bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-Time Near-Infrared Confocal Imaging of Bacterial Cell Division in the Presence of Single-Walled Carbon Nanotubes
Authors: Antonucci Alessandra , Schuergers Nils , Zubkovs Vitalijs , Boghossian Ardemis Anoush
Published: February 2020

The chemical and optical properties of single-walled carbon nanotubes (SWCNTs) have inspired the development of a plethora of different applications in the field of cell nanobiotechnology. However, most studies to date have focused on interfacing SWCNTs with cells of eukaryotic organisms. The work herein presented introduces a first comprehensive study focusing on the interaction of fluorescent SWCNTs with bacterial cells. We established wrappings that facilitate nanoparticle uptake over the bacterial cell wall, which represents a first important step towards the expansion of nanomaterials’ application in the broad field of microbiology. We employed a custom-built, spinning disc confocal microscope to image near-infrared (NIR) SWCNT fluorescence within the cells. By performing in situ cell growth and nanoparticle tracking we investigated the fate of internalized SWCNTs upon multiple cell division events. Real-time monitoring of cell growth revealed that the indefinitely photostable NIR fluorescence is inherited by daughter cells. The imparted NIR fluorescence thus offers an unprecedented avenue for quantitative and continuous imaging of nanobioengineered cells across multiple generations. Above and beyond bacterial nanobionics, this technique creates new opportunities for imaging subcellular targeting and trafficking of NIR-fluorescent probes in the field of drug delivery and biosensing.
Biomolecular Sensors Based on Microfluidics-Embedded Graphene Field-Effect Transistors
Authors: Bouilly Delphine , Bazan Claudia Marcela , Sauvage Madline , Bencherif Amira
Published: February 2020

With the rapid pace of discovery of molecular biomarkers associated with cancer and other diseases, there is a need for bioanalytical techniques able to detect and quantify large panels of biomolecules, with high throughput and accuracy. Nanoelectronic sensors are emerging in this field due to their potential for improved sensitivity, parallelization and portability. In this presentation, I will introduce our recent progress in assembling nanoelectronic biomolecular sensors based on graphene field-effect transistor device arrays combined with microfluidic circuitry. In particular, I will present two designs targeting either DNA oligonucleotide sequences or antibody-antigen coupling, and I will describe their electrical signatures for specific and non-specific biomolecular interactions with the graphene material. Finally, I will discuss the electronic detection of breast cancer and leukemia biomarkers for clinical diagnostics applications.
(Invited) Development and Utilization of an in Vitro Single Walled Carbon Nanotube System to Quantify Extracellular Nitric Oxide Concentration
Authors: Iverson Nicole M , Stapleton Joseph A , Glas Jessica , Hofferber Eric M
Published: February 2020

Nitric oxide (NO) is an important biological signaling factor, but due to its fast degradation rate quantification is difficult. Single walled carbon nanotube sensors for NO are unique in their ability to quantify NO concentrations in vitro over extended time periods without genetically altering the cells of interest. Since nanotubes are so small they are readily taken up by cells. To investigate just the extracellular concentration of nitric oxide, avoiding detection of the intracellular concentration, we developed a system to look at extracellular nitric oxide concentrations for in vitro samples. This new system allows for seeding adherent cells in desired patterns without altering the nanotube sensors, therefore allowing spatial and temporal detection of NO in regions between cell islands or associated with multiple cell types. The system is robust enough to allow for other nanotube sensors to be used with alternate cell types, creating a technique to quantify multiple analytes that are excreted from cells in a temporal and spatial fashion.
(Invited) Controlling the Inner Dielectric Environment of Carbon Nanotubes to Tune Their Optical Properties
Authors: Cambre Sofie , Campo Jochen , Botka Bea , van Werveke Wouter , Obrzut Jan , Wenseleers Wim , Fagan Jeffrey A.
Published: February 2020

The optical properties of single-wall carbon nanotubes (SWCNTs) are extremely sensitive to their external and internal environment. For example, filling the endohedral cavity with water molecules results in characteristic shifts and broadening of both the SWCNTs’ radial breathing mode vibrational frequency and their optical (electronic) transitions, as well as a quenching of their emission.[1] Although mostly ignored in literature, solvent ingestion effects are substantial, and can also be used to passivate the nanotube interior, by controlled manipulation of the endohedral environment prior to dispersion.[2]

In this work, specific and tunable modification of the optical properties of SWCNTs is demonstrated through the direct encapsulation of guest molecules with widely varying dielectric constants. Over 30 different compounds with varying static dielectric constant have been encapsulated inside the SWCNTs and their spectroscopic analysis, in comparison to unfilled (empty) SWCNTs, demonstrates experimentally that the general effect of filler static dielectric constant on the SWCNTs’ optical properties corresponds to a monotonic energy reduction (red-shifting) of the optical transitions with increased magnitude for higher dielectric constants. In addition to these spectral shifts, the filling also reveals a general increase of fluorescence intensity with lower dielectric constants.

Our investigation hence demonstrates a new degree of modulation of the SWCNTs’ optical properties by simple endohedral ingestion of various guest molecules.

