bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Nanotube Based Low Reflective Coatings
Authors: WANG DAN , Hall Timothy , Snyder Stephen , Inman Maria , Taylor E. Jennings , Hopkins Alan , Fuqua Peter , Labatete-Goeppinger Aura , Hennessy Amber , Hoskinson Alan , Oakes David
Published: July 2021

Low reflective coatings or surfaces have wide applications in the fields of aerospace, energy, military, defense, and daily life. Optical baffles and sensors are important components of space-borne instruments, which require low-reflectivity surfaces to minimize stray and reflected light for improving their image resolution to facilitate the direct exoplanet detection and characterization, as well as the sensitivity for missile defense and satellite-based surveillance systems. The excellent mechanical, thermal, optical, and electrical properties of carbon nanotubes (CNTs) make them as ideal coating materials for obtaining low reflectivity surfaces for various applications.

In this presentation, Faraday Technology Inc. demonstrated the feasibility of a low-cost, efficient and scalable manufacturing process for the deposition of durable, low reflectivity carbon nanotube black coatings based on the use of pulse and pulse reverse electrophoretic deposition. The low-reflectivity CNT coatings have been successfully deposited on a variety of geometries: flat coupons, curved surfaces, sharp edges, and internal and external surface of square tubes using the FARADAYIC® EPD process with different anode-cathode configurations (Figure 1 A). The CNT coatings show the total hemispherical reflection of 0.4% ~ 0.8% across visible to near infrared (NIR) wavebands (Figure 1 B). The CNT coatings withstood simulated launch conditions vibration tests, and no weight loss and optical degradation were observed. The atomic erosion resistance of the CNT coatings was evaluated in a simulated low earth orbit (LEO) environment. The CNT coatings showed enhanced resilience to LEO O-atom erosion when compared to Kapton and HOPG. The UV radiation effects on the coatings are under investigation.

The developed economic and scalable technology for producing CNT black coatings on desired substrates can not only be used for minimizing stray and reflected light for space-borne instruments, but also be beneficial for optoelectronic fields for minimizing unwanted surface reflections for solar thermal power generation and storage, solar-driven steam generation for sanitization and water purification, and so on.

Figure 1
(Invited) Logic-in-Memory Based on an Atomically Thin Semiconductor
Authors: Kis Andras
Published: July 2021

The growing importance of applications based on machine learning is driving the need to develop dedicated, energy-efficient electronic hardware. Compared with von-Neumann architectures, brain-inspired in-memory computing uses the same basic device structure for logic operations and data storage, thus promising to reduce the energy cost of data-centric computing significantly. Two-dimensional materials such as semiconducting MoS2 could stand out as a promising candidate to face this obstacle thanks to their exceptional electrical and mechanical properties. Here, we show that wafer-scale grown MoS2 can be used as an active channel material for developing logic-in-memory devices and circuits based on floating-gate field-effect transistors (FGFET). The conductance of our FGFETs can be precisely and continuously tuned, allowing us to use them as building blocks for reconfigurable logic circuits where logic operations can be directly performed using the memory elements. We show that this design can be simply extended to implement more complex programmable logic and functionally complete sets of functions. Our findings highlight the potential of atomically thin semiconductors for the development of next-generation low-power electronics.
(Invited) How to Use Acoustic Phonons to Enrich the Properties of a Cavity Coupled Nano-Emitter ?
Authors: Borel Antoine , Claude Théo , Jeantet Adrien , Lauret Js , Voisin Christophe , Chassagneux Yannick
Published: July 2021

Carbon nanotubes have emerged as original single photon source in the near IR and in the telecom bands. To further control their emission rate and directionality, individual carbon nanotube can be coupled to a high Q and small mode volume cavity (Purcell effect). Due to the 1D geometry of carbon nanotube, the coupling between localized exciton and acoustic phonon is particularly strong. This coupling can be used as an additional degree of freedom in cavity coupled single emitters; it brings a very rich physics involving non-markovian decoherence, tripartite coupling, and asymmetric energy exchange... In particular the coupling to phonon can be used to “force” the nanotube to emit preferentially at the cavity frequency rather than at its intrinsic transition frequency.. We implemented this approach to realize a widely tunable single photon source.

Jeantet et al, PRL 116, 247402 (2016)

Jeantet et al, Nano Lett. 17, 4184 (2017)

He et al , Nat. Mat. 17, 663 (2018)

Chassagneux et al PRB 97, 205124 (2018)
(Invited) Visualizing 2D Materials at the Atomic Scale
Authors: Luican-Mayer Adina
Published: July 2021

Understanding and controlling the properties of 2D materials to our advantage can be contemplated with the development of experimental tools to probe and manipulate electrons and their interactions at the atomic scale. In this talk, I will present scanning tunnelling microscopy and spectroscopy experiments aimed at: elucidating the nature of atomic-scale defects in 2D materials, visualizing moiré patterns between crystals with different symmetries and imaging surface and edge states in a magnetic topological system. Moreover, I will discuss how we leverage our expertise in probing and engineering electronic states at surfaces of 2D materials to further the development of graphene-based gas sensors and gated quantum dot circuits based on 2D semiconductors.

