Now showing items 1-20 of 3208

    • Selectivity descriptors for the direct hydrogenation of CO2 to hydrocarbons during zeolite-mediated bifunctional catalysis

      Galilea, Adrian; Gong, Xuan; Caglayan, Mustafa; Nastase, Stefan-Adrian F.; Abou-Hamad, Edy; Gevers, Lieven; Cavallo, Luigi; Chowdhury, Abhishek Dutta; Gascon, Jorge (Nature Communications, Springer Science and Business Media LLC, 2021-10-08) [Article]
      AbstractCascade processes are gaining momentum in heterogeneous catalysis. The combination of several catalytic solids within one reactor has shown great promise for the one-step valorization of C1-feedstocks. The combination of metal-based catalysts and zeolites in the gas phase hydrogenation of CO2 leads to a large degree of product selectivity control, defined mainly by zeolites. However, a great deal of mechanistic understanding remains unclear: metal-based catalysts usually lead to complex product compositions that may result in unexpected zeolite reactivity. Here we present an in-depth multivariate analysis of the chemistry involved in eight different zeolite topologies when combined with a highly active Fe-based catalyst in the hydrogenation of CO2 to olefins, aromatics, and paraffins. Solid-state NMR spectroscopy and computational analysis demonstrate that the hybrid nature of the active zeolite catalyst and its preferred CO2-derived reaction intermediates (CO/ester/ketone/hydrocarbons, i.e., inorganic-organic supramolecular reactive centers), along with 10 MR-zeolite topology, act as descriptors governing the ultimate product selectivity.
    • Alternating Copolymerization of Epoxides with Isothiocyanates

      Chen, Chao; Gnanou, Yves; Feng, Xiaoshuang (Macromolecules, American Chemical Society (ACS), 2021-10-08) [Article]
      The ring-opening copolymerization of epoxides with isothiocyanates (ITCs) is explored for the first time. In the presence of phosphazenium benzoxide, epoxides investigated in this work including propylene oxide, ethylene oxide, and cyclohexene oxide were successfully copolymerized with both an aromatic ITC, phenyl isothiocyanate, and two aliphatic ITCs, ethyl isothiocyanate and hexyl isothiocyanate. Effects of the phosphazene bases used, of the temperature, and of the presence of Lewis acids, triethyl borane and diethyl zinc (ZnEt2), on the alternating copolymerization were investigated respectively. The thermal properties of the obtained copolymers were analyzed by differential scanning calorimetry and thermogravimetric analysis. The present work reports new ITC heteroallene monomers being alternating copolymerized with epoxides.
    • Chemical Design Rules for Non-Fullerene Acceptors in Organic Solar Cells

      Markina, Anastasia; Lin, Kun-Han; Liu, Wenlan; Poelking, Carl; Firdaus, Yuliar; Villalva, Diego Rosas; Khan, Jafar Iqbal; Paleti, Sri Harish Kumar; Harrison, George T.; Gorenflot, Julien; Zhang, Weimin; De Wolf, Stefaan; McCulloch, Iain; Anthopoulos, Thomas D.; Baran, Derya; Laquai, Frédéric; Andrienko, Denis (Advanced Energy Materials, Wiley, 2021-10-08) [Article]
      Efficiencies of organic solar cells have practically doubled since the development of non-fullerene acceptors (NFAs). However, generic chemical design rules for donor-NFA combinations are still needed. Such rules are proposed by analyzing inhomogeneous electrostatic fields at the donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and molecular alignment parallel to the interface, results in energy level bending that destabilizes the charge transfer state, thus promoting its dissociation into free charges. By analyzing a series of PCE10:NFA solar cells, with NFAs including Y6, IEICO, and ITIC, as well as their halogenated derivatives, it is suggested that the molecular quadrupole moment of ≈75 Debye Å balances the losses in the open circuit voltage and gains in charge generation efficiency.
    • Electrolyte-gated transistors for enhanced performance bioelectronics

