bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Synthetic Exploration of Functional Nanographenes for Photonic Applications
Authors: Narita Akimitsu
Published: September 2023

Nanographenes, or large polycyclic aromatic hydrocarbons (PAHs), have been attracting renewed attentions for their unique optical, electronic, and magnetic properties [1]. Nanographenes can also be considered as atomically precise graphene quantum dots (GQDs), which are promising as an environmentally friendly alternative of semiconductor quantum dots, especially for photonic applications ranging from light-emitting devices to bioimaging. To this end, we have been exploring the synthesis and functionalization of dibenzo[hi,st]ovalene (DBOV) as a nanographene with zigzag and armchair edges, which demonstrated high stability, strong red emission, and optical gain properties [1,2]. For example, the functionalization of DBOV with two fluoranthene imide (FAI) groups induced red-shift of the absorption and emission bands, increase of the Stokes shift, and enhancement of the stimulated emission (SE) signals with significantly reduced excited state absorption, allowing the efficient lasing at 720 nm [3]. More recently, we have synthesized dibenzo[a,m]dinaphtho[3,2,1-ef:1',2',3'-hi]coronene (DBDNC) with armchair, zigzag, and fjord edges, which also showed high stability and red emission [4]. Notably, DBDNC has a nonplanar structure around the fjord edges, as revealed by the single-crystal X-ray analysis, and displayed a SE signal at 710 nm with a longer lifetime than that of DBOV, presumably due to the suppression of intermolecular interactions. These results provide a further insight into the relationship between the PAH structures and their photophysical properties, paving the way toward their photonic applications.

[1] Paternò, G. M.; Goudappagouda, Chen, Q.; Lanzani, G.; Scotognella, F; Narita A., Adv. Optical Mater. 2021, 9, 2100508.

[2] Paternò, G. M.; Chen, Q.; Wang, X.-Y.; Liu, J.; Motti, S. G.; Petrozza, A.; Feng, X.; Lanzani, G.; Müllen, K.; Narita, A.; Scotognella, F., Angew. Chem. Int. Ed.
2017,
56, 6753–6757.

[3] Paternò, G. M.; Chen, Q.; Muñoz-Mármol, R.; Guizzardi, M.; Bonal, V.; Kabe, R.; Barker, A. J.; Boj, P. G.; Chatterjee, S.; Ie, Y.; Villalvilla, J. M.; Quintana, J. A.; Scotognella, F.; Müllen, K.; Díaz-García, M. A.; Narita, A.; Lanzani, G., Mater.
Horiz. 2022,9, 393–402.

[4] Xu, X.; Serra, G.; Villa, A.; Muñoz-Mármol, R.; Vasylevskyi, S.; Gadea, M.; Lucotti, A.; Lin, Z.; Boj, P. G.; Kabe, R.; Tommasini, M.; Díaz-García, M. Á.; Scotognella, F.; Paternò, G. M.; Narita, A., Chem. Sci.
2022, 13, 13040–13045
(Invited) Effect of the Electron-Donating and Electron-Withdrawing Substituent on the Diels-Alder Cycloaddition Reaction of Hemifullerenes with 1,3-Butadiene
Authors: Mojica Martha , Méndez Francisco , Alonso Julio A. , Richaud Arlette , López María J.
Published: September 2023

In the search for an efficient method to synthesize C60, the dimerization strategy of two C30H12 fragments has been considered (1,2). Scott et. al. (3) have demonstrated that the Diels-Alder cycloaddition reaction in the bay regions of a polycyclic aromatic hydrocarbon (PAH) can occur at low temperatures (below 150ᵒC), they have also shown that the use of nitroethylene as masked-acetylene in a DA reaction over the bay regions of perylene and 7,14-dimesitylbisanthene leads to a rapid conversion of the bay regions of the PAH to new unsubstituted benzene rings (4) .This findings allow us to think that the use of a set of substituents on the C30H12 fragment would be a good strategy to favor the DA reaction of substituted C30H12 fragment with butadiene and reduce the activation energies of the reaction. Our previous calculations showed that the DA reaction of 1,3-butadiene with the rim of the C30H12 fragment might be possible, having an activation energy close to that calculated for the DA reaction with 1,3-butadiene and ethylene (5). In this work a theoretical study of the electronic, thermodynamic and kinetic parameters of the Diels-Alder reaction of butadiene with the rims of the substituted C30H12 fragments (triindenetriphenylene 1 and pentacyclopentacorannulene 2) as well as the aromatization of the obtained adducts was carried out (6).

(1) a) Scott, L.T. Angew. Chem. Int. Ed. 2004, 43, 4994.; b) Tsefrikas, V.M.; Scott, L.T. Chem. Rev. 2006, 106, 4868; c) Abdourazak, A.H.; Marcinow, Z.; Sygula, A.; Sygula, R.; Rabideau, P.W. J. Am. Chem. Soc. 1995, 117, 6410.

(2) Richaud, A.; López, M.J.; Mojica, M.; Alonso, J. A, Méndez, F. RSC Adv., 2020, 10, 3689.

(3) Fort, E.H.; Donovan, P.M.; L. T. Scott, L.T. J. Am. Chem. Soc., 2009, 131, 16006.

(4) E. H. Fort, L. T. Scott, Angew. Chem. Int. Ed. 2010, 49, 6626.

(5) Mojica, M.; Méndez, F.; Alonso, J.A. Molecules 2013, 18, 2243.

(6) Mojica, M.; Méndez, F.; Alonso, J.A. Molecules 2016, 21, 200.