Figure 1
(Invited) Machine Learned Deep Neural Networks to Simulate Raman Spectrum of Defective Graphene Systems
Authors: Cote Michel , Malenfant-Thuot Olivier , Ryczko Kevin , Majumdar Arnab , Tamblyn Isaac
Published: July 2021

Raman spectrum is a common spectroscopic tool used in materials synthesis and characterization. The width and shift of Raman peaks are commonly used in characterization of graphene samples. In this presentation, I will highlight our efforts in using machine learned models to develop an efficient and accurate methodology for simulating accurate spectroscopic signatures in graphene. We are using deep neural networks trained with density functional theory calculations to take advantage of the accuracy of this approach while being able to simulate large atomic systems corresponding to doped graphene layers. We are then able to evaluate the empirical models presently used to assess the defect levels in graphene and compare them to state-of-the-art calculation on such systems.
(Invited) Graphene Aerogels: From Self-Assembly to Applications
Authors: Cerruti Marta
Published: July 2021

Graphene aerogels are highly porous and light structures that maintain most of the exceptional mechanical and electrical properties of graphene in a substrate that can be handled and used in practical applications. This is possible because the graphene flakes do not excessively restack during aerogel formation.

In this talk we will explore how we can direct the self-assembly of graphene oxide flakes to generate graphene aerogels with different structures and mechanical properties, ranging from plastic to elastic structures and structures with dual porosity and highly controlled architectures. We will briefly highlight applications for these structures in fields as varied as sensing, pollutant absorption, photocatalysis, and cell culture.
(Invited) Chemical Reactions of Ionic Metallofullerenes: An Alternative Route for Exohedral Functionalization
Authors: Hu Yajing , Li Fang-Fang Li
Published: July 2021

The chemistry of cationic forms of clusterfullerenes remain less explored than that of the corresponding neutral or anionic species. In the present work, M3N@Ih
-C80 (M = Sc or Lu) cations were generated by both electrochemical and chemical oxidation methods. The as-obtained cations successfully underwent the typical Bingel-Hirsch reaction that fails with neutral Sc3N@Ih
-C80. Two isomeric Sc3N@Ih
-C80 cation derivatives, [5,6]-open and [6,6]-open adducts, were synthesized, and the former has never been prepared via a Bingel-Hirsch reaction with neutral clusterfullerenes. Density functional theory (DFT) calculations indicated that the oxidized M3N@Ih
-C80 was much more reactive than the neutral compound upon addition of the diethyl bromomalonate anion. The Bingel-Hirsch reaction of M3N@Ih
-C80 cations occurred via an unusual outer-sphere single-electron transfer (SET) process from the diethyl bromomalonate anion to the stable intermediate [M3N@C80(C2H5COO)2CBr]•. Remarkably, the diethyl bromomalonate anion was found to act as both a nucleophile and an electron donor. Cationic forms of clusterfullerenes exhibited chemical properties that are different from those of the corresponding neutral and anionic forms. These findings promote a better understanding of EMFs cations and offer a complementary strategy to activate and functionalize EMFs.
(Invited) Actinide Cluster Fullerenes: Clusters and Actinide Bondings inside the Confined Space of Carbon Cage
Authors: Chen Ning , Echegoyen Luis , Zhuang Jiaxin , Yao Yangrong , Li Xiaomeng , Yang Wei
Published: July 2021

The hollow internal cavity of fullerene buckyballs has been known to be able to encapsulate novel metallic units, especially those otherwise very reactive or virtually impossible to prepare clusters. In this talk, we will present our recent studies of novel cluster endohedral fullerenes, focusing on their unique encapsulated clusters and bonding motifs. The synthesis and characterization of U2C@C80 gives an unprecedented look into a long sought after but heretofore unknown U=C bond which lacks heteroatom support, allowing for detailed structural and electronic insights.1 Novel actinide cluster fullerenes, U2C2@Ih
(7)-C80 and U2C2@D
3h
(5)-C78, were synthesized and fully characterized by mass spectrometry, single crystal X-ray crystallography, UV-vis-NIR , Raman spectroscopy, IR spectroscopy, as well as density functional and multireference wavefunction calculations. The encapsulated U2C2 is the first example of a uranium carbide cluster featuring two U centers bridged by a C≡C unit. The U-C bond distances in these U2C2 clusters are in the range between 2.130-2.421 Å. While the U2C2 cluster in U2C2@C80 adopts a butterfly-shaped geometry with a U-C2-U dihedral angle of 112.7°and a U-U distance of 3.855 Å, the U-U distance in U2C2@C78 is 4.164 Å and the resulting U-C2-U dihedral angle is increased to 149.1°. The combined experimental and quantum-chemical results suggest that the formal U oxidation state is +IV in the U2C2 cluster.
(Invited) Synthesis and Optical Properties of Graphene Nanoparticles
Authors: Medina Lopez Daniel , Liu Thomas , Rondin Loic , Lauret Js , Campidelli Stephane
Published: July 2021

In recent years, the scientific community has given much interest to graphene as a material because of its good mechanical, thermal and electrical properties. Nevertheless, the lack of a bandgap in graphene limits its optical and optoelectronic applications. To tackle this problem, size reduction, a popular technique for bandgap engineering, has been used. Thus, we shine our interest in graphene quantum dots (GQDs). GQDs synthesis has been mostly described via top-down methods (lithography, hydrothermal and electrochemical approaches).1 Though cheap and efficient, these methods do not allow for precise control of the size, shape and edges of the GQDs. This is where bottom-up approaches, especially the ones borrowing known reactions from organic chemistry, come in handy.2

Our group has previously reported single-photon emission from functionalized bottom-up synthesized GQDs.3 We wish to improve our understanding of GQDs optical properties. For this purpose, we have synthesized nanoparticles having the same number of hybridized sp2 carbons but arranged in different shapes (Figure 1). Besides modifying the optical properties, we also aim to improve the solubility of the GQDs by changing the functional groups at the edge of the nanoparticle. An improved solubility should simplify the study of individualized nanoparticles.