      Torricelli, Fabrizio; Adrahtas, Demetra Z.; Bao, Zhenan; Berggren, Magnus; Biscarini, Fabio; Bonfiglio, Annalisa; Bortolotti, Carlo A.; Frisbie, C. Daniel; Macchia, Eleonora; Malliaras, George G.; McCulloch, Iain; Moser, Maximilian; Nguyen, Thuc-Quyen; Owens, Róisín M.; Salleo, Alberto; Spanu, Andrea; Torsi, Luisa (Nature Reviews Methods Primers, Springer Science and Business Media LLC, 2021-10-07) [Article]
      Electrolyte-gated transistors (EGTs), capable of transducing biological and biochemical inputs into amplified electronic signals and stably operating in aqueous environments, have emerged as fundamental building blocks in bioelectronics. In this Primer, the different EGT architectures are described with the fundamental mechanisms underpinning their functional operation, providing insight into key experiments including necessary data analysis and validation. Several organic and inorganic materials used in the EGT structures and the different fabrication approaches for an optimal experimental design are presented and compared. The functional bio-layers and/or biosystems integrated into or interfaced to EGTs, including self-organization and self-assembly strategies, are reviewed. Relevant and promising applications are discussed, including two-dimensional and three-dimensional cell monitoring, ultra-sensitive biosensors, electrophysiology, synaptic and neuromorphic bio-interfaces, prosthetics and robotics. Advantages, limitations and possible optimizations are also surveyed. Finally, current issues and future directions for further developments and applications are discussed.
    • Unraveling the Unconventional Order of a High-Mobility Indacenodithiophene–Benzothiadiazole Copolymer

      Cendra, Camila; Balhorn, Luke; Zhang, Weimin; O’Hara, Kathryn; Bruening, Karsten; Tassone, Christopher J.; Steinrück, Hans-Georg; Liang, Mengning; Toney, Michael F.; McCulloch, Iain; Chabinyc, Michael L; Salleo, Alberto; Takacs, Christopher J. (ACS Macro Letters, American Chemical Society (ACS), 2021-10-05) [Article]
      A new class of donor–acceptor (D–A) copolymers found to produce high charge carrier mobilities competitive with amorphous silicon (>1 cm2 V–1 s–1) exhibit the puzzling microstructure of substantial local order, however lacking long-range order and crystallinity previously deemed necessary for achieving high mobility. Here, we demonstrate the application of low-dose transmission electron microscopy to image and quantify the nanoscale and mesoscale organization of an archetypal D–A copolymer across areas comparable to electronic devices (≈9 μm2). The local structure is spatially resolved by mapping the backbone (001) spacing reflection, revealing nanocrystallites of aligned polymer chains throughout nearly the entire film. Analysis of the nanoscale structure of its ordered domains suggests significant short- and medium-range order and preferential grain boundary orientations. Moreover, we provide insights into the rich, interconnected mesoscale organization of this new family of D–A copolymers by analysis of the local orientational spatial autocorrelations.
    • Understanding Halide Counterion Effects in Enantioselective Ruthenium-Catalyzed Carbonyl (α-Aryl)allylation: Alkynes as Latent Allenes and Trifluoroethanol-Enhanced Turnover in The Conversion of Ethanol to Higher Alcohols via Hydrogen Auto-transfer

      Ortiz, Eliezer; Shezaf, Jonathan Z.; Chang, Yu-Hsiang; Goncalves, Theo; Huang, Kuo-Wei; Krische, Michael J. (Journal of the American Chemical Society, American Chemical Society (ACS), 2021-10-04) [Article]
      Crystallographic characterization of RuX(CO)(η3-C3H5)(JOSIPHOS), where X = Cl, Br, or I, reveals a halide-dependent diastereomeric preference that defines metal-centered stereogenicity and, therefrom, the enantioselectivity of C-C coupling in ruthenium-catalyzed anti-diastereo- and enantioselective C-C couplings of primary alcohols with 1-aryl-1-propynes to form products of carbonyl anti-(α-aryl)allylation. Computational studies reveal that a non-classical hydrogen bond between iodide and the aldehyde formyl CH bond stabilizes the favored transition state for carbonyl addition. An improved catalytic system enabling previously unattainable transformations was developed that employs an iodide-containing precatalyst, RuI(CO)3(η3-C3H5), in combination with trifluoroethanol, as illustrated by the first enantioselective ruthenium-catalyzed C-C couplings of ethanol to form higher alcohols.
    • Boron-Catalyzed Polymerization of Phenyl-Substituted Allylic Arsonium Ylides toward Nonconjugated Emissive Materials from C3/C1 Monomeric Units