Figure 1
(Invited) Photoinduced Electron Transfer in Dyads Involving Complexes of C60 and Nanohoops. Effect of π-Extension and Aromaticity of the Nanohoop
Authors: Solà Miquel , George Gibu , Stasyuk Olga A. , Stasyuk Anton , Voityuk Alexander A.
Published: September 2023

Conversion of the sunlight into chemical energy is considered to be one of the most important and fundamental chemical reactions in nature. A broad variety of artificial photosynthetic systems based on dyads, triads and up to pentads involving electron donor and acceptor moieties have been designed and synthesized in order to investigate artificial photoinduced energy and electron transfer processes. One type of dyads with potential applications in solar cells is the one combining C60 complexed with nanohoops.[1] In this work, we discuss a series of computational studies that involves the photoinduced charge separation in complexes of C60 and Li+@C60 with a series of different nanohoops, such as the [10]cycloparaphenylene ([10]CPP) ring,[2] π-extended CPPs such as the hexa-peri-benzocoronene (HBC) or the tribenzo[fj,ij,rst]pentaphene (TBP),[3] and [n]cyclodibenzopentalenes ([n]CDBPs) as antiaromatic curved nanorings.[4] The analysis of complexes of C60 with nanohoops having different degrees of π-conjugation and aromaticity allow us to discuss the effect in the charge transfer separation and recombination on the level of π-extension and aromaticity present in the nanohoops.

References

[1] (a) M. Hermann, D. Wassy, B. Esser, Angew. Chem. Int. Ed. 60 (2021) 15743–15766; (b) J. S. Wössner, D. Wassy, A. Weber, M. Bovenkerk, M. Hermann, M. Schmidt, B. Esser, J. Am. Chem. Soc. 143 (2021) 12244–12252.

[2] A. J. Stasyuk, O. A. Stasyuk, M. Solà and A. A. Voityuk, Chem. Commun. 55 (2019) 11195-11198.

[3] Manuscript in preparation.

[4] G. George, O. A. Stasyuk, A. A. Voityuk, A. J. Stasyuk and M. Solà. Nanoscale, in revision.

Figure 1
(Invited) Dynamics of Fullerenes Visualized with Variable Temperature Single-Crystal X-Ray Diffraction
Authors: Liu Fupin , Popov Alexey A.
Published: September 2023

The dynamics of fullerenes are fundamentally interesting. Variable temperature single-crystal X-ray diffraction is a powerful tool to view the temperature-driven dynamics of fullerene molecules in the crystal lattice because fullerene crystals present fruitful dynamics information in the widely accessible liquid nitrogen cryostats temperature range (90 K - room temperature). Recently, we succeeded in the visualization of the temperature-driven circular movement of Dy2 inside a benzyl-functionalized C80 cage in its solvate crystal.1 The temperature-driven dynamics of typical fullerene/nickel octaethylporphyrin (NiOEP) co-crystals presented the rather static behaviour of porphyrin molecules, and strong libration of the fullerene cages (C60 and C80) in the temperature range of 100-280 K. While the M3N clusters (M3N = Ho2LuN, Lu3N or Sc3N) inside C80 cage show intriguing temperature-driven dynamics with subtle metal atom size/mass effects.2-3 Sc3N@C70 rotation in the co-crystal with NiOEP induced a phase transition which was visualized with variable temperature single-crystal X-ray diffraction.4 In this contribution, the details of the recently observed temperature-dependent dynamics of fullerene molecules in the crystal lattice will be discussed.

Liu, F.; Velkos, G.; Krylov, D. S.; Spree, L.; Zalibera, M.; Ray, R.; Samoylova, N. A.; Chen, C.-H.; Rosenkranz, M.; Schiemenz, S.; Ziegs, F.; Nenkov, K.; Kostanyan, A.; Greber, T.; Wolter, A. U. B.; Richter, M.; Büchner, B.; Avdoshenko, S. M.; Popov, A. A., Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond. Nat. Commun.
2019,
10, 571.

Liu, F.; Spree, L., Molecular Spinning Top: Visualizing the Dynamics of M3N@C80 with Variable Temperature Single Crystal X-ray Diffraction. Chem. Commun.
2019,
55, 13000-13003.

Hao, Y.; Wang, Y.; Spree, L.; Liu, F., Rotation of fullerene molecules in the crystal lattice of fullerene/porphyrin: C60 and Sc3N@C80. Inorg. Chem. Front.
2021,
8, 122-126.

Hao, Y.; Wang, Y.; Dubrovin, V.; Avdoshenko, S. M.; Popov, A. A.; Liu, F., Caught in Phase Transition: Snapshot of the Metallofullerene Sc3N@C70 Rotation in the Crystal. J. Am. Chem. Soc.
2021,
143, 612-616.
Covalent Functionalization of Kevlar Fabric with Graphene Nanosheets
Authors: Sideri Ioanna K. , Canton-Vitoria Ruben , Vasilakos Sozon , Siamidis Dionysios , Tagmatarchis Nikos
Published: September 2023

Whilst technical textile requirements for personal protecting clothing have dramatically increased during the past years due to the climate and health crisis, as well as the human factor, garment industry is in search of new fabrics that will meet these emerging needs. Aiming in the realization of superior fabrics performing under extreme environmental and operational conditions, carbon nanostructures and graphene-related 2D nanomaterials offer their mechanical strength and functionalization capability in this new challenge.1 However, most techniques developed for the hybridization of fabric fibers with carbon nanostructures and related 2D nanomaterials are based on physisorption and surface coating. Herein, we present a protocol for the covalent modification of Kevlar fibers in order to generate free amine groups on their aromatic rings that can be chemically manipulated to covalently attach graphene nanosheets. In particular, Friedel-Crafts type nitration of Kevlar fibers, followed by hydrogenation to furnish amine moieties, allows condensation with a small amino acid that serves as the connector with oxidized graphene flakes (Figure 1).2 Optimized conditions and in depth spectroscopic study are provided that collectively offer an easy-monitoring protocol of each step and allow the transfer of this knowledge to other related 2D nanomaterials. Considering the ability of 2D nanomaterials to carry designed properties via functionalization, this methodology allows the realization of multipurpose custom fabrics with enhanced qualities of choice.