[1] S. Cambré et al. Phys. Rev. Lett. 104, 207401 (2010); W. Wenseleers et al. Adv. Mater. 19, 2274 (2007); S. Cambré et al. ACS Nano 6, 2649 (2012)

[2] J. Campo et al Nanoscale Horizons 1, 317 (2016)
Fast Photo-Chemical Synthesis of Fluorescent Defects on Carbon Nanotubes
Authors: Lin Ching-Wei , Bachilo Sergei M. , Zheng Yu , Tsedev Uyanga , Huang Shengnan , Weisman R. Bruce , Belcher Angela M.
Published: February 2020

Solitary fluorescent defects on single-walled carbon nanotubes (SWCNTs) have been shown to emit short-wave infrared (SWIR) single photons at room-temperature, enabling applications for quantum communication or cryptography. In addition, the new emission band at lower energy allows better resolution and contrast of in vivo images because lower scattering and lower autofluorescence can be achieved by shifting both excitation and emission into SWIR. A more reliable and scalable method for synthesizing fluorescent defects on SWCNTs is needed for translating from fundamental studies to practical applications. Here, we introduce a fast and reproducible method for creating oxygen-doped fluorescent defects on SWCNTs. The maximum intensity of the defect emission is reached within 40 secs, which is at least 24 times faster than reported values. The oxygen source is provided by the photo-dissociation of the hypochlorite ions and the doping occurs by direct attachment of the oxygen atom onto the SWCNT wall. This method produces minimum non-fluorescent defects, and more than 95% of the resulting SWCNTs contain fluorescent defects. We also built a high-throughput flow reactor to synthesize the O-doped SWCNTs at scale and used them for imaging vascular and lymphatic systems.
(Invited) Perylene-Based Functionalization of Carbon Nanotubes
Authors: Setaro Antonio
Published: February 2020

Functionalization aims at granting compounds with additional features. This is achieved by typically attaching novel groups to the original systems. The aftermath of such process yields complexes whose charcteristics often result in more than just the mere sum of the initial products. The specific character of the functionalized structure, moreover, depends upon the way the functionalization strategy has been pursued.

We will focus on the carbon nanotubes functionalization through perylene, an aromatic molecule emitting in the excitation window of most single-walled nanotubes commercially available. We have previously shown that the perylene core of custom surfactants was able to attach though pi-pi stacking interactions onto the sidewall of CNTs while ensuring efficient excitation transfer to the tubes [1,2]. Here we will show how starting from the same elements (perylene and nanotubes) and pursuing different functionalization routines, we achieve systems with different features and functions. In particular, we will compare the characteristics of perylene-comprising polymers wrapped around the tubes [3] with the peculiarities of perylene covalently attached to the nanotubes following a novel conjugation-preserving routine we recently developed [4]. We will highlight the difference among the properties of the final products as well as the applications they would be suitable for.

[1] F Ernst et al., Adv. Funct. Mat. 2012, 22, 3921.

[2] F Ernst et al., Appl. Phys. Lett. 2013, 102, 233105.

[3] K. Huth et al, Small 2018, 14, 1800796.

[4] A Setaro et al. Nat. Comm. 2017, 8, 14281.
(Invited) Superacid-Surfactant Exchange
Authors: Wang Peng , Kim Mijin , Wang YuHuang
Published: February 2020

Attaining aqueous solutions of individual single-walled carbon nanotubes is the critical first step for harnessing the extraordinary properties of these materials. However, current approaches cause structural damage and cuts the nanotubes into short pieces. In this talk, we will introduce an unexpectedly simple solution to this decade-old challenge by directly neutralizing a nanotube-superacid solution in the presence of a surfactant. This straightforward superacid-surfactant exchange (S2E) involves two simple solution-mixing steps that completely eliminate the need for both ultrasonication and ultracentrifugation. The result allows us to advance multiple fronts, including aqueous sorting of ultralong nanotubes and stretchable thin film transistors with high carrier mobility.
(Invited) Carbon Nanotube Photoluminescence Solvatochromism in Biomedicine: Spectroscopy, Imaging, and Modulation
Authors: Heller Daniel A. , Baker Hanan , Budhathoki-Uprety Januka , Cupo Christian , Harvey Jackson , Jena Prakrit Vaibhav , Langenbacher Rachel E , Mittal Jeetain , Roxbury Daniel , Shah Janki , Williams Ryan M. , Zerze Gul , Zheng Ming
Published: February 2020

Modulation of the carbon nanotube photoluminescence band position has implications for applications such as sensing and imaging. Carbon nanotube photoluminescence solvatochromism, the hypsochromic or bathochromic shifting of nanotube emission, can be induced via changes in the local dielectric environment. We developed methods to modulate nanotube solvatochromic behavior to improve sensor responses, and we developed tools to observe solvatochromism within live cells and, recently, live animals.

We found that nanotube solvatochromism extends to variations of local electrostatic charge, induced by adsorption/desorption of polyelectrolytes on the nanotube surface, such as proteins and nucleic acids. We also found that dielectric and charge-mediated solvatochromism can be compounded to exacerbate the response. Upon triggered desorption of a polyelectrolyte, such as upon desorption of RNA upon hybridization, for instance, amphiphilic molecules can adsorb to the recently-uncovered nanotube surface. The adsorption displaces water to result in hypsochromic shifting, which can be additive, as polyelectrolyte desorption will also cause a hypsochromic shift. We found that the amphiphile may be a surfactant but, recently, we found that proteins can result in a similar response, facilitating the detection of viruses.