      Liu, Pibo; Hadjichristidis, Nikos (ACS Macro Letters, American Chemical Society (ACS), 2021-10-04) [Article]
      Two novel allylic arsonium ylide monomers with a phenyl (steric and electronic effect) group at different positions were synthesized and used in boron-catalyzed polymerization to produce a series of well-defined polymers, poly(2-phenyl-propenylene-co-2-phenyl-propenylidene) (P2-PhAY) and poly(3-phenyl-propenylene-co-3-phenyl-propenylidene) (P3-PhAY), with unusual structures but a controllable molecular weight and relatively low polydispersity. The backbone of these polymers consists of a mixture of C1 (chain grows by one carbon atom at a time) and C3 (chain grows by three carbon atoms at a time) monomeric units, as determined by 1H, 13C, and 1H–13C HSQC 2D NMR. Based on the experimental results and density functional theoretical (DFT) calculations, we were able to propose a mechanism that takes into account not only the steric hindrance, but also the electron effect of the phenyl group. In addition, a nontraditional intrinsic luminescence was observed from the nonconjugated P2-PhAY and P3-PhAY; such unexpected emission is attributed to the formation of C3-unit clusters, as evidenced by ultraviolet–visible and fluorescence spectroscopy.
    • Advances and Challenges in Tin Halide Perovskite Nanocrystals

      Chen, Jia-Kai; Zhang, Bin-Bin; Liu, Qi; Shirahata, Naoto; Mohammed, Omar F.; Bakr, Osman; Sun, Hong-Tao (ACS Materials Letters, American Chemical Society (ACS), 2021-10-01) [Article]
      A major application limit for lead halide perovskite nanocrystals (NCs) is the presence of the highly toxic lead element, raising critical concerns of environmental pollution and health problems. To address this issue, tin halide perovskite NCs have been pushed to the forefront of perovskite research owing to their eco-friendly merit and tantalizing photophysical properties. In this Review, we critically summarize and assess the latest advances in the synthesis approaches of tin halide perovskite NCs including the hot injection, ligand-assisted reprecipitation, and chemical vapor deposition. More specifically, we detail the state-of-the-art preliminary studies in modulating their photophysical properties and in enhancing the stability with a variety of strategies such as precursor engineering, ligand engineering, and alloyed structure construction. Finally, we highlight the remaining challenges that need to be overcome to attain tin halide perovskite NCs with clear structure–property relationships and comparable physical and chemical properties to their lead-based cousins.
    • A molecular design approach towards elastic and multifunctional polymer electronics