Partial financial support by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH-CREATE-INNOVATE (project code: Τ2EDK-01316) is acknowledged.

References

[1] I. K. Sideri, N. Tagmatarchis, Mater. Horiz., 2021, 8, 3187.

[2] Manuscript in preparation.

Figure 1
Comparison of Precursors for Self-Assembled Monolayers as Cu Barrier
Authors: Cheng Yi-Lung , Lee Chih-Yen
Published: September 2023

Self-assembled monolayers (SAMs) are the emerging materials as the candidate of barriers for application in back-end-of–line interconnects in advanced generation. In this study, SAMs derived from organic molecules with different structures are compared in terms of electrical characteristics, Cu diffusion inhibition, and Cu–SiO2 adhesion promotion. Experimental results indicated that all SAMs formed in this study enhance the breakdown filed of SiO2 film, promote Cu–SiO2 adhesion, and prevent Cu-silicate formation under thermal annealing. Among the studied SAMs, APTMS-SAM derived from 3-aminopropyltrimethoxysilane (APTMS) has the most pronounced enhancement. Moreover, APTMS-SAM blocks Cu migration under electrical stress. The terminal group -NH2 attached to Cu layer in the APTMS is the key in the improvement.
Symmetric Electrochemical Supercapacitors Based on Electrodes of Graphene Nanoribbons/Iron-Doped Lanthanum-Strontium-Manganese Based Perovskite Oxides
Authors: Heiba Asmaa R. , Abou Shahba Rabab M. , Dhmees Abdelghaffar S , Taher Fatma A , El Sawy Ehab
Published: September 2023

The dramatic increase in the world population and industrialization have resulted in unprecedented levels of humanity's hunger for energy. The total global energy production has increased from 23 in 1900 to 548 Exajoules (1018 J = EJ) in 2016.1 A significant contribution of the internment renewable energy resources to the energy production before the mid of this century becomes a necessity to significantly reduce fossil fuel usage and hence limit global warming.1 This creates a great incentive to identify the best ways to store energy when it is not needed.

Supercapacitors have gained significant attention due to their fast charging/discharging speed, high power density, and long-term cycling stability in contrast to traditional batteries.2 In recent years, perovskites and graphene nanoribbons have been significantly considered promising materials for electrochemical energy storage. The graphene-based materials have a highly tunable surface area, outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior.3 While the perovskite materials provide the possibility of both anionic and cationic storage mechanisms.4

This presentation reports the in situ preparation of iron-dopped lanthanum-strontium-manganese-based perovskite oxides (La0.7Sr0.3MnxFe1-xO3-δ, LSMFO) in the presence of graphene nanoribbons (GNRs), and the evaluation of the supercapacitive behavior of the synthesized composites. The physical/chemical structure of LSMFO was evaluated using XRD, TEM, FT-IR, Raman spectroscopy, EDS, BET, and XPS. Integrating the perovskite materials that possess redox reaction ability with graphene nanoribbons that exhibit good electronic properties is found to improve the supercapacitor performance in comparison to the single components. The symmetric supercapacitor devices based on LSMFO/GNRs showed good stability (capacitive retention of 95% over 10,000 cycles at a higher current density of 10 A g-1), a wide potential window (up to 1.7 V), and a relatively high capacitance. The best composite with optimum LSMFO:GNRs ratio that shows the highest supercapacitance is identified and explained in correlation with its surface chemical structure.

References

G. A. Jones and K. J. Warner, Energy Policy, 93, 206–212 (2016).

S. Ghosh, K. Anbalagan, U. N. Kumar, T. Thomas, and G. R. Rao, Applied Materials Today, 21, 100872 (2020).

O. D. Salahdin et al., Appl. Phys. A, 128, 703 (2022).

B.-M. Kim et al., Sci Rep, 12, 10043 (2022).
Cascaded Compression of the Size Distribution of Nanopores in Monolayer Graphene
Authors: Wang Jiangtao , Cheng Chi , Kong Jing
Published: September 2023

Nanoporous graphene has shown great promise for membrane separations. Its atomic thickness, remarkable mechanical, chemical, and thermal robustness could enable ultrahigh-flux membrane processes addressing persistent challenges in a wide range of separation needs. On the other hand, molecular separations across nanoporous graphene rely dominantly on size-based mechanisms (e.g, size exclusion) that is highly sensitive to the nanopore size and size distribution of nanopore ensemble created on the graphene. However, among existing nanopore creation methods, the process of nanopore nucleation is often coupled with nanopore expansion, which results in a lognormal nanopore size distribution with a long tail. It remains a challenge to obtain both high density and narrow size distribution of nanopores in graphene. Here, we report a cascaded compression approach to engineering nanopores in monolayer graphene for molecular separations with the assistance of electrical control of chemical vapor deposition of graphene[1]. The formation of nanopores is split into many small steps, in each of which the size distribution of all the existing nanopores is compressed by a combination of shrinkage and expansion, and at the same time of expansion, a new batch of nanopores is created, leading to increased nanopore density by each cycle. As a result, high-density nanopores with a short-tail size distribution are obtained by the cascaded compression that show high rejection and ultrafast organic solvent nanofiltration exceeding the state-of-the-art.