References :

[1] Yang, J.-S., Martinez, D. A. & Chiang, W.-H. Synthesis, Characterization and Applications of Graphene Quantum Dots in Recent Trends in Nanomaterials: Synthesis and Properties, Khan, Z. H., Springer Singapore, (2017).

[2] Müller, M., Kübel, C. & Müllen, K. Giant Polycyclic Aromatic Hydrocarbons. Chem. Eur. J.
4, 2099–2109 (1998).

[3] Zhao, S. et al. Single photon emission from graphene quantum dots at room temperature. Nat. Commun.
9, 1–5 (2018).

Figure 1
In-Situ Crossover Measurements for Vanadium-Based Non Aqueous Redox Flow Battery
Authors: Mushtaq Kashif , Mendes Adelio
Published: July 2021

The efficient operation of the non-aqueous redox flow battery (NAqRFB) requires a selective membrane that prevents the crossover of the charged storage molecules (redox species) to minimize self-discharge or mixed potentials; actually, the crossover-induced capacity loss remains one of the most challenging problems for NAqRFB. At the same time, the membrane must enable high ionic conductivity (ions from supporting electrolyte) to lower ohmic losses. The identification of a highly conductive, yet selective membrane is of paramount importance for market penetration of RFBs. Although the membrane should be extremely selective, for allowing years of continuous operation, the truth is that all commercially used membranes allow to some extent redox species permeation, especially when a thinner membrane is pursued to ensure high ionic conductivity. In terms of capacity retention, the reactant that crosses directly through the membrane is oxidized or reduced without providing electrical work, leading to lower efficiency. Therefore, crossover in a NAqRFB and its impact on cell operation is a critical phenomenon that needs to be quantified and mitigated in the development of redox flow-cells.

The crossover through the membrane is problematic since it leads to loss of capacity and self-discharge. An in-situ electrochemical method based on linear sweep voltammetry was introduced to determine crossover through different membranes. The results were further confirmed through the permeance of redox ion using an ex-situ method, performance characterization, and by measuring the overpotentials. Ferrocene is reported as a model probing species for in-situ crossover measurement. The cation exchange membrane having a higher thickness (Nafion 117) and anion exchange membrane having reinforcement (FAPQ-375-PP) performed better. The model redox species (vanadium acetylacetonate) were used for the performance assessment of NARFB. The columbic efficiency was 91.47 % and voltaic efficiency of 72.9 %. The ohmic and mass transport overpotentials affecting the performance of NARFB were 0.46 V and 1.44 V. This in-situ technique will allow researchers to account for the contribution of migration-driven crossover influenced by the applied electrical field and not only the diffusion-based crossover as reported in the previous studies. Since there is no need for disassembling of the cell, so it can be used as a diagnostic tool to assess the realistic membrane situation under actual working conditions. The quantification of the permeance directly from the flow-cells and overpotentials complements the improvement in the designing and toward further optimization of the operational parameters. Due to its convenience and practicability, this technique has the potential to become the basic testing method to determine crossover and aid in membrane selection for many electrochemical cells/systems. This work is still in progress for in-depth study covering other aspects as well.

Figure 1
Why Two-Dimensional Semiconductors Generally Have Low Electron Mobility
Authors: Cheng Long , Zhang Chenmu , Liu Yuanyue
Published: July 2021

Atomically thin (two-dimensional, 2D) semiconductors have shown great potential as the fundamental building blocks for next-generation electronics. However, all the 2D semiconductors that have been experimentally made so far have room-temperature electron mobility lower than that of bulk silicon, which is not understood. Here, by using first-principles calculations and reformulating the transport equations to isolate and quantify contributions of different mobility-determining factors, we show that the universally low mobility of 2D semiconductors originates from the high “density of scatterings,” which is intrinsic to the 2D material with a parabolic electron band. The density of scatterings characterizes the density of phonons that can interact with the electrons and can be fully determined from the electron and phonon band structures without knowledge of electron-phonon coupling strength. Our work reveals the underlying physics limiting the electron mobility of 2D semiconductors and offers a descriptor to quickly assess the mobility [1,2,3].

[1] L. Cheng, C. Zhang, Y. Liu, Phys. Rev. Lett., 2020, DOI: 10.1103/PhysRevLett.125.177701

[2] L. Cheng, C. Zhang, Y. Liu, J. Am. Chem. Soc., 2019, DOI: 10.1021/jacs.9b05923

[3] L. Cheng, Y. Liu, J. Am. Chem. Soc., 2018, 140, 17895-17900
Tailoring Interlayer Excitons in 2D Van Der Waals Heterostructures with Molecular Functionalization
Authors: Ji Jaehoon , Houpt Duncan , Choi Jong Hyun
Published: July 2021

Two-dimensional (2D) van der Waals (vdW) heterostructures from transition metal dichalcogenide (TMDC) semiconductors offer a new class of interlayer excitons with promising optoelectronic properties for the next-generation optoelectronics such as excitonic devices and spintronics. To realize such applications, the unique properties of interlayer excitons must be thoroughly understood and precisely controlled. This work introduces a new strategy to selectively modulate interlayer excitons by functionalizing organic chromophore molecules. We explored two dye molecules, tetracyanoquinodimethane (TCNQ) and eosin Y (EY), and deposited their uniform layers on vdW heterostructures from MoS2 and WSe2 monolayers. We demonstrate that photoinduced charge transfer between MoS2 and WSe2 may be promoted or suppressed by the organic layers, thus affecting the photoluminescence (PL) emissions. Kelvin probe force microscopy (KPFM) shows that dark-state doping may also affect the interlayer excitons, yet we find that photoinduced charge transfer plays a dominant role. Our results elucidate interlayer excitons at the heterointerfaces and lay the foundation for diverse optoelectronic applications.
(Invited) Integration of 2D Materials in Van Der Waals Photonic Heterostructures
Authors: Ignatova Tetyana , Pourianejad Sajedeh , Rotkin Slava V.
Published: July 2021