      Zheng, Yu; Yu, Zhiao; Zhang, Song; Kong, Xian; Michaels, Wesley; Wang, Weichen; Chen, Gan; Liu, Deyu; Lai, Jian-Cheng; Prine, Nathaniel; Zhang, Weimin; Nikzad, Shayla; Cooper, Christopher B.; Zhong, Donglai; Mun, Jaewan; Zhang, Zhitao; Kang, Jiheong; Tok, Jeffrey B.-H.; McCulloch, Iain; Qin, Jian; Gu, Xiaodan; Bao, Zhenan (Nature Communications, Springer Science and Business Media LLC, 2021-09-29) [Article]
      Next-generation wearable electronics require enhanced mechanical robustness and device complexity. Besides previously reported softness and stretchability, desired merits for practical use include elasticity, solvent resistance, facile patternability and high charge carrier mobility. Here, we show a molecular design concept that simultaneously achieves all these targeted properties in both polymeric semiconductors and dielectrics, without compromising electrical performance. This is enabled by covalently-embedded in-situ rubber matrix (iRUM) formation through good mixing of iRUM precursors with polymer electronic materials, and finely-controlled composite film morphology built on azide crosslinking chemistry which leverages different reactivities with C–H and C=C bonds. The high covalent crosslinking density results in both superior elasticity and solvent resistance. When applied in stretchable transistors, the iRUM-semiconductor film retained its mobility after stretching to 100% strain, and exhibited record-high mobility retention of 1 cm2 V−1 s−1 after 1000 stretching-releasing cycles at 50% strain. The cycling life was stably extended to 5000 cycles, five times longer than all reported semiconductors. Furthermore, we fabricated elastic transistors via consecutively photo-patterning of the dielectric and semiconducting layers, demonstrating the potential of solution-processed multilayer device manufacturing. The iRUM represents a molecule-level design approach towards robust skin-inspired electronics.
    • One-Pot Chemoenzymatic Conversion of Alkynes to Chiral Amines

      Mathew, Sam; Sagadevan, Arunachalam; Renn, Dominik; Rueping, Magnus (ACS Catalysis, American Chemical Society (ACS), 2021-09-29) [Article]
      A one-pot chemoenzymatic sequential cascade for the synthesis of chiral amines from alkynes was developed. In this integrated approach, just ppm amounts of gold catalysts enabled the conversion of alkynes to ketones (>99%) after which a transaminase was used to catalyze the production of biologically valuable chiral amines in a good yield (up to 99%) and enantiomeric excess (>99%). A preparative scale synthesis of (S)-methylbenzylamine and (S)-4-methoxy-methylbenzylamine from its alkyne form gave a yield of 59 and 92%, respectively, with ee > 99%.
    • Single-Particle Spectroscopy as a Versatile Tool to Explore Lower-Dimensional Structures of Inorganic Perovskites

      Bose, Riya; Zhou, Xiaohe; Guo, Tianle; Yang, Haoze; Yin, Jun; Mishra, Aditya; Slinker, Jason D.; Bakr, Osman; Mohammed, Omar F.; Malko, Anton V. (ACS Energy Letters, American Chemical Society (ACS), 2021-09-27) [Article]
      The remarkable defect-tolerant nature of inorganic cesium halide perovskites, leading to near unity photoluminescence (PL) quantum yield and narrow emission line width across the entire visible spectrum, has provided a tantalizing platform for the development of a plethora of light-emitting applications. Recently, lower-dimensional (2D, 1D, and 0D) perovskites have attracted further attention due to their enhanced thermal, photo, and chemical stability as compared to their three-dimensional (3D) analogues. The combination of external size quantization and internal octahedral organization provides a unique opportunity to study and harness “multi-dimensional” electronic properties engineered on both atomic scale and nanoscale. However, crucial research to understand the elementary charge carrier dynamics in lower-dimensional perovskites lags far behind the enormous effort to incorporate them into optoelectronic devices. In this Perspective, we provide a review of recent developments that focus on studies of the dynamics of excitonic complexes in Cs-based perovskite nanocrystals using single-particle time-resolved PL spectroscopy and photon correlation measurements. Single-photon statistical studies not only offer an unprecedented level of detail to directly assess various recombination pathways, but also provide insights into specifics of the charge carriers' localization. We discuss the underlying physicochemical processes that govern PL emission and draw attention to a number of attributes within this class of the materials, especially lower-dimensional perovskites, that may indicate the common origin of the PL emission as well as provide a route map for the vast unexplored territories where single-particle spectroscopy can be a powerful tool to unravel crucial information.
    • Phosphatidylcholine-mediated regulation of growth kinetics for colloidal synthesis of cesium tin halide nanocrystals