Reference

[1] Wang J, Park J H, Lu A Y, et al. Electrical Control of Chemical Vapor Deposition of Graphene. Journal of the American Chemical Society, 20
(Invited) Laser-Induced Graphene on Polymers: From Process Science to Applications
Authors: Bedewy Mostafa
Published: September 2023

Nanocarbons like graphene and carbon nanotubes (CNTs) are promising for various applications including advanced electronic devices, novel energy systems, and next-generation healthcare diagnostics. This is owing to the excellent physical, chemical and electrochemical properties arising from the ordered atomic structure, the hierarchical nanoscale morphology, and tunable chemistry of nanocarbons. In particular, low-dimensional carbon electrodes for biosensors and neural interfaces have consistently been shown to have superior performance when compared to state-of-the-art metal electrodes. Nevertheless, major manufacturing challenges still hinder our ability to scalably produce graphene-based electrodes with tailored morphology and surface chemistry, especially on flexible substrates. While chemical vapor deposition (CVD) processes enable the synthesis of high quality graphene and CNTs, the extreme environments of high temperatures and hydrocarbon-rich gaseous atmosphere in such reactors limit the choice of substrates to silicon, quartz, metals or other rigid temperature-resistant materials. On the other hand, many emerging flexible devices require the fabrication of such nanocarbon electrodes on the surface of polymer substrates. Unlike different transfer technique of CVD-grown nanocarbons, this talk will focus on a unique bottom-up approach for directly growing different types of graphenic nanocarbons on polymer films by laser irradiation. The speaker will show how this direct-write process, often referred to as laser-induced graphene (LIG), can be controlled to produce spatially-varying morphologies and chemical compositions of LIG electrodes, by leveraging gradients of laser fluence. Moreover, a method will be introduced to control the heteroatom doping of these LIG electrodes based on controlling the molecular structure of the polymer being lased. Finally, a demonstration of these functional LIG electrodes as electrochemical biosensors will be presented for the detection of the neurotransmitter dopamine with nanomolar sensitivity.
(Invited) Graphene-Based Scaffolds for Electrochemical Energy Storage
Authors: Chandrasekaran Swetha , Lin Dun , Reale Batista Mariana Desiree , Li Hanyu , Carleton Adam , Xue Xinzhe , Luo Yunkai , Hu Bintao , Moran Bryan , Roy Thomas , Orme Christine , Dunn Bruce S. , Li Yat , Worsley Marcus Andre
Published: September 2023

The efficient transport of charge species within energy storage devices is critical to realizing both large power and energy densities, especially when operating under extreme conditions (e.g. ultralow temperatures, high charge/discharge rates, etc.). A number of resistances can contribute to sluggish ion/electron transport in a cell such as charge transfer at interfaces, electrolyte resistance, electrode resistance, and diffusive transport within porous electrodes. Several strategies have been pursued to address these transport limitations. Electrolyte engineering is an effective approach as it can influence both electrolyte resistance and charge transfer resistances. Electrode materials discovery and development is another popular strategy as the charge storage mechanism and electrode resistance play a key role in kinetics of the device. Within electrode materials development, engineering of the electrode pore architecture is an extremely effective strategy to decrease the diffusive transport lengths and electrode resistances. This pore engineering can be achieved through synthetic chemistry for small pores (e.g. <10 um) and via additive manufacturing for larger pores (> 10 um). Here we show how electrolyte engineering and electrode materials development can be used to overcome sluggish transport in graphene-based electrodes. Particular focus will be given to the use of synthetic means to tune to the properties of a graphene aerogel scaffold (e.g. surface area, pore size, mechanical properties) and additive manufacturing to define the larger pore structure to facilitate uniform deposition of active materials (e.g. MnO2) and improve energy density and rate capability of the energy storage device. We explore a number of additive manufacturing techniques (e.g. direct ink write, projection microstereolithography, etc.) to print a variety of lattice structures and computer-guided designs to determine the optimal electrode architecture.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Invited) Controlling the Layer Stacking and Twisting of 2D Quantum Materials
Authors: Jin Song
Published: September 2023

Rationally and precisely controlling the structures of two-dimensional (2D) layered materials allows us to tune the electronic structures and quantum states of matter, discover new physical properties, thus enable new applications. For example, tuning the twist angles between 2D materials results in the formation of moiré patterns and the manipulation of electronic states, which have led to novel quantum phenomena, including unconventional superconductivity, moiré excitons, and tunable Mott insulators. We have shown how the phase, layer stacking and thus physical properties of 2D MX2 materials can be influenced by screw dislocations. Moreover, we achieved systematic interlayer twisting of MX2 spiral layers grown via by screw dislocations due to mismatched geometry between Euclidean crystal lattices and non-Euclidean (curved) surfaces (Science
2020, 370, 442). We experimentally demonstrated the growth of twisted spirals of WS2 and WSe2 draped over nanoparticles near their centers and microscopic structural analysis confirmed the moiré superlattices between the atomic layers. Tuning the stacking and twisting of 2D materials opens up new dimensions of 2D quantum materials (Acc. Mater. Res.
2022, 3, 369) for the study of moiré excitons, nonlinear optical properties, chiral optoelectronics, valleytronics and twistronics.
(Invited) Understanding Strain and Deformation in 2D Materials Via 4D-STEM and Cryo-EM
Authors: Han Yimo
Published: September 2023