We developed tools to image changes in nanotube emission in live cells (near-infrared hyperspectral microscopy) and, recently, live animals (preclinical, near-infrared hyperspectral imaging). Carbon nanotube solvatochromism-based sensors, in combination with spectral imaging tools, allow measurements of biomarkers, drugs, and metabolites in live cells and organisms, facilitating improvements in disease detection, drug development, and biomedical research.
(Invited) Organic/Inorganic Hybrid Interfaces with Swcnts for Energy Harvesting and Conversion
Authors: Blackburn Jeffrey L. , Sulas Dana , Kang Hyun Suk , Habisreutinger Severin N. , Johnson Justin C. , Ferguson Andrew John , Miller Elisa M.
Published: February 2020

Low-dimensional semiconductors provide a rich tapestry of tunable optical and electrical properties for a wide variety of applications. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have shown tremendous potential in applications ranging from digital logic, biological imaging, quantum information processing, photovoltaics, and thermoelectric energy harvesting. Energy harvesting applications rely critically upon the creation of tailored interfaces that enable the movement of energetic species (excitons, electrons, holes) in specified directions. While organic energy harvesting devices often employ interfaces between distinct organic species such as polymers, fullerenes, and carbon nanotubes, hybrid interfaces between organic and inorganic semiconductors have unique properties that are relatively unexplored. In this talk, I will discuss our recent efforts at constructing novel hybrid interfaces between s-SWCNTs and low-dimensional inorganic semiconductors. I will highlight time-resolved spectroscopy results that illustrate exceptionally long-lived photoinduced charge separation across such interfaces. These studies provide insight into some of the remarkable properties of these interfaces that can enable efficient solar energy harvesting and conversion to fuels.
Spinning-Disc Confocal Microscopy in the Second Near-Infrared Window (NIR-II)
Authors: Zubkovs Vitalijs , Antonucci Alessandra , Schuergers Nils , Lambert Benjamin Paul , Latini Andrea , Ceccarelli Raino , Santinelli Andrea , Rogov Andrii , Ciepielewski Daniel , Boghossian Ardemis Anoush
Published: February 2020

Fluorescence microscopy in the second near-infrared optical window (NIR-II, 1000-1350 nm) has become a technique of choice for non-invasive in vivo imaging. The deep penetration of NIR light in living tissue, as well as minimal or complete absence of tissue autofluorescence within this range, offers increased resolution and contrast with even greater penetration depths. Here, we present a custom-built spinning-disc confocal laser microscope (SDCLM) that is specific to imaging in the NIR-II. The SDCLM achieves a lateral resolution of 0.5±0.1 µm and an axial resolution of 0.6±0.1 µm, showing a ~17% and ~45% enhancement in lateral and axial resolutions, respectively, compared to the corresponding wide-field configuration. We furthermore showcase several applications that demonstrate the use of the SDCLM for in situ, spatiotemporal tracking of NIR particles and bioanalytes within both synthetic and biological systems.
Fluorescent Ultrashort Nanotubes from Defect-Induced Chemical Cutting
Authors: Li Yunfeng , Wu Xiaojian , Kim Mijin , Qu Haoran , Fortner Jacob , Wang YuHuang
Published: February 2020

Ultrashort single-walled carbon nanotubes that fluoresce brightly in the shortwave infrared are potential candidates in bio-imaging and bio-sensing. However, the great potential has been largely underexplored for decades due to inherent challenges in synthesizing this material. In this work, we have successfully addressed this synthetic challenge by implanting chemical defects along the lengths of nanotubes and subsequently cutting the structure using H2O2. This simple two-step process leads to the synthesis of fluorescent ultrashort nanotubes with a narrow length distribution and a yield as high as 53%. This work sheds new insights on the role of defects in carbon nanochemistry and makes fluorescent ultrashort nanotubes highly accessible, which may enable many basic and applied studies of nanotubes in bioimaging, sensing, photophysics, carbon nanochemistry, and quantum technologies.
Carbon Nanotube Compositie Based Sensor for Detecting Hydrogen Molecules
Authors: Lee Junyeop , Kim jae Keon , Kim Samhwan , Jung Daewoong
Published: February 2020

Accuracy and precise measurement of gas values is crucial for recognizing many critical biological and physical signs, as gas values present significant signals for monitoring chemistry, biology, environments and medical industries. Many sensing materials such as metal compounds, composite, nanowires, and polymers, for detecting gas have been investigated, and the merits and demerits of each have been reported [1,2]. Recently, carbon-based nanomaterials, including zero-dimensional fullerenes, one-dimensional carbon nanotubes (CNT), and two-dimensional graphene, have shown probable in gas sensor applications. Many prior works have reported their superior properties, including higher electrical conductivity, mechanical durability and chemical stability, and a larger surface area.In particularly, CNTs are well known material for sensor applications due to their stable graphite configuration, structural endurance under chemical/physical treatment processes, and mechanical characteristics. Moreover, lots of efforts to realize CNTs as chemical sensor material were performed by many groups previously [3]. They reported that the concentrations of electrons and holes in CNTs play important role in sensitivity of the CNT-based gas sensor. However, although many techniques were introduced to fabricate the CNT-based gas sensors, such device manufacturing processes were intricate and have limited repeatability and reliability, which makes hard them to be commercialized.The CNT yarn was introduced, reported and characterized previously by group using simple dry spinning method [4]. The CNT yarn has good electrical property with a high conductivity, and flexible structural property, and chemical stability. In this work, we develop the ability of CNT yarn for detecting hydrogen and carbon monoxide concentrations. Furthermore, we demonstrate that metal nanoparticles on the surface of CNT yarn highly affect the sensitivity of the CNT yarn-based gas sensor. Therefore, this study focused on the analysis and characteristics of the gas sensor using binary composite as gas sensor.