      Wang, Lu-Ming; Chen, Jia-Kai; Zhang, Bin-Bin; Liu, Qi; Zhou, Yang; Shu, Jie; Wang, Zuoshan; Shirahata, Naoto; Song, Bo; Mohammed, Omar F.; Bakr, Osman; Sun, Hong-Tao (Nanoscale, Royal Society of Chemistry (RSC), 2021-09-27) [Article]
      Cesium tin halide (CsSnX3, where X is halogen) perovskite nanocrystals (NCs) are one of the most representative alternatives to their lead-based cousins. However, a fundamental understanding of how to regulate the growth kinetics of colloidal CsSnX3 NCs is still lacking and, specifically, the role of surfactants in affecting their growth kinetics remains incompletely understood. Here we report a general approach for colloidal synthesis of CsSnX3 perovskite NCs through a judicious combination of capping agents. We demonstrate that introducing a small amount of zwitterionic phosphatidylcholine in the reaction is of vital importance for regulating the growth kinetics of CsSnX3 NCs, which otherwise merely leads to the formation of large-sized powders. Based on a range of experimental characterization, we propose that the formation of intermediate complexes between zwitterionic phosphatidylcholine and the precursors and the steric hindrance effect of branched fatty acid side-chains of phosphatidylcholine can regulate the growth kinetics of CsSnX3, which enables us to obtain CsSnX3 NCs with emission quantum yields among the highest values ever reported. Our finding of using zwitterionic capping agents to regulate the growth kinetics may inspire more research on the synthesis of high-quality tin-based perovskite NCs that could speed up their practical applications in optoelectronic devices.
    • Spin–Orbit Charge-Transfer Intersystem Crossing of Compact Naphthalenediimide-Carbazole Electron-Donor–Acceptor Triads

      Hussain, Mushraf; El-Zohry, Ahmed; Hou, Yuqi; Toffoletti, Antonio; Zhao, Jianzhang; Barbon, Antonio; Mohammed, Omar F. (The Journal of Physical Chemistry B, American Chemical Society (ACS), 2021-09-20) [Article]
      Compact electron donor-acceptor triads based on carbazole (Cz) and naphthalenediimide (NDI) were prepared to study the spin-orbit charge-transfer intersystem crossing (SOCT-ISC). By variation of the molecular conformation and electron-donating ability of the carbazole moieties, the electronic coupling between the two units was tuned, and as a result charge-transfer (CT) absorption bands with different magnitudes were observed (ε = 4000-18 000 M<sup>-1</sup> cm<sup>-1</sup>). Interestingly, the triads with NDI attached at the 3-C position or with a phenyl spacer at the <i>N</i> position of the Cz moiety, thermally activated delayed fluorescence (TADF) was observed. Femtosecond transient absorption (fs-TA) spectroscopy indicated fast electron transfer (0.8-1.5 ps) from the Cz to NDI unit, followed by population of the triplet state (150-600 ps). Long-lived triplet states (up to τ<sub>T</sub> = 45-50 μs) were observed for the triads. The solvent-polarity-dependent singlet-oxygen quantum yield (Φ<sub>Δ</sub>) is 0-26%. Time-resolved electron paramagnetic resonance (TREPR) spectral study of TADF molecules indicated the presence of the <sup>3</sup>CT state for <b>NDI-Cz-Ph</b> (zero-field-splitting parameter <i>D</i> = 21 G) and an <sup>3</sup>LE state for <b>NDI-Ph-Cz</b> (<i>D</i> = 586 G). The triads were used as triplet photosensitizers in triplet-triplet annihilation upconversion by excitation into the CT absorption band; the upconversion quantum yield was Φ<sub>UC</sub> = 8.2%, and there was a large anti-Stokes shift of 0.55 eV. Spatially confined photoexcitation is achieved with the upconversion using focusing laser beam excitation, and not the normally used collimated laser beam, i.e., the upconversion was only observed at the focal point of the laser beam. Photo-driven intermolecular electron transfer was demonstrated with reversible formation of the NDI<sup>-•</sup> radical anion in the presence of the sacrificial electron donor triethanolamine.
    • Crystallization and Morphology of Triple Crystalline Polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone) PE-b-PEO-b-PCL Triblock Terpolymers