Strain and deformations play a critical role in the mechanical, electrical, and chemical properties of two-dimensional (2D) materials due to their atomic thinness. This presentation will discuss using the state-of-the-art transmission electron microscopy (TEM) techniques to study the strain and deformations in 2D materials. First, the speaker will introduce the study of strain relaxation in epitaxial lateral heterojunctions of 2D transition metal dichalcogenides (TMD) using nano-beam four-dimensional scanning TEM (4D-STEM)1. By developing an unsupervised learning approach, we were able to accelerate and automate the method for more general users2. In addition, the speaker will also present the direct visualization of the floppiness of 2D DNA origami using cryo-EM. The work uncovers flexible arms in 2D cross tiles, as well as clusters and stacks, which may potentially affect the assembly of DNA origami3.

Han, Y. et al. Strain Mapping of Two-Dimensional Heterostructures with Subpicometer Precision. Nano Letters 18, 3746–3751 (2018).

Shi, C. et al. Uncovering material deformations via machine learning combined with four-dimensional scanning transmission electron microscopy. Npj Comput Mater 8, 114 (2022).

Ni, H. et al. Direct visualization of floppy two-dimensional DNA origami using cryogenic electron microscopy. Iscience 25, 104373 (2022).
Bonding-Driven Crystallization of Dimensionally Resolved Nanostructures Based on Quasi-1D Van Der Waals Building Blocks
Authors: Arguilla Maxx , Cordova Dmitri Leo Mesoza , Allison Steven Jay
Published: September 2023

The discovery of complex phenomena and strongly correlated behavior in the solid state has incessantly relied upon the creation of stable low-dimensional lattices approaching the atomic limit. Whereas 2D van der Waals (vdW) materials with atomic scale thicknesses have gained widespread interest, very little has been known about the chemistry and physics of their more confined 1D counterparts in the solid state. In these length scales and dimensionalities, unique physical properties arising from finite size effects such as ballistic electrical transport, size-dependent optical resonance modes, long carrier lifetimes, and exotic higher-order topological states become realizable. To this end, I will present the recent efforts in my group towards elucidating the chemical bonding interactions which define the structure and nanoscale dimensionality of structures derived from lattices which are comprised of 1D chains with sub-nm diameters that are held together by weak vdW interactions. By gaining anisotropy-driven control over these interactions via bottom-up chemical vapor growth, we demonstrate the creation of dimensionally-resolved nanostructures with various thicknesses ranging from 1D nanowire bundles to quasi-2D nanoribbons and nanosheets, all based on a the same 1D vdW lattice motif. Extensive electron diffraction and atomic-resolution microscopy of these resulting nanostructures reveal the strong dependence of the size and dimensionality of the 1D and quasi-2D nanostructures on anisotropic inter-chain vdW bonding interactions, precursor ratios, and growth temperatures. Using these results, we propose a crystallization mechanism defined by the competition between covalent and vdW bonding interactions and epitaxy. As physical properties directly correlate to the structure, dimensionality, and size in the solid state, I will also talk about how the unique topographies of resulting freestanding nanostructures dictate their electronic properties. I will describe how the synthetic control over the structural attributes led to our discovery of emergent properties such as the elusive indirect-to-direct band gap transition and higher-order topological states in 1D vdW nanostructures. Through these efforts, we define for the first time the anisotropy-driven growth of these emergent 1D vdW-derived nanostructures and how nanoscale morphologies in these nanostructures dictate their electronic structures. Altogether, this precise control over crystalline and electronic structure poises these emergent low-dimensional solids as building blocks towards programmable electrocatalysts, densified electronic and quantum devices in sensing, photonic, energy storage and conversion, and spintronic technologies.
Hexagonal Hybrid Bismuthene by Molecular Interface Engineering
Authors: Abellán Gonzalo
Published: September 2023

Novel, high quality devices, based on layered heterostructures are typically built from materials obtained by complex solid-state physical approaches or laborious mechanical exfoliation and transfer, as wet-chemically synthesized materials commonly suffer from surface residuals and intrinsic defects. Here, we introduce a new 2D member to the pnictogen family, synthetized by a colloidal approach, that consists of a coherent sandwich of beta-bismuth, encapsulated by sulfur-alkyl-functionalized flat bismuthene interfaces. While an unprecedented degree of structural quality is demonstrated, an altered atomic arrangement of the outermost, functionalized bismuthene layers leads to a drastic changes in the chemical reactivity and electronic structure. The metallic nature is evidenced by room temperature transport measurements of individual nanoflakes. Our data proof that surface reconstructions in 2D systems can promote unexpected new states that can pave the way to new functionalities and devices. Last but not least, a large scale production strategy will be introduced.
Revealing Local Structure and Dynamics in Li-Salt Electrolytes Using Dielectric Relaxation Spectroscopy
Authors: Paren Benjamin , Leverick Graham , Burke Benjamin , Lopez Jeffrey , Shao-Horn Yang
Published: September 2023

