Dissimilarities in scute structure and shell growth between hawksbill and green turtles may promote critical differences in attachment modes observed between these barnacles. In understanding the co-evolution of barnacles and hosts it is key to consider the ecologies of both hosts and epibionts in interpreting associations of chance, choice, and dependence. Further studies are necessary to investigate the population status and settlement spectrum of barnacles inhabiting sea turtles. 

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3. Seeing luminescence appear as crystals crumble. Isolation and subsequent self-association of individual [(C ₆ H ₁₁ NC) ₂ Au] ⁺ ions in crystals

   https://doi.org/10.1039/d0sc03299a  

   Luong, Lucy M.; Lowe, Christopher D.; Adams, Alexandria V.; Moshayedi, Venoos; Olmstead, Marilyn M.; Balch, Alan L. (November 2020, Chemical Science)

   null (Ed.)

   Non-luminescent, isostructural crystals of [(C 6 H 11 NC) 2 Au](EF 6 )·C 6 H 6 (E = As, Sb) lose benzene upon standing in air to produce green luminescent (E = As) or blue luminescent (E = Sb) powders. Previous studies have shown that the two-coordinate cation, [(C 6 H 11 NC) 2 Au] + , self-associates to form luminescent crystals that contain linear or nearly linear chains of cations and display unusual polymorphic, vapochromic, and/or thermochromic properties. Here, we report the formation of non-luminescent crystalline salts in which individual [(C 6 H 11 NC) 2 Au] + ions are isolated from one another. In [(C 6 H 11 NC) 2 Au](BArF 24 ) ((BArF 24 ) − is tetrakis[3,5-bis(trifluoromethyl)phenyl]borate) each cation is surrounded by two anions that prohibit any close approach of the gold ions. Crystallization of [(C 6 H 11 NC) 2 Au](EF 6 ) (E = As or Sb, but not P) from benzene solution produces colorless, non-emissive crystals of the solvates [(C 6 H 11 NC) 2 Au](EF 6 )·C 6 H 6 . These two solvates are isostructural and contain columns in which cations and benzene molecules alternate. With the benzene molecules separating the cations, the shortest distances between gold ions are 6.936(2) Å for E = As and 6.9717(19) Å for E = Sb. Upon removal from the mother liquor, these crystals crack due to the loss of benzene from the crystal and form luminescent powders. Crystals of [(C 6 H 11 NC) 2 Au](SbF 6 )·C 6 H 6 that powder out form a pale yellow powder with a blue luminescence with emission spectra and powder X-ray diffraction data that show that the previously characterized [(C 6 H 11 NC) 2 Au](SbF 6 ) is formed. In the process, the distances between the gold( i ) ions decrease to ∼3 Å and half of the cyclohexyl groups move from an axial orientation to an equatorial one. Remarkably, when crystals of [(C 6 H 11 NC) 2 Au](AsF 6 )·C 6 H 6 stand in air, they lose benzene and are converted into the yellow, green-luminescent polymorph of [(C 6 H 11 NC) 2 Au](AsF 6 ) rather than the colorless, blue-luminescent polymorph. Paradoxically, the yellow, green-luminescent powder that forms as well as authentic crystals of the yellow, green-luminescent polymorph of [(C 6 H 11 NC) 2 Au](AsF 6 ) are sensitive to benzene vapor and are converted by exposure to benzene vapor into the colorless, blue-luminescent polymorph. 

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4. Unique prospects of phase change material Sb ₂ Se ₃ for ultra-compact reconfigurable nanophotonic devices

   https://doi.org/10.1364/OME.435979  

   Jia, Wei; Menon, Rajesh; Sensale-Rodriguez, Berardi (August 2021, Optical Materials Express)

   In this work, we explore inverse designed reconfigurable digital metamaterial structures based on phase change material Sb₂Se₃for efficient and compact integrated nanophotonics. An exemplary design of a 1 × 2 optical switch consisting of a 3 µm x 3 µm pixelated domain is demonstrated. We show that: (i) direct optimization of a domain containing only Si and Sb₂Se₃pixels does not lead to a high extinction ratio between output ports in the amorphous state, which is owed to the small index contrast between Si and Sb₂Se₃in such a state. As a result, (ii) topology optimization, e.g., the addition of air pixels, is required to provide an initial asymmetry that aids the amorphous state's response. Furthermore, (iii) the combination of low loss and high refractive index change in Sb₂Se₃, which is unique among all phase change materials in the telecommunications 1550 nm band, translates into an excellent projected performance; the optimized device structure exhibits a low insertion loss (∼1.5 dB) and high extinction ratio (>18 dB) for both phase states. 

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5. A metal-free all-organic ammonium-ion battery with low-temperature applications

   https://doi.org/10.1039/d2ta08988b  

   Kuchena, Shelton Farai; Wang, Ying (February 2023, Journal of Materials Chemistry A)

   Current commercial batteries are mainly metal based, with metal elements in charge carriers and/or electrode materials, which poses potential economic and environmental concerns due to the heavy use of nonrenewable metals. Thus, metal-free batteries present a unique opportunity as sustainable energy storage devices, though the relevant research is still in its infancy. Herein, we present an all-organic metal-free NH 4 + ion full battery that can operate at a low temperature of 0 °C, by using polypyrrole (PPy) as the cathode, polyaniline (PANI) as the anode, and 19 m ammonium acetate aqueous solution as electrolyte. For the first time, PPy is demonstrated as a high-capacity host material for both NH 4 + and K + storage, when cycled in water in salt electrolytes (WiSEs). When tested in a three-electrode cell containing 25 m NH 4 CH 3 COO electrolyte, PPy exhibits an impressive capacity of 125 mA h g −1 at a specific current of 1 A g −1 and retains 43.61 mA h g −1 at 25 A g −1 . Additionally, a full battery is assembled using the PPy cathode and PANI anode coupled with 19 m NH 4 CH 3 COO WiSE. This battery is found to deliver a capacity of 78.405 mA h g −1 at 25 °C and 49.083 mA h g −1 at 0 °C with a capacity retention of 71.83% after 200 cycles, demonstrating its potential for operations at low temperatures. Additionally, the physiochemical properties of NH 4 + -based WiSEs are examined by Raman and nuclear magnetic resonance (NMR) spectroscopies, to explore their electrochemical behaviors and the fundamental effect of salt concentration on the electrolyte characteristics. This study presents the first non-metal battery with potential for low-temperature applications and opens the door to future metal-free electronics that would generate long-term benefits to the environment. 

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