      Matxinandiarena, Eider; Múgica, Agurtzane; Zubitur, Manuela; Ladelta, Viko; Zapsas, Georgios; Cavallo, Dario; Hadjichristidis, Nikos; Müller, Alejandro J. (Polymers, MDPI AG, 2021-09-16) [Article]
      The morphology and crystallization behavior of two triblock terpolymers of polymethylene, equivalent to polyethylene (PE), poly (ethylene oxide) (PEO), and poly (ε-caprolactone) (PCL) are studied: PE227.1-b-PEO4615.1-b-PCL3210.4 (T1) and PE379.5-b-PEO348.8-b-PCL297.6 (T2) (superscripts give number average molecular weights in kg/mol and subscripts composition in wt %). The three blocks are potentially crystallizable, and the triple crystalline nature of the samples is investigated. Polyhomologation (C1 polymerization), ring-opening polymerization, and catalyst-switch strategies were combined to synthesize the triblock terpolymers. In addition, the corresponding PE-b-PEO diblock copolymers and PE homopolymers were also analyzed. The crystallization sequence of the blocks was determined via three independent but complementary techniques: differential scanning calorimetry (DSC), in situ SAXS/WAXS (small angle X-ray scattering/wide angle X-ray scattering), and polarized light optical microscopy (PLOM). The two terpolymers (T1 and T2) are weakly phase segregated in the melt according to SAXS. DSC and WAXS results demonstrate that in both triblock terpolymers the crystallization process starts with the PE block, continues with the PCL block, and ends with the PEO block. Hence triple crystalline materials are obtained. The crystallization of the PCL and the PEO block is coincident (i.e., it overlaps); however, WAXS and PLOM experiments can identify both transitions. In addition, PLOM shows a spherulitic morphology for the PE homopolymer and the T1 precursor diblock copolymer, while the other systems appear as non-spherulitic or microspherulitic at the last stage of the crystallization process. The complicated crystallization of tricrystalline triblock terpolymers can only be fully grasped when DSC, WAXS, and PLOM experiments are combined. This knowledge is fundamental to tailor the properties of these complex but fascinating materials.
    • Recent Progress on Polymers of Intrinsic Microporosity and Thermally Modified Analogue Materials for Membrane-Based Fluid Separations

      Wang, Yingge; Ghanem, Bader; Ali, Zain; Hazazi, Khalid; Han, Yu; Pinnau, Ingo (Small Structures, Wiley, 2021-09-14) [Article]
      Solution-processable amorphous glassy polymers of intrinsic microporosity (PIMs) are promising microporous organic materials for membrane-based gas and liquid separations due to their high surface area and internal free volume, thermal and chemical stability, and excellent separation performance. This review provides an overview of the most recent developments in the design and transport properties of novel ladder PIM materials, polyimides of intrinsic microporosity (PIM–PIs), functionalized PIMs and PIM–PIs, PIM-derived thermally rearranged (TR), and carbon molecular sieve (CMS) membrane materials as well as PIM-based thin film composite membranes for a wide range of energy-intensive gas and liquid separations. In less than two decades, PIMs have significantly lifted the performance upper bounds in H2/N2, H2/CH4, O2/N2, CO2/N2, and CO2/CH4 separations. However, PIMs are still limited by their insufficient gas-pair selectivity to be considered as promising materials for challenging industrial separations such as olefin/paraffin separations. An optimum pore size distribution is required to further improve the selectivity of a PIM for a given application. Specific attention is given to the potential use of PIM-based CMS membranes for energy-intensive CO2/CH4, N2/CH4, C2H4/C2H6, and C3H6/C3H8 separations, and thin film composite membranes containing PIM motifs for liquid separations.
    • Research data supporting "High-mobility, trap-free charge transport in conjugated polymer diodes"