Recently, significant attention has been focused at photonic properties of vertical heterostructures of two-dimensional (2D) materials which is driven by large range of their applications in sensing and information technology. In this work, the Van der Waals heterostructures were produced by integration of CVD grown 2D MoS2 with transferred monolayer graphene. Each of 2D layers possesses its own surface electromagnetic (optical) modes. While in the photonic heterostructure these modes are strongly coupled. Scattering-type scanning near-field optical microscopy allows to visualize 2D surface polaritons, as well as their hybridization with the resonances of the bulk substrate polaritons. Using excitation frequencies well below substrate resonances, a signature of charge transfer in van der Waals heterostructures with nanometer resolution was obtained.

Acknowledgement: Authors acknowledge the JSNN, a member of the Southeastern Nanotechnology Infrastructure Corridor (SENIC) and National Nanotechnology Coordinated Infrastructure (NNCI), supported by the NSF (ECCS-1542174), The PSU Two-Dimensional Crystal Consortium – Materials Innovation Platform 2DCC-MIP, supported by NSF cooperative agreement (DMR-1539916). S.V.R. acknowledges PSU MRSEC supported by NSF (DMR-2011839). Authors are grateful to Dr. S. Aravamudhan (JSNN) and Dr. J. Redwing (2DCC-MIP).
(Invited) Additively Manufactured Graphene Aerogel Supercapacitors
Authors: Beck Victor A , Chandrasekaran Swetha , Salazar de Troya Miguel , Lin Dun , Reale Batista Mariana Desiree , Yao Bin , Moran Bryan , Zhu Cheng , Duoss Eric B , Stadermann Michael , Tortorelli Daniel , Li Yat , Worsley Marcus Andre
Published: July 2021

Electrochemical energy storage (EES) and conversion devices (e.g. batteries, supercapacitors, and reactors) are emerging as primary methods for global efforts to shift energy dependence from limited fossil fuels towards sustainable and renewable resources. These electric-based devices, while showing great potential for meeting some key metrics set by conventional technologies, still face significant limitations. For example, an EES device tends to exhibit large energy density (e.g. lithium-ion battery) or power density (e.g. supercapacitor), but not both. This inability of a single device to simultaneously achieve both metrics represents a major obstacle to widespread adoption of EES devices. Improvements in materials, such as the integration of 2D materials (e.g. graphene, dichalcogenides, MXene, etc.) into electrochemical devices has yielded some exciting results towards tackling this issue, but significant improvements are still needed. Our approach to simultaneously achieving high energy and power density is to focus on one of the fundamental processes that occur in these systems: mass (or charge) transport. The efficient transport of ions within EES devices is critical to realizing both large power and energy densities. The pore structure of the electrode is a key factor in determining this transport phenomena, but in many cases, engineering the pore structure in a highly deterministic fashion is not pursued or even possible for many electrode materials. In this work, we explore a number of additive manufacturing methods (e.g. direct ink write, projection microstereolithography, etc.) to engineer the pore structure of device electrodes. We also determine effective electrode geometries using both simple theory and topology optimization techniques. The topology optimization couples the solution of the forward electrochemical problem over the full electrode domain with gradient-based optimization. The output of our code is a three-dimensional CAD representation which optimizes over specific performance metrics and which can be used to print functional electrodes. This work provides a systematic path toward automatic design and fabrication of engineered electrodes with precise control over the fluid and species distribution.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Volume Expansion Induced Stresses in Ge Electrode Due Electrochemical Cycling Against Sodium
Authors: Pakhare Akshay , Nadimpalli Siva
Published: July 2021

Li-ion battery has been widely used due to its high energy and power density. However, due to scarcity of Li reserves there has been increased focus on Li-ion alternatives. One of the promising alternatives is Na-ion battery (NIB). However, NIB also suffers from similar degradation phenomena’s as Li-ion when cycled with large volume expansion anodes like Ge. Electrodes undergoing large volume expansion are subjected to significant amount of stress during electrochemical cycling process which causes mechanical degradation and capacity fade. Here, we measured volume expansion and the associated stresses in Ge thin film electrodes during sodiation/desoadiaiton cycling. In spite of the bigger size, Na-ion generated lower stresses in Ge during cycling as compared to Li-ion. The mechanical dissipation losses were observed to be comparable to other polarization losses in the Na-ion cell.
(Invited) Lead-Free Halide Perovskites for Hydrogen Evolution
Authors: Listorti Andrea
Published: July 2021