References

[1] Liu et al., Sensors 12, 9635 (2012).

[2] Varghese et al., Sens. Actuators. B 218, 160 (2015).

[3] Llobet et al., Sens. Actuators. B 179, 32 (2013).

[4] Hwang et al., Puller. Nanotub. Car. N. 24, 305 (2016).
(Invited) Super-Localization of Excitons in Carbon Nanotubes at Cryogenic Temperatures
Authors: Raynaud Christophe , Claude Théo , Amara Raouf , Graf Arko , Zaumseil Jana , Lauret Jean-Sébastien , Chassagneux Yannick , Voisin Christophe
Published: February 2020

At cryogenic temperature and at the single emitter level, the optical properties of single-wall carbon nanotubes depart drastically from that of a one-dimensional (1D) object. In fact, the (most usually unintentional) localization of the exciton in local potential wells leads to nearly 0D behaviors such as photon antibunching, spectral diffusion, inhomogeneous broadening... Here, we present an hyperspectral imaging of this exciton self-localization effect at the single nanotube level using a super-resolved optical microscopy approach. We report on the statistical distribution of trap depths, size and density. Together with a excitation resolved photoluminescence approach, we show that the excitonic states are deeply modified by the interface disorder inducing a remarkable discretization of the S11 absorption spectrum.
Nanocarbons through the Artist’s Lens
Authors: Cohen Joseph , Harvey Jackson , Chyan Yieu , Tour James M. , Heller Daniel A.
Published: February 2020

Carbon nanomaterials have unique structural and optical properties that have been under-explored for the development of artistic applications. We developed pigments and fluorescent dyes using single-walled carbon nanotube and graphene to create visual art. We developed carbon nanotube-based pigments for application to paper and other solid substrates with optimal fluorescence in the infrared. The photoluminescence of these paints was used to generate artwork that illuminates the unique properties and opportunities inherent in the material. We developed several methods to visualize the near-infrared nanotube emission, including novel lighting solutions as well as imaging solutions, for use with large-scale visual art formats.

We also developed large-scale visual art using graphene as a pigment. Laser-induced graphene was synthesized in-situ on paper substrates with dimensions up to 20 x 30 inches. Machine-automated processes allowed the faithful reproduction of computer-generated artwork into graphene on an “artist’s canvas.”
Carbon Nanotube-Inorganic Hybrid Systems and Devices
Authors: Palma Matteo
Published: February 2020

We present different strategies for the generation of multifunctional nanomaterials employing single-walled carbon nanotubes (SWCNTs). In particular, we will discuss the formation of nanohybrids via the in-solution assembly of inorganic nanomaterials to SWCNTs, employed as nanoelectrodes or as nanoscale vector templates. Notably, both static and dynamic heterostructures were assembled, as well as nanoscale electronic devices; this allowed us to study and tailor various systems for different applications.

We will first discuss the in-solution assembly of organic-inorganic heterostructures consisting of single Quantum Dots (QDs) univocally linked at the terminal ends of individual SWCNTs. Monofunctionalized SWCNT-QD heterostructures were obtained and photophysical investigations at the single nanohybrid level showed evidence of electronic coupling [1]. Additionally, DNA linkers of differing lengths were used as molecular rulers to control the distance, and hence tune the energy/charge transfer between the two nanostructures in these SWCNT-QD nanohybrids.[2] A dynamic SWCNT-QD hybrid was also designed and assembled using a G-quadruplex DNA aptamer linker, so that the distance between the SWCNT and QD could be dynamically modulated by the introduction and removal of potassium ions (K+);[2] the system was further found to be sensitive to K+ concentrations between 1pM and 25mM. By and large, this approach opens the possibility of assembling tailored optoelectronic and light harvesting systems with single-particle control.

Finally, we will present the direct synthesis of multiplexed metal nanowire based devices using carbon nanotubes as vector templates. SWCNTs were filled with specifically designed metal precursors and dispersed in aqueous solution, enabling solution processability. The filled SWNTs were immobilized from solution onto different pre-patterned electrodes via a low-cost dielectrophoresis methodology. Metal nanowires were then grown by a facile and low temperature annealing treatment, while the nanotubes were removed using an oxygen plasma once immobilized in a device configuration. Electrical characterizations demonstrated the successful fabrication of metal nanowire electronic devices (no gate dependence).[3] Overall the strategy presented allows for a facile, low-cost and direct synthesis of multiple metal nanowire based devices for nanoelectronic applications.