      Nikolka, Mark; Broch, Katharina; Armitage, John; Hanifi, David; Nowack, Peer J.; Venkateshvaran, Deepak; Sadhanala, Aditya; Saska, Jan; Mascal, Mark; Jung, Seok-Heon; Lee, Jin-Kyun; McCulloch, Iain; Salleo, Alberto; Sirringhaus, Henning (Apollo - University of Cambridge Repository, 2021-09-14) [Dataset]
      Origin project including all source data used for Figures 1 to 5.The Project is structured in sub-folders, with one folder dedicated to a specfic Figure of the paper. Folder 1 includes SCLC diode characteristics measured for DPP-BTz SCLC diodes with and without additives. Folder 2 includes low-temperature measurements of diodes, extracted activation energies as well as dn/DE values extracted by SCLC-spectroscopy. Folder 3 includes measured diode characteristics of IDT-BT, MEH:PPV and DPP-DTT SCLC diodes, corresponding dn/dE values and PDS spectroscopy data for these materials. The last Folder includes stability measuremtns of DPP-BTz diodes showing the evolution over 10k IV-characteristics. Any additional data from the paper (such as thoese shown in the SI or GIWAXs data) is available on request. Format
    • An Aqueous Mg 2+ -Based Dual-Ion Battery with High Power Density

      Zhu, Yunpei; Yin, Jun; Emwas, Abdul-Hamid; Mohammed, Omar F.; Alshareef, Husam N. (Advanced Functional Materials, Wiley, 2021-09-13) [Article]
      Rechargeable Mg batteries promise low-cost, safe, and high-energy alternatives to Li-ion batteries. However, the high polarization strength of Mg2+ leads to its strong interaction with electrode materials and electrolyte molecules, resulting in sluggish Mg2+ dissociation and diffusion as well as insufficient power density and cycling stability. Here an aqueous Mg2+-based dual-ion battery is reported to bypass the penalties of slow dissociation and solid-state diffusion. This battery chemistry utilizes fast redox reactions on the polymer electrodes, i.e., anion (de)doping on the polyaniline (PANI) cathode and (de)enolization upon incorporating Mg2+ on the polyimide anode. The kinetically favored and stable electrodes depend on designing a saturated aqueous electrolyte of 4.5 m Mg(NO3)2. The concentrated electrolyte suppresses the irreversible deprotonation reaction of the PANI cathode to enable excellent stability (a lifespan of over 10 000 cycles) and rate performance (33% capacity retention at 500 C) and avoids the anodic parasitic reaction of nitrate reduction to deliver the stable polyimide anode (86.2% capacity retention after 6000 cycles). The resultant full Mg2+-based dual-ion battery shows a high specific power of 10 826 W kg−1, competitive with electrochemical supercapacitors. The electrolyte and electrode chemistries elucidated in this study provide an alternative approach to developing better-performing Mg-based batteries.
    • Design of experiment optimization of aligned polymer thermoelectrics doped by ion-exchange

      Huang, Yuxuan; Lukito Tjhe, Dionisius Hardjo; Jacobs, Ian; Jiao, Xuechen; He, Qiao; Statz, Martin; Ren, Xinglong; Huang, Xinyi; McCulloch, Iain; Heeney, Martin; McNeill, Christopher R.; Sirringhaus, Henning (Applied Physics Letters, AIP Publishing, 2021-09-13) [Article]
      Organic thermoelectrics offer the potential to deliver flexible, low-cost devices that can directly convert heat to electricity. Previous studies have reported high conductivity and thermoelectric power factor in the conjugated polymer poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT). Here, we investigate the thermoelectric properties of PBTTT films in which the polymer chains were aligned uniaxially by mechanical rubbing, and the films were doped by a recently developed ion exchange technique that provides a choice over the counterions incorporated into the film, allowing for more optimized morphology and better stability than conventional charge transfer doping. To optimize the polymer alignment process, we took advantage of two Design of Experiment (DOE) techniques: regular two-level factorial design and central composite design. Rubbing temperature Trub and post-alignment annealing temperature Tanneal were the two factors that were most strongly correlated with conductivity. We were able to achieve high polymer alignment with a dichroic ratio >15 and high electrical conductivities of up to 4345 S/cm for transport parallel to the polymer chains, demonstrating that the ion exchange method can achieve conductivities comparable/higher than conventional charge transfer doping. While the conductivity of aligned films increased by a factor of 4 compared to unaligned films, the Seebeck coefficient (S) remained nearly unchanged. The combination of DOE methodology, high-temperature rubbing, and ion exchange doping provides a systematic, controllable strategy to tune structure–thermoelectric property relationships in semiconducting polymers
    • Local sensorimotor control and learning in robotics with organic neuromorphic electronics