Metal halide perovskites (MHPs) semiconductors possess unique optical properties, such as high optical absorption in the visible region, tunable band-gap and long carrier lifetime, which have been extensively exploited in photovoltaics and optoelectronic applications.[1] More recently there has been a growing interests towards novel applications of MHPs, in particular in the field of solar-driven photocatalysis.[2] However, some of the most interesting photocatalytic reactions such as H2O splitting, CO2 and N2 reduction, dye degradation, require the use of water or alternative polar solvents, this represent a conundrum foreseeing MHPs utilization. In this talk we report clear evidence of water stability for two lead-free metal halide perovskites, namely dimethylammonium (DMA) DMASnBr3 and phenylethylammonium (PEA) PEA2SnBr4 obtained by means of diffraction, optical and x-ray photoelectron spectroscopy. The water stability for the 2D material is somehow expected due to the water-repulsive nature of the symmetry breaking organic cation, some computational work is addressing such improved water stability, showing also that the same mechanism is thought to protect tin from +2 to +4 oxidation. The stability in water of the 3D analogous represent instead an important innovation of the field. Such unprecedented water-stability has been applied to promote photocatalysis in aqueous medium, in particular by devising a novel composite material by coupling DMASnBr3 to g-C3N4, taking advantage from the combination of their optimal photophysical properties. The prepared composites provide an impressive hydrogen evolution rate >1700 μmol g-1 h-1 generated by the synergistic activity of the two composite constituents. DFT calculations provide insight into this enhancement deriving it from the favorable alignment of interfacial energy levels of DMASnBr3 and g-C3N4. The demonstration of an efficient photocatalytic activity for lead-free metal halide perovskites in water paves the way to a new class of light-driven catalysts working in aqueous environments.

References

[1] S. D. Stanks, H. L. Snaith, Nature Nanotec. 2015, 10, 931-402.

[2] H. Huang, B. Pradhan, J. Hofkens, M. B. Roeffaers, J. A. Steele, ACS Energy Letters 2020,

5, 1107-1123.

[3] L. Romani, A. Bala, V.Kumar, A. Speltini, A. Milella, F. Fracassi, A. Listorti, A. Profumo, L.Malavasi. Journal of Materials Chemistry C, 2020, 8, 9189-9194

[4] L. Malavasi, L. Romani, A. Speltini, F. Ambrosio, E. Mosconi, A. Profumo, S. Margadonna, A. Milella, F. Fracassi, A. Listorti, F. De Angelis and M. Marelli. (2020), Angew. Chem. Int. Ed.. Accepted Author Manuscript. https://doi.org/10.1002/anie.202007584

Figure 1
Surface Chemistry Matters: How Ligands Influence Excited State Interactions between CsPbBr3 and Methyl Viologen
Authors: DuBose Jeffrey , Kamat Prashant V
Published: July 2021

The photocatalytic properties of cesium lead bromide (CsPbBr3) perovskite nanocrystals make them attractive for designing light harvesting assemblies. Often ignored, the surface chemistry can dictate the excited state interactions of these semiconductor nanocrystals with charge-shuttling redox molecules. We have now explored the impact of CsPbBr3 nanocrystal surface modification on the excited state interactions with methyl viologen (MV2+) for three different ligand environments: prototypical oleic acid/oleylamine (OA/OAm) ligands, PbSO4-oleate capping, and didodecyldimethylammonium bromide (DDAB) ligands. Native OA/OAm ligands and PbSO4-oleate capping exhibit the strongest complexation with MV2+, whereas the bulky DDAB ligand environment shows an order of magnitude weaker complexation. The electron transfer rate constants as measured from transient absorption spectroscopy vary in the range of 1.2–3.6 × 1011 s–1 for different ligand environments. For DDAB-CsPbBr3 NCs, the efficiency of electron transfer (Φet) is 73%. Despite a protective capping layer, PbSO4-oleate capped CsPbBr3 maintains a redox-active surface which is viable for photocatalytic applications. These results highlight the impact of surface chemistry on excited state interactions of CsPbBr3 NCs and photocatalytic applications.

Figure 1
Combinatorial Development of LSF Based Cathode Material for IT-SOFC
Authors: Kılıç Fahrettin , Öztürk Tayfur
Published: July 2021

The primary challenges for the commercialization of the technology are considered to be costs and durability. To accommodate this, research is pushing towards lower cell operation temperature (intermediate temperature SOFC, IT-SOFC) in the range of 500–700 0C [1,2]. The lower temperatures involve advantages such as wider and cheaper choice of materials (e.g. metals), increased material durability, and increased system stability.

The progress in this field is, inevitably associated with a continuous search for novel cathode and anode materials having superior electrocatalytic activity in the intermediate-temperature range. These developments have also a key importance for other solid-state electrochemical devices, such as electrolyzer of carbon dioxide and water vapor [3].

The fact that oxygen reduction rate is faster at the interface ,necessitates cathodes to be considered as composite. In this context, the traditional method is to mix cathode with electrolyte. This approach allows oxygen to be reduced at the interface and transported at the same time. Mixing cathode with electrolyte allows us to adjust the thermal expansion coefficient of the cathode. Another benefit of this approach is better bonding between the cathode and the electrolyte.

Experimental

The aim is to find the best cathode composition as a mixture of (La0.5Sr0.5)MnO3-δ (LSM), (La0.8Sr0.2)FeO3-δ (LSF) and (Zr10.92Sc0.08)O2- δ (8ScSZ) for IT-SOFC. In this study LSM, LSF and ScSZ targets were sputtered on both sides of Zr10.92Sc0.08 O2- δ electrolyte to form symmetric cells. We obtained 21 cells at the same time each with a different cathode composition. Geometry of targets and substrate is given in figure 1.

Figure 1.Target and substrate geometries

The produced cells were structurally characterized with XRD and SEM. Electrochemical performance of cells were determined using electrochemical impedance spectroscopy. The target working temperature is 600 0C and area specific resistance is maximum 0.15 ohm.cm2.

References

[1] R. Knibbe, J. Hjelm, M. Menon, N. Pryds, M. Søgaard, H.J. Wang, K. Neufeld, J. Am. Ceram. Soc. 93 (9) (2010) 2877–2883.

[2] M.C. Tucker, J. Power Sources 195 (15) (2010) 4570–4582.

[3] Tsipis, E. V., & Kharton, V. V. (2007). Journal of Solid State Electrochemistry,12(9), 1039-1060.