[1] Small, 2017,13, 1603042

[2] Advanced Science, 2018, 5, 1800596

[3] Submitted
Effect of Seed Layer on Grain Size of Electroplated Cu
Authors: Lin Yen-Chen , Chan Po-Fan , Dow Wei-Ping
Published: February 2020

Copper is widely used as the wires of semiconductor. The grain size of copper has been approved to influence its strength, ductility and conductivity. The larger the grain size, the less the grain boundary. Accordingly, the copper conductivity increases because grain boundary is the resistance of electronic transfer. Hence, the larger the grain size is, the better the copper conductivity will be. In this work, we attempt to produce thick copper film with large grain size by means of electroplating.

We found that seed layers could influence the structure of electroplated copper. Hence, we employed various seed layer materials, such as titanium, copper. The cross-section of the electroplated copper was observed by optical microscope (OM), focused ion beam (FIB), scanning electron spectroscopy (SEM) and transmission electron microscope (TEM). The plating additives were characterized using potentiostatic.
(Invited) A Tutorial on Atomic Layer Deposition and Its Application in Lithium-Ion Batteries
Authors: Detavernier Christophe
Published: February 2020

Atomic layer deposition (ALD) is a deposition technique where thin films are deposited from sequential gas-surface reactions. Thanks to the self-limiting nature of these reactions, ALD provides interesting deposition characteristics such as atomic scale thickness control and deposition onto complex shaped substrates (including powders) with excellent uniformity and conformality. These features have enabled ALD to become a well-established tool in semiconductor manufacturing, and there is a growing consensus that other domains such as catalysis and energy storage can also strongly benefit from these unique coating characteristics.

In this tutorial, two different types of potential applications of ALD in the field of lithium-ion batteries will be discussed:

- ALD of the active components of a lithium-ion battery (positive and negative electrodes, solid electrolytes), either as functional layers in thin film batteries, or as thin film model systems. Novel battery concepts such as the 3D thin-film lithium-ion microbattery are promising for applications such as on-chip energy storage, and ALD could play an important role in the deposition of critical components of these battery stacks onto 3D nanostructured substrates, in particular for the interfaces and solid-electrolyte layers. Moreover, the excellent film quality, control over composition and crystallinity provided by ALD enable the synthesis of thin, planar model systems. Such thin film model systems with well-controlled properties provide simplified one-dimensional currents and are unbothered by the complex interplay of various components of the classical battery, such as binder, conductive additive, particle size, solvent composition etc, and can thus reveal potentially beneficial battery chemistries which would otherwise be obscured, or provide insights into otherwise very complex systems.

- ALD modification of surfaces and interfaces. In particular, ALD of protective coatings onto electrode materials has been explored extensively to stabilise interfaces and thus enhance cell cycle life. As battery ageing for traditional lithium-ion batteries can already be problematic, novel architectures, battery concepts and material chemistries pose increasingly greater challenges in this direction, and surface/interface engineering have become important strategies to overcome ageing and improve battery performance. To obtain a high quality coating on the complex surface of battery electrodes, the low processing temperature in combination with the thickness control, uniformity and conformality provided by ALD can become key advantages.
(Invited) ALD and MLD of Functional Thin-Film Coatings for Enhanced Performance in Li-Ion and Li-Metal Solid-State Batteries
Authors: Vereecken Philippe M. , Gandrud Knut Bjarne , Put Brecht , Hollevoet Simon , Labyedh Nouha , Debucquoy Maarten , Mees Maarten , De Taeye Louis , Swamy Reddy Keerthi Dorai , Pitillas Martinez Andrea , Detavernier Christophe
Published: February 2020

The key figures of merit for batteries are Energy density, charging time (C-rate) and cycling Life time. In this invited talk we will focus on the application of continuous closed thin films as artificial interfaces in large capacity batteries or for the fabrication of functional battery components in micro-batteries. We will deal mostly with the perspective of device performance where the ALD and MLD processes merely provide the films and enable their ultrathin, continuous and conformal nature. Nanoscale film thickness allows for low interface and cell resistance even when the materials themselves are poor conductors. For example. LiPON (N-doped Li3PO4) is a solid electrolyte interesting because it is stable against metallic lithium but, because of its poor ionic conductivity (<10-6 S/cm) only practically useful for thicknesses under few hundred nanometers. Even further, materials which are not solid electrolytes by their own merit (e.g. TiO2) still have ion-transparent properties up to several tens of nanometer and can be used as ion transparent artificial interfaces in contrast to alumina which is an insulator for Li-ions. For coating of individual particles, ideally coatings which have both electronic and ionic conducting (or transparent) properties. Doping is one approach to enhance either conductivity.

When scaling down of the film thickness also finite size effects have to be considered, for example, the thickness of the electrical double layer, diffusion layer thickness and the electric field over the dielectric.

ALD and MLD can be used also to fabricate functional nanomaterials; i.e. by harvesting nanoscale effects. For example, nanocomposite solid electrolyte films of a few tens of nanometers were fabricated by a combination of MLD of inorganic-organic hybrid alucone thin-films, etching the organic fraction in water and functionalization by ALD of Li2CO3 and Li3PO4. For the first time, enhanced ion conductivity is shown by harvesting the enhanced ion conductivity at oxide/ion conductor interfaces.