      Krauhausen, Imke; Gkoupidenis, Paschalis; Melianas, Armantas; Keene, Scott T.; Lieberth, Katharina; Ledanseur, Hadrien; Sheelamanthula, Rajendar; Koutsouras, Dimitrios; Torricelli, Fabrizio; McCulloch, Iain; Blom, Paul W. M.; Salleo, Alberto; van de Burgt, Yoeri; Giovannitti , Alexander (Fundació Scito, 2021-09-13) [Conference Paper]
      Artificial intelligence applications have demonstrated their enormous potential for complex processing over the last decade, however they still lack the efficiency and computing capacity of the brain. In living organisms, data signals are represented by sensory and motor processes that are distributed, locally merged and capable of forming dynamic sensorimotor associations through volatile and non-volatile connections. Using similar computational primitives, neuromorphic circuits offer a new way of intelligent information processing that makes it possible to adaptively oberserve, anaylze, operate and interact in real-world scenarios [1-6]. In this work we present a small-scale, locally-trained organic neuromorphic circuit for sensorimotor control and learning, on a robot navigating inside a maze. By connecting the neuromorphic circuit directly to environmental stimuli through sensor signals, the robot is able to respond adaptively to sensory cues and consequently forms a behavioral association to follow the way to the exit. The on-chip sensorimotor integration with low-voltage organic neuromorphic electronics opens the way towards stand-alone, brain-inspired circuitry in autonomous and intelligent robotics.
    • Interfacial Model Deciphering High-Voltage Electrolytes for High Energy Density, High Safety, and Fast-Charging Lithium-Ion Batteries

      Zou, Yeguo; Cao, Zhen; Zhang, Junli; Wahyudi, Wandi; Wu, Yingqiang; Liu, Gang; Li, Qian; Cheng, Haoran; Zhang, Dongyu; Park, Geon-Tae; Cavallo, Luigi; Anthopoulos, Thomas D.; Wang, Limin; Sun, Yang-Kook; Ming, Jun (Advanced Materials, Wiley, 2021-09-12) [Article]
      High-voltage lithium-ion batteries (LIBs) enabled by high-voltage electrolytes can effectively boost energy density and power density, which are critical requirements to achieve long travel distances, fast-charging, and reliable safety performance for electric vehicles. However, operating these batteries beyond the typical conditions of LIBs (4.3 V vs Li/Li+) leads to severe electrolyte decomposition, while interfacial side reactions remain elusive. These critical issues have become a bottleneck for developing electrolytes for applications in extreme conditions. Herein, an additive-free electrolyte is presented that affords high stability at high voltage (4.5 V vs Li/Li+), lithium-dendrite-free features upon fast-charging operations (e.g., 162 mAh g−1 at 3 C), and superior long-term battery performance at low temperature. More importantly, a new solvation structure-related interfacial model is presented, incorporating molecular-scale interactions between the lithium-ion, anion, and solvents at the electrolyte–electrode interfaces to help interpret battery performance. This report is a pioneering study that explores the dynamic mutual-interaction interfacial behaviors on the lithium layered oxide cathode and graphite anode simultaneously in the battery. This interfacial model enables new insights into electrode performances that differ from the known solid electrolyte interphase approach to be revealed, and sets new guidelines for the design of versatile electrolytes for metal-ion batteries.