Acknowledgement

The support was provided by the Scientific and Technological Research Council of Turkey (TUBITAK) with a project number 217M628, which the authors gratefully acknowledge.

Figure 1
Electrochemical Control of Dye Molecule Excitation Strongly Coupled with Plasmonic Surface Lattice Resonance
Authors: Murakoshi Kei , Minamimoto Hiro , Hayashi Takahiro
Published: July 2021

Metal nanoparticle array shows surface lattice plasmon mode which can confine the light energy into the 2-dimensional space. Effective utilization of light energy could be realized if molecule excitons are strongly coupled with plasmons in the structures. When the energy level of molecules located near the metal nanoparticles are close to that of plasmon, the strong coupling forms, resulting in the new energy state formation. In this study, we have controlled the coupling strength between Au lattice structure and organic dye molecules via electrochemical method.
(Invited) Structural Analysis of Organic Semiconducting Materials Using Solid-State NMR
Authors: Suzuki Katsuaki , Kaji Hironori
Published: July 2021

Our research group is currently conducting basic research on organic light-emitting diodes (OLEDs). Recently, we have successfully developed a series of blue and green TADF emitters for OLEDs realizing high external quantum efficiencies through high-throughput screening based on quantum chemical calculations. However, even using highly efficient emitting materials, the device performance depends on the device structure and aggregated state of organic molecules in the device. To understand the origin of the device performance, both theoretical and experimental approaches are important. In this regards, we have also carried out multiscale simulations and solid-state NMR (ssNMR) analysis of organic amorphous thin films. The ssNMR is the powerful technique for the detailed experimental analysis of amorphous aggregated materials, which has been difficult by typical diffraction methods because organic molecules in OLEDs are in the amorphous state. In this presentation, we demonstrate the structural analysis of organic semiconducting materials using ssNMR. Also, we we show the analysis of molecular orientation of an organic semiconducting material in an amorphous thin film state using DNP-ssNMR, which is one of the most powerful sensitivity enhancement technique of NMR.

Reference

(1) “Analysis of Molecular Orientation in Organic Semiconducting Thin Films Using Static Dynamic Nuclear Polarization Enhanced Solid-State NMR Spectroscopy”, Suzuki, K.; Kubo, S.; Aussenac, F.; Engelke, F.; Fukushima, T.; Kaji, H. Angew. Chem. Int. Ed. 2017, 56, 14842.

(2) “Solution-processable thermally activated delayed fluorescence emitters for application in organic light emitting diodes”, Suzuki, K.; Adachi, C.; Kaji, H. J. Soc. Inf. Disp.
2017, 25, 480.

(3) “Combined Inter- and Intramolecular Charge-Transfer Processes for Highly Efficient Fluorescent Organic Light-Emitting Diodes with Reduced Triplet Exciton Quenching”, Moon, C.-K.; Suzuki, K.; Shizu, K.; Adachi, C.; Kaji, H.; Kim, J.-J. Adv. Mater.
2017, 131, 6614.

(4) “Triarylboron-based Fluorescent Organic Light-emitting Diodes with External Quantum Efficiencies Exceeding 20%”, Suzuki, K.; Kubo, S.; Shizu, K.; Fukushima, T.; Wakamiya, A.; Murata, Y.; Adachi, C.; Kaji, H.; Angew. Chem. Int. Ed. 2015, 54, 15231.

(5) “Purely organic electroluminescent material realizing 100% conversion from electricity to light”, Kaji, H.; Suzuki, H.; Fukushima, T.; Shizu, K.; Suzuki, K.; Kubo, S.; Komino, T.; Oiwa, H.; Suzuki, F.; Wakamiya, A.; Murata, Y.; Adachi, C. Nat. Commun. 2015, 6, 8476.
(Invited) Tetracene Molecular Architectures for High-Yield and Long-Lived Individual Triplet States through Singlet Fission
Authors: Hasobe Taku , Sakai Hayato , Kobori Yasuhiro , Tkachenko Nikolai
Published: July 2021

Singlet fission (SF) is a multi-exciton generation process in two neighboring organic chromophores (S1 + S0) where two individual triplet excitons (T1 + T1) are generated from one-photon absorption through a correlated triplet pair (TT). Therefore, SF is highly promising for construction of next-generation solar energy conversion systems such as photovoltaics and photocatalysis. In addition to the close interaction of two nearby molecules, energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)] are required. Acene derivatives such as pentacene and tetracene satisfy the above condition. However, the number of high-yield and long-lived triplet excited states through SF using tetracene derivatives is extremely limited because of the acceleration of the reverse reaction: triplet-triplet annihilation. Namely, the precise structural control of orientation and distance between two nearby tetracene units is definitely required for long-lived individual triplets through SF. In this presentation, we mainly focus on the tetracene molecular assemblies for high-yield and long-lived individual triplet states through SF using a series of covalently-linked dimers1 and tetracene-modified gold nanoclusters.2

References

Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett.
2019, 4, 26-31.

Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Chem. Soc.
2019, 141, 14720-14727.
(Invited) Synthesis and Optical Properties of Core-Shell Swnt Hybrids
Authors: Orcin-Chaix Lucile , Hanana Manel , Rondin Loic , Bretenaker Fabien , Chassagneux Yannick , Voisin Christophe , Lauret Js , Campidelli Stephane
Published: July 2021

Because of their emission in the near infrared region, Single-Walled Carbon Nanotubes remain among the most attractive nanomaterials for (opto)electronics, optics and photonics.1
-
3 However, the extreme sensitivity of nanotubes to their environment hinders their applications. Thus, the fabrication of tailor-made functional hybrid materials that preserve the optical properties of SWNTs and facilitate their manipulation is extremely important. One route to take advantage of the protection offered by polymers is to synthesize core/shell nanostructures in which the nanotube is the active core and the polymer, tightly bound to the nanotubes, acts as a protective shell.