Finally, volume changes during charge and discharge are limiting the cycle life-time of batteries, especially for rigid solid-state batteries. Also ALD thin-films suffer from the mechanical strain and the benefits of the “closed” protective film are lost. Therefore, MLD of hybrid organic/inorganic coatings is explored to enable more elastic coatings for improved cycle life time.
(Invited) Vapor-Deposited MOFs As Gap-Filling Low-k Dielectrics
Authors: Ameloot Rob
Published: February 2020

Metal-organic frameworks (MOFs) are an intriguing class of porous crystalline materials with record internal surface areas. There is tremendous potential for integrating MOFs into microelectronics, e.g. as active sensor coatings or low-k dielectrics.[1] A key enabling step in leveraging the properties of MOFs in microelectronics will be the development of robust thin film deposition methods. Most procedures for the deposition of MOF thin films are incompatible with microelectronic fabrication because of corrosion and contamination issues.

We recently demonstrated chemical vapor deposition (CVD) of MOF thin films.[2] The MOF-CVD process allows conformal growth of thin films and extends MOF processing to one of the most commonly used techniques in thin film research and manufacturing. Future directions and potential applications of MOF-CVD coatings will be discussed, with special attention to their integration as gap-filling low-k materials in on-chip interconnects.

References

[1] Stassen, I.; Burtch, N.; Talin, A. A.; Falcaro, P.; Allendorf, M. D.; Ameloot, R. Chem. Soc. Rev.
2017, 46, 3185–3241.

[2] Stassen, I.; Styles, M.; Grenci, G.; Van Gorp, H.; Vanderlinden, W.; De Feyter, S.; Falcaro, P.; De Vos, D. E.; Vereecken, P.; Ameloot, R. Nat. Mater.
2016, 15 (3), 304–310.

Figure 1
Application of Atomic Layer Deposition for Fabrication of Solar Cells
Authors: Frohlich Karol , Mikolášek Miroslav , Subair Riyas , Nadazdy Vojtech , Rosová Alica , Precner Marian , Tasaltin Nevin , Alturk Elif , Tekin Emine , Aslan Emre , Ates Turkmen Tulin , Majková Eva
Published: February 2020

Atomic layer deposition (ALD) is exceptional deposition technique because it allows for growth of high quality films on large are substrates at low deposition temperatures. In our contribution ALD was employed for preparation of transparent conducting electrodes and for encapsulation of fabricated solar cells.

Al-doped ZnO films were used for transparent conducting electrodes. Deposition was carried out at temperatures between 150 and 250 °C on Si and quartz substrates. Diethyl zinc and trimethyl aluminum were used as precursors and water vapors as reactant. Al-doping was performed by inserting Al2O3 cycles in ZnO growth. Deposition of 1 Al2O3 layer per 7 deposited ZnO layers gave the best results. Resistivity of the Al-doped ZnO films depended on the deposition temperature and film thickness. Transition electron microscopy revealed typical columnar growth of the films with fine grained polycrystalline region close to the substrate. The films with the thickness above 100 nm prepared at 250 °C showed resistivity of 1 mΩcm. This corresponds to the sheet resistance of 40 Ω/square. Hall measurement revealed electron concentration of 4*1020 cm-3 and mobility of 15 cm2Vs-1 for the films with resistivity of 1 mΩcm. Work function of 4.4 eV was measured by Kelvin probe. Optical transmittance of the films was higher than 80% in the wavelength range between 400 and 900 nm.

Al-doped ZnO transparent electrodes were used for fabrication of perovskite-type conventional planar solar cell. CH3NH3 PbI3 perovskite was used as absorbing layer, Spiro-OMeTAD as hole transport layer and Au/Ag as top contact layer. Properties of the solar cell with Al-doped ZnO electrode are compared with inverted planar solar cell using indium tin oxide as a transparent electrode.

Inorganic-organic hybrid perovskite solar cells suffer from poor stability in ambient atmosphere. Oxygen and moisture are believed to be reason for the solar cell degradation. To protect the cells against ambient atmosphere influence ALD prepared Al2O3 films were employed for encapsulation. Trimethyl aluminum was used as precursor while either water vapors or ozone were applied as reactants. Deposition of the Al2O3 films took place at 50°C.

Power conversion efficiency of the solar cell encapsulated by 24 nm Al2O3 thin film deposited using water vapors as reactant decreased to 60% while unprotected solar cell degraded down to 10% of its initial value after 20 days in ambient atmosphere. In our contribution we compare properties of perovskite solar cell encapsulated by ALD Al2O3 films prepared using water vapors or ozone as reactants.
Molybdenum Disulfides and Diselenides By Atomic Layer Deposition
Authors: Zazpe Raul , Prikryl Jan , Charvot Jaroslav , Dvorak Filip , Krbal Milos , Bures Filip , Macak Jan M.
Published: February 2020

The success of graphene opened a door for a new class of chalcogenide materials with unique properties that can be applied in the semiconductor technology [1]. Monolayers of two-dimensional transition metal dichalcogenides (2D TMDCs) possess a direct band gap [2] that is crucial for optoelectronic applications. Additionally, the direct band gap can be easily tuned by either chemical composition or external stimuli. Next to the optoelectronic applications, where a monolayer planar structure is necessary to employ, a layer of standing flakes, which possesses a large surface area, can be used for hydrogen evolution [3] a photodegradation of organic dyes [4] or as electrodes in Li ion batteries [5].