Understanding the interplay between local structure and dynamics is critical for establishing design rules for advanced ion-conducting electrolytes. In this work, a set of Li-salt in liquid electrolytes is studied using dielectric relaxation spectroscopy (DRS) to examine correlations between several electrolyte properties, including conductivity, dielectric relaxation time and strength, ionicity, and viscosity. These properties were evaluated by changing ion concentration, solvent type, and anion type. DRS was used to identify relaxation processes associated with the solvent and different ion-solvent coordinating structures, and the dielectric properties are reported for the first time for a majority of these systems. The behavior of viscosity and conductivity were shown to change similarly with concentration when accounting for the local coordinating environment, regardless of the salt or solvent type. τα, the dielectric relaxation time of the solvent-ion complexes, is shown to be independent of ion content at low salt concentrations, when solvent separated ion pairs are the dominant ion-solvent complex. However, at high ion concentrations, a new relationship, a power-law dependence, was identified between molar conductivity and τα, as well as viscosity and τα, demonstrating that the dependence of molar conductivity or viscosity on τα is controlled in part by the solvent type, due to variation in shielding between contact ion pairs and aggregates. In contrast, there was not a clear change in the dependence of molar conductivity or viscosity on τα with changing anion. Furthermore, the effective dipole moments of the ion-solvent complexes were determined, and found to decrease with increasing ion concentration, as contact ion pairs and aggregates form. This systematic analysis of the wide range of Li-salts and solvents, and discussion of relations between different local structures and dynamic processes that contribute to conductivity, helps lay a foundation for the design of new liquid electrolytes.
Lithium-Ion Diffusivity Increases with Block Size in Niobium Tungsten Oxide Shear Structures
Authors: Sambur Justin
Published: September 2023

Nb16W5O55 emerged as a high-rate anode material for Li-ion batteries in 2018 (Griffith et al.,Nature
2018, 559 (7715), 556–563). This exciting discovery ignited research in Wadsley-Roth (W-R) compounds, but systematic experimental studies have not focused on how to tune material chemistry and structure to achieve desirable properties for energy storage applications. In this work, we systematically investigate how structure and composition influences capacity, Li-ion diffusivity, charge-discharge profiles, and capacity loss in a series of niobium tungsten oxide W-R compounds: (3×4)-Nb12WO33, (4×4)-Nb14W3O44, and (4×5)-Nb16W5O55. Potentiostatic intermittent titration (PITT) data confirmed that Li-ion diffusivity increases with block size, which can be attributed to an increasing number of tunnels for Li-ion diffusion. The small (3×4)-Nb12WO33 block size compound with preferential W ordering on tetrahedral sites exhibits single electron redox and, therefore, the smallest measured capacity despite having the largest theoretical capacity. This observation signals that introducing cation disorder (W occupancy at the octahedral sites in the block center) is a viable strategy to access multi-electron redox behavior in (3×4) Nb12WO33. The asymmetric block size compounds (i.e., (3×4) and (4×5) blocks) exhibit the greatest capacity loss after the first cycle, possibly due to Li-ion trapping at a unique low energy pocket site along the shear plane. Finally, the slope of the charge-discharge profile increases with increasing block size, likely because the total number of energy-equivalent Li-ion binding sites also increases. This unfavorable characteristic prohibits the large block sizes from delivering constant power at a fixed C-rate more so than the smaller block sizes. Based on these findings, we discuss design principles for Li-ion insertion hosts made from W-R materials.
Rechargeable Silicon-Ion Batteries
Authors: Epshtein Alon , Baskin Igor , Ein-Eli Yair
Published: September 2023

Silicon (Si) is the second abundant material in nature and yet, despite its high abundance and ease of production, the possibility of using Si as an active multivalent rechargeable anode was never explored or reported. As a proof of concept, we will discuss in this talk a new rechargeable Si-ion cell, its design and architecture, enabling Si to be reversibly discharged at 1.1 V and charged at 1.5 V. Several discharge-charge cycles were achieved, utilizing heavy doped n-type Si wafer anodes, and hybrid based ionic liquid electrolytes. In addition, dissolved halides are functioning as conversion cathodes. Cell characterizations correlated the discharge and charge processes with the presence of dissolved fluoride and Si species in the electrolyte. The presence of appreciable fluoride species is crucial in both establishing surface activation and battery operation, and their depletion is directly linked to cell performance degradation. We will discuss Si ions deposition and dissolution mechanisms.
Ammonium Vanadium Bronze As a Cathode Material for Calcium-Ion Batteries
Authors: Bu Hyeri , Hyoung Jooeun , Heo Jongwook W , Hong Seung-Tae
Published: September 2023

Calcium-ion battery (CIB) is considered one of the attractive candidates for post-Li-ion batteries. However, few cathode materials intercalate Ca ions reversibly in nonaqueous electrolytes. Herein, we report the discovery of novel ammonium vanadium bronze (NVO) as a host material of CIBs. We synthesized NVO via a facile hydrothermal method. We determined its chemical composition and crystal structure (P-1) from single-crystal X-ray diffraction data for the first time, revealing unprecedented stoichiometry and crystal structure. It comprises V7O16 layers stacking along the c-axis and two NH4
+ ions occupying the interlayer space per formula unit. The galvanostatic discharge/charge cycling demonstrates reversible electrochemical intercalation of Ca2+ ions into the structure. The discharge capacities are ~98 and 87 mAh g-1 for the first and second cycles, respectively. On charge, NH4
+ ions are de-intercalated. Simultaneously, the ion-exchange reaction occurs: a small amount of Ca2+ ions are chemically exchanged for NH4
+ ions. On discharge, cation insertion occurs, mainly Ca2+ ions and partially the extracted ammonium ions. Small amounts of reinserted ammonium ions play an important role in structural stability, enabling better cycle performance. Understanding the newly discovered mechanism of this material is expected to provide general insights into ammonium vanadium bronzes as new cathode materials.
(Invited) Progress in Materials and Process for Sustainable Perovskite Solar Cells
Authors: Jung Hyun Suk
Published: September 2023

All solid-state solar cells based on organometal trihalide perovskite absorbers have already achieved distinguished power conversion efficiency (PCE) to over 25% and further improvements are expected up to 27%. Now, the research on perovskite solar cells (PSCs) has been moving toward commercialization. To facilitate commercialization of these great solar cells, some technical issues such as long-term stability, large scale fabrication process, and Pb-related hazardous materials need to be solved. Also, flexible perovskite solar cell using plastic substrate can be used in niche applications such as portable electrical chargers, electronic textiles, and large-scale industrial roofing.