Here, we describe the synthesis of core-shell nanotube materials made of SWNTs and polystyrene. We developed a two-step strategy that permits to form a stable and homogeneous layer of polymer around the nanotubes by adding first polystyrene via the micelle swelling method and then by locking the structure via radical polymerisation in micelles of styrene and divinylbenzene. After polymerisation and redispersion, the nanotube hybrids can be easily manipulated in solution; they still exhibited photoluminescence properties both in solution and in the solid state demonstrating that the SWNTs embedded in their polystyrene shell are isolated one from each other.4
,5

References

Avouris, P.; Freitag, M.; Perebeinos, V. Nat. Photonics
2008,
2, 341-350.

Godin, A. G.; Varela, J. A.; Gao, Z.; Danné, N.; Dupuis, J. P.; Lounis, B.; Groc, L.; Cognet, L. Nat. Nanotechnol.
2017,
12, 238-243.

He, X.; Htoon, H.; Doorn, S. K.; Pernice, W. H. P.; Pyatkov, F.; Krupke, R.; Jeantet, A.; Chassagneux, Y.; Voisin, C. Nat. Mater.
2018,
17, 663-670.

Orcin-Chaix, L.; Trippé-Allard, G.; Voisin, C.; Okuno, H.; Derycke, V.; Lauret, J.-S.; Campidelli, S. J. Mater. Chem. C
2018,
6, 4786-4792.

Orcin-Chaix, L.; Campidelli, S.; Rondin, L.; Fossard, F.; Bretenaker, F.; Chassagneux, Y.; Voisin, C.; Lauret, J.-S. ACS Appl. Nano Mater.
2020,
3, 7291-7296

Figure 1
Power-Generating Electrochemical Anion Exchange CO2 Separator for Practical AEMFC Application
Authors: Zheng Yiwei , Mustain William
Published: July 2021

Anion exchange membrane fuel cells (AEMFCs) have been widely touted as a low- cost alternative to existing proton exchange membrane fuel cells. However, one of the limitations of this technology has been the severe performance penalty related to the introduction of CO2 to the cell (typically from air in the cathode feed). A low cost, low energy solution is needed that is able to remove CO2 from the incoming air before it is fed to the AEMFC system.1,2 Many approaches to removing CO2 from the cathode inlet would consume valuable energy and complicate the systems-level balance-of-plant. However, recently3, an electrochemical approach was proposed that i) is able to generate power; and ii) takes advantage of the carbonation phenomena that harms AEMFCs. Such a device can be called an anion exchange CO2 separator (AECS).

An AECS operates on the same principles as an AEMFC. H2 is fed to the anode and O2/air is fed to the cathode. As OH- is formed from the oxygen reduction reaction at the cathode, it is converted to carbonates by reaction with carbon dioxide. The carbonates are transported to the anode by migration where they are eventually released as CO2. Ideally, an AECS operates on waste H2 and a high concentration CO2 stream leaves the anode and an air stream devoid of CO2 leaves the cathode. By design, the AECS is smaller than the primary AEMFC. Because carbonates are present, the AECS operates at a lower power density than the AEMFC, but the method has the promise to use waste to generate energy while removing CO2.

In this work, the effectiveness of an AECS in lowering the CO2 concentration of an incoming stream of 400ppm air is investigated. Several parameters are changed, including the AECS active area and anode flowrate. The primary focus of these experiments was to develop operating conditions that lead to very low ppm CO2 concentrations leaving the AECS cathode. In addition to showing significant CO2 removal, we also show an AECS that operates with a stable output for over 150 h. Finally, AEMFC operation on AECS-purified industrial air is successfully demonstrated.

References

Zheng, T. J. Omasta, X. Peng, L. Wang, J. R. Varcoe, S. Pivovar, and W. E. Mustain, Energy Environ. Sci., 12, 2806–2819 (2019).

R. Gerhardt, L. M. Pant, H.-S. Shiau, and A. Z. Weber, ECS Trans., 86, 15–24 (2018).

Yan, B. Setzler, Y. Zhao, M. S. R. Carbonell, and S. Gottesfeld, U.S. Patent No. 10,811,711. 20 Oct. 2020.
Preparation of Liquid Crystalline Subnaphthalocyanines As Optoelectronic Materials
Authors: Mizutani Tadashi
Published: July 2021