In principle, TMDCs can be prepared by various top-down (e.g. exfoliation) and bottom-up techniques, such as chemical vapor deposition (CVD) and atomic layer deposition (ALD) growth techniques [1]. MoS2, a typical representative of TMDCs, has been widely studied for many applications. Recently, the possibility to employ ALD as a technique to grow MoS2 has been reported. In these works (CH3)2S2 [6] or H2S [7, 8] were used as the S precursor and Mo(CO)6 [6], MoCl5 [7] or Mo(thd)3 [8] as the Mo precursors. From the practical point of view, MoSe2 is even more interesting than MoS2 since MoSe2 possesses a higher electrical conductivity than MoS2 [9, 10]. Recently, we have shown that ALD deposition of MoSe2 [11] or Mo-O-Se [12] using ((CH3)3Si)2Se as the Se precursor and the MoCl5 or Mo(CO)6, respectively, as the Mo precursors is feasible.

The presentation will focus on the synthesis of MoS2 and MoSe2 by ALD, their characterization and applications in various fields. Experimental details and some recent photocatalytic and hydrogen evolution results will be presented and discussed.

References:

[1] A. V. Kolobov, J. Tominaga, Two-Dimensional Transition-Metal, Dichalcogenides. Springer Series in Materials Science, Springer International Publishing AG, Switzerland 2016

[2] B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti, A. Kis, Nat. Nanotechnol. 2011, 6, 147.

[3] L. Wang, Z. Sofer, J. Luxa, M. Pumera, Adv. Mater. Interfaces
2015, 2, 1500041

[4] Y. Wu, M. Xu, X. Chen, S. Yang, H. Wu, J. Pan, X. Xiong, Nanoscale
2016, 8, 440

[5] D. Ilic, K. Wiesener, W. Schneider, H. Oppermann, G. Krabbes, J.Power Sources
1985, 14, 223

[6] Z. Jin, S.Shin,D.H.Kwon, S. J.Han,Y. S.Min,Nanoscale
2014, 6, 14453.

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(Invited) Organic Thermoelectric Materials and Devices
Authors: Yee Shannon K.
Published: February 2020

Within the last 3 years, thermoelectric technologies have seen renewed global deployment providing unique solutions to pressing thermal problems. Today thermoelectric technologies are helping to ensure vaccines viably reach the most remote locations in the world, are providing personal comfort in wearable devices addressing medical circulatory conditions, and are being designed for integration into electric vehicles thereby reducing the global warming contributions of refrigerants in conventional air conditioning systems. The majority of these technologies have resulted from innovative engineers utilizing conventional materials in niche applications, however, additional societal contributions can be achieved by leveraging the large-area processability and abundance of polymer-based thermoelectrics.

Unfortunately, the material performance of polymer-based thermoelectric materials is lacking compared to their inorganic counterparts. To circumvent this challenge, composites or hybrid organic-inorganic materials are often employed in functional devices. Furthermore, while there is an abundance of p-type materials to select from, there are few air-stable n-type thermoelectric materials. Metal coordinated polymers (or metallo-organic polymers) are one promising class of thermoelectric materials where a metal (or semimetal) atom is present along the polymer backbone. This structure produces periodic centers of high electron density, which, when coupled to the vibrational modes (e.g., vibrons or phonons), could result in appreciable power factors. Both air-stable p-type and n-type metal coordinated polymers can be readily synthesized from abundant materials and are promising scalable alternatives to inorganics that leverage solution processing.

This talk will first provide a motivating overview of emerging thermoelectric technologies being developed. Next, this talk will discuss progress in synthesizing and controlling the thermoelectric properties of poly(nickel-ethenetetrathiolate) (i.e., Ni-ETT) and poly(nickel-tetrathiooxalate) (i.e., Ni-TTO), which are both air-stable n-type thermoelectric materials containing nickel along the polymer backbone. Next, this talk will discuss our work studying poly(3-alkyl-chalcogenophene), where the isovalent series of thiophene, selenophene, and tellurophene were investigated. Finally, this talk will introduce new thermoelectric device architectures, specifically printable and knittable devices, that are enabled by these materials. Throughout this talk emphasis will be placed on the engineering and scaling challenges, which have been overlooked in the pursuit of high performance materials, but are most critical to realizing thermoelectric devices.
(Invited) Electrochemical Synthesis of Chalcogen and Metal Chalcogenide Nanostructures for Thermoelectric Applications
Authors: To Dung , Seyedmahmoudbaraghani Saba , Yu Sooyoun , Myung Nosang Vincent
Published: February 2020

In an attempt to overcome some of the drawbacks to the combustion of fossil fuel – such as a large carbon footprint and non-renewability – thermoelectric generators (TGs) have gained a considerable attention as a sustainable alternative technology, since they are environmentally friendly and have the ability of recycling abundant waste heat. Nanostructuring of thermoelectric materials can improve the dimensionless thermoelectric figure of merit (ZT) due to their abilities to independently control phonon scattering and energy-dependent scattering of electrical carriers. In comparison to different semiconductors for thermoelectric materials (e.g. IV and III-IV groups), chalcogens and metal chalcogenides show a lower lattice thermal energy due to their relatively large atomic masses and complex crystal structures, resulting in higher values of ZT.