This talk is dealing with our recent efforts to facilitate commercialization of perovskite solar cells. For examples, we introduce a recycling technology of perovskite solar cells, which covers the regeneration process of Pb contained perovskite layer as well as recycling process of Au electrodes and transparent conducting oxide glass. Also, simple fabrication technologies for realizing large scale perovskite module are introduced and recent effort for achieving high efficiency module is going to be presented. Finally, recent interesting results regarding ultra flexible perovskite cells will be discussed.
Conductivity in Thin-Films of Transition Metal Coordination Complexes
Authors: Spinelli Giovanni , Freitag Marina
Published: September 2023

In electronic commercial devices silicon remains the dominant material. Although it shows many advantages it requires usually high energy demand processes. Moreover, modifications of the electronic and physical properties are usually coupled with those processes.[
1
] While organic semiconductors usually show low energy processes and deposition with the desirable tunability reached with well-established synthesises.[
2
] Coordination complexes can even have an easier way of tunability by simply change the metal cores involved in the formation of the compounds. We aimed to design two coordination compounds formed by two complexes with equal but opposite charge and checking how the conductivity changes upon the metal substitution. They were synthetised by metathesis reaction by combining dithiolene complexes [M(mnt)2]2- (mnt = maleonitriledithiolate) M = Ni2+, Cu2+ with a copper coordination complexes [Cu(Stetra)]2+ (Stetra = 6,6’-bis(4,5-dihydrothiazol-2-yl)-2,2’-bipyridine). Upon the substitution of the metal core the system passed from insulator (Ni) to semiconductor behaviour (Cu) with a value of 10-8 (S/cm) and an activation energy of 0.9 eV. Their properties were investigated by using UV-Vis absorption, cyclic voltammetry, Raman spectroscopy, powder XRD, and conductivity. UV-Vis absorption and cyclic voltammetry were performed, in solid state, for the approximation of the energy levels. To support our investigations and experimental results computational modelling was performed. It revealed the central role that the copper has upon the conductivity compared to nickel. The lower reorganisation energy showed by the copper complex Cu(mnt)2
2- in solid state results in a lower energy barrier and a more favourable hopping mechanism through the molecules.

Segal, M. Material history: Learning from silicon. Nat. 2012 4837389
483, S43–S44 (2012).

Koch, N. Opportunities for energy level tuning at inorganic/organic semiconductor interfaces. Appl. Phys. Lett.
119, 260501 (2021).

Figure 1
(Invited) Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System
Authors: Mitsunuma Harunobu , Fuse Hiromu , Irie Yu , Fuki Masaaki , Kobori Yasuhiro , Kato Kosaku , Yamakata Akira , Higashi Masahiro , Kanai Motomu
Published: September 2023

The carbon-hydrogen (C-H) bond is a fundamental chemical bond that constitutes organic molecules, and its direct conversion leads to highly efficient molecular synthesis. In recent years, the hydrogen atom transfer (HAT) catalysis using the energy of visible light, has been attracting attention. However, existing methods require the use of photoredox catalysts such as organic molecules with complex structures and expensive metal complexes. In this study, we developed an organocatalytic system that mimics the electron transfer process of enzymes in vivo and promotes functionalization of stable C-H bond without photoredox catalyst. We designed a thiophosphoric acid catalyst that contains both a redox-active binaphthyl moiety and a sulfur atom. We found that this catalyst forms charge-transfer complexes with electron-deficient heteroaromatics and catalytically produces thyil radical via multi-step electron transfer under visible light irradiation.

Based on the above design, we decided to investigate the formation of active HAT catalytic species in the absence of photoredox catalysis by the Minisci-type reaction using aldehydes and N-heteroaromatic rings. The results of the study confirmed that 29% of the product was obtained when using binaphtyl thiophosphoric acid (TPA) catalyst, as expected. Yield improved to 80% when an electron-donating group was introduced to the binaphthyl skeleton to enhance the donor-acceptor interaction. Changing the binaphthyl skeleton and thiophosphoric acid moieties markedly reduced reactivity, indicating that the presence of a sulfur atom in addition to a rigid binaphthyl skeleton is essential for the efficient reaction progress. With this optimized condition, alkylation of N-heteroaromatic rings by C-H bond activation of alcohols was found to proceed. Dehydrogenation of alcohols and benzylation of imines were also successfully achieved by using N-heteroaromatic catalyst. The mechanism of the electron transfer process has been confirmed by spectroscopic and computational methods, and will be presented in detail in the lecture.