Chloroboron(III) hexachloro- hexabromo-, and hexaiodosubnaphthalocyanines were prepared by cyclotrimerization of 6,7-dihalo-2,3-naphthalenedicarbonitrile in the presence of BCl3, They were converted to fluoroboron(III) hexahalosubnaphthalocyanine by the reaction with AgBF4. Their solubility, electronic absorption spectroscopy, fluorescence emission spectroscopy and HOMO/LUMO energy levels were evaluated. Fluorescence quantum yields of chloroboron(III) hexafluoro-, hexachloro-, hexabromo-, and hexaiodosubnaphthalocyanine were 0.22, 0.20, 0.11, 0.05, respectively, indicating that heavy atom effects of Br and I were effectively deactivate the singlet excited states. These subnaphthalocyanines showed lower HOMO/LUMO energies than the parent subnaphthalocyanine by 0.13 – 0.39 eV. The optical band gap decreased in the order: hexafluoro- > hexachloro- > unsubstituted > hexaiodo-subnaphthalocyanine. Hexaiodosubnaphthalocyanines were converted to chloroboron(III) and fluoroboron(III) hexa(1-alkynyl)- and hexa(2-arylethynyl)subnaphthalo-cyanines by Sonogashira coupling of hexaiodosubnaphthalocyanines with substituted acetylenes. Introduction of butyl or longer alkyl groups via ethynylene linkages on the periphery resulted in lower melting points, and higher solubility in dichloromethane. X-ray diffraction (XRD) patterns of the cast film indicated that hexa(2-(4-hexylphenyl)ethynyl)- and hexa(2-(4-hexyloxyphenyl)ethynyl)subnaphthalocyanines with a B-F bond are packed in a discotic hexagonal columnar phase with lattice constants a = 59-64 Å and stacking distance c = 4.7-4.8 Å. The Q-band in visible spectra of the thin film of these B-F derivatives was blue-shifted, supporting the formation of H-aggregate in stacked columns. Polarized optical microscope showed that these subnaphthalocyanines with a B-F bond exhibited mesophase at 180oC. XRD of these subnaphthalocyanines at 180 oC confirms a two dimensional hexagonal phase. XRD of the corresponding derivatives with a B-Cl bond showed that they were either amorphous or less crystalline.

Figure 1
Porphyrinoids for Photodynamic Therapy (PDT) and Antimicrobial PDT
Authors: Torres Tomas , Paramio Irene , Fonseca Alba , Lahoz Maria , Dominguez Ana Belen , Rahali Asma , Duran-Sampedro Gonzalo , Garcia-Iglesias Miguel , De La Torre Gema , Rodriguez-Morgade M. Salome
Published: July 2021

Photodynamic therapy combines light, molecular oxygen and a PS for the production of reactive oxygen species (ROS), such as singlet oxygen (1O2) and free radicals, leading to oxidative stress and eventual cell death. Phthalocyanines (Pcs) fulfil many of the requirements to be applied as photosensitizers for singlet oxygen generation. However, a major drawback of these compounds is their low solubility in physiological media. Functionalization of the macrocycle at the peripheral and/or axial positions with appropriate hydrophilic functions provides compounds with an enhanced solubility in water. In this respect, several strategies have been adopted to increase the hydrophilicity of Pcs and make them more bio-compatible, like their functionalization with charged groups, aminoacids or carbohydrates, or conjugation to appropriate nanocarriers. The introduction of such entities at Pc axial positions reduces the aggregation of the macrocycles in solution, thus improving their 1O2generation efficiency. For recent work of our group, see references 1 and 2, and articles cited therein.

1V. Almeida-Marrero, E. van de Winckel, E. Anaya-Plaza, T. Torres, A de la Escosura, “Porphyrinoid biohybrid materials as an emerging toolbox for biomedical light management“, Chem. Soc. Rev., 2018; 47: 7369-7400.

2 P.-C. Lo, M. S. Rodríguez-Morgade, R. K. Pandey, D. K. P. Ng, T. Torres, F. Dumoulin, "The unique features and promises of phthalocyanines as advanced photosensitisers for photodynamic therapy of cancer", Chem. Soc. Rev. 2020; 49: 1041-1056
Recent Advances in Zinc Anc Cooper Phthalocyanines As Hole Transporting Materials in Perovskite Solar Cells
Authors: Sastre-Santos Angela
Published: July 2021

Recently, significant progresses have been achieved in the fabrication of highly efficient perovskite solar cells, while major challenges, such as commercial viablity of exotic materials and their instability, remain as an obstacle. Hole transporting materials (HTMs) represent a tricky choice for the fabrication of efficient solar cells and the cost uneffective Spiro-OMeTAD continue to be so far the most obvious candidate. Semiconductors molecules, such as metallophthalocyanines (MPcs)1 appeared as a promising class of p-type material, since they are less expensive and more stable.

In this communication, we will present the synthesis of novel ZnPcs,2 ZnPc dimers3 and CuPcs4 (see as examples Figure 1) as efficient, stable, and low cost HTMs in PSCs. The MPcs are substituted with functional groups that possesses a very good solubility in a wide range of organic solvents, adequate HOMO LUMO levels and thus can be applied from solution processing in a wide range of perovskite solar cell devices.

Figure 1. Different ZnPcs structures as HTMs in PSCs

References

M. Urbani, M. E. Ragoussi, M. K. Nazeeruddin, T. Torres, Coord. Chem. Rev.
2019, 381, 1-64.

P. Huang, A. Hernández, S. Kazim, J. Ortíz, Á. Sastre-Santos, S. Ahmad Sustainable Energy &Fuels.
2020, 4, 6188-6195.

a) D. Molina, M. A. Ruiz-Preciado, F. Sadegh, M. João Álvaro-Martins, M. Grätzel, A. Hagfeldt, Á. Sastre-Santos, J. Porphyr. Phthalocyanines, 2019, 23, 546–553. b) D. Molina, M. A. Ruiz‐Preciado, B. Carlsen, F. T. Eickemeyer, B. Yang, N. Flores‐Díaz, M. J. Álvaro‐Martins, K. Nonomura, A. Hagfeldt and Á. Sastre‐Santos, ChemPhotoChem, 2020, 4, 307–314.

a) L. Caliò, J. Follana-Berná, S. Kazim, M. Madsen, H. G. Rubahn, Á. Sastre-Santos, S. Ahmad, Sustainable Energy Fuels, 2017, 1, 2071-2077. b) P. Huang, A. Hernández, J. Follana-Berná, S. Kazim, J. Ortíz, Á. Sastre-Santos, S. Ahmad, submitted.