Figure 1
(Invited) Synthesis and Photophysical Properties of Cyclometalated Iridium(III) Complexes Having Arylborane Units Toward the Photoreaction
Authors: Sakuda Eri
Published: September 2023

Cyclometalated iridium(III) complexes are known to show intense absorption and bright phosphorescence at room temperature and have been applied to photosensitizer and light-emitting materials. For such applications of the complexes, the study of synthetic tuning of the HOMO/LUMO energies of the complexes through introduction of electron-withdrawing substituent(s) on the ligand and/or that of heteroaromatic ring(s). By introducing another interaction site into Ir complexes, it is considered that a more sensitive HOMO/LUMO energies change occurs. Therefore, we focused on the arylborane compounds. When boron has a tri-substituted structure, it has an vacant p-orbital and has a planar structure. Since this vacant p-orbital shows Lewis acidity, it is considered that it acts as an acceptor site. Furthermore, the excited-states of arylborane derivatives are expected to be utilized to photoinduced electron transfer systems. Therefore, in this study, we synthesized a novel iridium(III) complexes having various boron substituents, which is thought to cause intramolecular charge transfer, and investigated its spectroscopic properties.

Figure 1
(Invited) 5,15-Diazatetrabenzoporphyrins: Evaluation as Organic Semiconductors
Authors: Yamada Hiroko , Matsuo Kyohei
Published: September 2023

Tetrabenzo-5,15-diazaporphyrin (TBDAP) is a structural hybrid molecule of tetrabenzoporphyrin (TBP) and phthalocyanine (Pc). As compared with TBP, TBDAP has energetically lower HOMO and LUMO because of the higher electronegativity of nitrogen atom at meso-position. Moreover, its optoelectronic properties, solubility and molecular arrangement in the solid state can be controlled by introducing various substituents at another meso-carbons. These electronic and structural tunabilities of TBDAP are advantageous to the organic electronic application such as organic field-effect transistors (OFETs) and organic photovoltaics (OPVs), but selective and efficient synthetic methods for TBDAP are limited. Triisopropylsilyl (TIPS)-ethynyl group is one of the most popular substituents for organic semiconducting molecules. We synthesized 5,15- bis(triisopropylsilylethynyl)tetrabenzoporphine (TIPS-TBP) and its metal complexes. TIPS-TBP has reasonable solubility for solution-processed OFETs and exhibits excellent hole mobilities of 1.1 cm2 V−
1 s−
1 and 2.16 cm2 V−
1 s−
1 in dip-coating FET and single-crystal FET, respectively [1, 2]. These values are higher than that of pristine free-base TBP (0.07 cm2 V−1 s−1), indicating that TIPS-ethynyl group is also useful for porphyrin analogues. Herein, we report the synthesis of 10,20-bis(triisopropylsilylethynyl)tetrabenzo-5,15-diazaporphine (TIPS-TBDAP) by metal-template aza-annulation reaction [3,4]. TIPS-TBDAP exhibited efficient far-red fluorescence in solution and formed one-dimensional (1D) columnar structure in crystal packing. Its charge transporting property evaluated by preparing dip-coating FET and single-crystal FET will be also reported.

References

[1] K. Takahashi, B. Shan, X. Xu, S. Yang, T. Koganezawa, D. Kuzuhara, N. Aratani, M. Suzuki*, Q. Miao*, H. Yamada*, Engineering Thin Films of a Tetrabenzoporphyrin toward Efficient Charge-Carrier Transport: Selective Formation of a Brickwork Motif. ACS Appl. Mater. Interfaces 2017, 9, 8211-8218.

[2] J. Zhu, H. Hayashi*, M. Chen, C. Xiao, K. Matsuo, N. Aratani, L. Zhang, H. Yamada*, Single crystal field-effect transistor of tetrabenzoporphyrin with one-dimensionally extended columnar packing motif exhibiting efficient charge transport property J. Mater. Chem. C 2022, 10, 2527-2531.

[3] Y. Sugano, K. Matsuo*, H. Hayashi, N. Aratani, H. Yamada*, Synthesis of 10,20-substituted tetrabenzo-5,15-diazaporphyrin copper complexes from soluble precursors. J. Porphyrins Phthalocyanines 2021, 25, 1186-1192.

[4] Y. Sugano, K. Matsuo*, H. Hayashi, N. Aratani, H. Yamada*, Synthesis and properties of 10,20-bis(triisopropylsilylethynyl)-tetrabenzo-5,15-diazaporphine. J. Porphyrins Phthalocyanines 2022, 26, in press.
(Invited) Observation of Free Carriers in Non-Fullerene Acceptors with Broadband Mid-Infrared Transient Absorption Spectroscopy
Authors: Yamakata Akira , Kato Kosaku , Urakami Takumi , Sato Hirofumi , Higashi Masahiro , Umeyama Tomokazu , Imahori Hiroshi
Published: September 2023

Non-fullerene acceptors (NFAs) are attracting much attention as a material for efficient organic photovoltaics (OPVs). However, the photoinduced dynamics of NFAs has yet to be fully revealed. It is still questionable whether free carriers can be generated in the film consisting of the stacking of small NFA molecules. Transient absorption (TA) spectroscopy is a powerful method to investigate photoexcited states with ultrafast time resolution. TA spectroscopy in the visible and NIR region enables us to observe strongly bound photoexcitation states, but cannot detect free carriers. On the other hand, broadband MIR TA measurement makes it possible to observe free carriers. However, this is not commonly employed for the study of OPV. Herein, we investigated the photoexcited dynamics in the film of ITIC, one of the most well-known NFAs, by using MIR to visible TA measurement. In the MIR TA spectra, a peak around 3100 cm-1 and a broader component extending to lower energy region were observed. The latter broadband component got increased by blending ITIC with a donor, suggesting that this can be attributed to free carriers generated by charge separation. The observation of the vibrational frequency shift of CN group also supported the charge separation in the ITIC film. This study highlights the utility of MIR-TA spectroscopy in the study of OPVs.