Among various methods employed to synthesize chalcogen and metal chalcogenide nanostructures, electrochemical methods exhibit many advantages, such as the ability to control composition, grain size, and crystallinity including defects, and near room temperature deposition conditions. In this work, we will discuss the electrochemical synthesis of chalcogens and metal chalcogenides and correlate the structure with thermoelectric properties.
(Invited) Role of Anharmonicity on Thermoelectric Properties of Fully Dense Single-Crystalline Snse
Authors: Bhattacharya Sriparna , Chen Yang-Yuan , Rao Apparao M.
Published: February 2020

Thermoelectric (TE) materials enable conversion of “waste” heat to electricity, leading to environmentally friendly solutions for power generation applications. The thermal-to-electrical energy conversion efficiency of a TE material is largely determined by its dimensionless figure-of-merit, ZT = S2σT/κ that consists of interrelated material properties, viz., the Seebeck coefficient (S), electrical conductivity (σ), and the thermal conductivity (κ). Recently, single-crystalline SnSe has attracted much attention due of its record high figure-of-merit ZT ≈ 2.6, [1] that was debated in subsequent reports due to the low mass density of these single crystals. [2] We performed structural, electrical, and thermal transport measurements on high-quality fully dense SnSe single crystals over a wide temperature range along the major crystallographic directions, that yielded a maximum ZT ~ 1 along one of the major crystallographic directions.[3] It is well known that phonon anharmonicity is one of the contributing factors that yields a remarkably low κ in binary SnSe. As an attempt to understand the role of phonon anharmonicity, we performed a combined temperature-dependent polarized Raman spectroscopic and heat-capacity study on fully dense single-crystalline SnSe, which revealed that the anharmonicity in SnSe is driven by soft optical modes in its bc plane. [4] This study provides a deeper understanding of the role of phonon-phonon scattering and anharmonicity leading to reported thermal transport properties of SnSe.

[1] Zhao, L.-D., Lo, S.-H., Zhang, Y., Sun, H., Tan, G., Uher, C., Wolverton, C., Dravid, V. P., Kanatzidis, M. G. Ultralow Thermal Conductivity and High Thermoelectric Figure of Merit in SnSe Crystals, Nature 2014, 508 (7496), 373–377.

[2] Wei, P. C., Bhattacharya, S., He, J., Neeleshwar, S., Podila, R., Chen, Y. Y., Rao, A. M., The Intrinsic Thermal Conductivity of SnSe, Nature 2016, E1–E2.

[3] Wei, P.C., Bhattacharya S., Liu Y-F., Liu F., He J., Tung Y-H., Yang C-C., Hsing C-R., Nguyen D.L., Wei C-M., Chou M-Y., Lai Y-C., Hung T-L, Guan S-Y., Chang C-S., Wu H-J., Lee C-H., Li W-H., Hermann R. P., Chen Y-Y., Rao A.M., Thermoelectric figure-of-merit of fully dense single crystalline SnSe, ACS Omega, 2019, 4 (3), 5442–5450.

[4] Liu F., Parajuli P., Rao R., Wei P.-C., Karunarathne A., Bhattacharya S., Podila R., He J., Maruyama B., Priyadarshan G., Gladden J. R., Chen Y.-Y., Rao A.M., Phonon Anharmonicity in single-crystalline SnSe, Phys. Rev. B 2018, 98, 224309.
(Invited) Thermoelectric Energy Conversion and Thermal Memristance and Switching
Authors: Urban Jeffrey J
Published: February 2020

Heat and charge are fundamental energy carrying modes relevant to nearly all dynamic properties of interest in engineering, physics, and modern energy technologies. Here, I will discuss the design and understanding of transport properties in complex nanoscale systems where the dimensional constraints are changed systematically to reveal fundamental principles of heat and charge transport. The first part of this talk will focus on heat and charge transport in polymeric and hybrid nanomaterials, revealing the physical origins of scaling laws for charge transport in these materials. The second portion of my talk will discuss heat and charge transport in a different class of hybrid materials, the ever-popular perovskites. Here, I will briefly discuss possible origins for the ultra-low thermal conductivity observed in nanoscale samples, and new measurement approaches for resistive bulk perovskites. The final portion of my talk will briefly highlight strong deviations from the Wiedemann-Franz law in materials with electronic phase transitions, and possible applications of this phenomenology for novel devices exhibiting, for example, thermal rectification and thermal memristance.

Selected references:

1. Organic electronics: one model to rule them all, Nature Materials (2017)

2. Polymer morphology dominates over energy-dependent scattering in inorganic-organic hybrid thermoelectrics, Nature Communications (2018)

3. Ultralow thermal conductivity in all inorganic halide perovskites, PNAS (2017)

4. Phonon dispersion lifetimes of organic-inorganic hybrid perovskite CH3NH3PbI3 from Inelastic X-ray scattering (2018, in review).

5. Anomalously low electronic thermal conductivity in metallic vanadium dioxide, Science (2017)

6. Solid-state thermal rectification and negative differential thermal resistance using junctions of phase transition materials, Phys. Rev. Applied (2018)
(Invited) Mie-like Scattering of Phonons by a Single Vacancy in IV-VI Compounds
Authors: Guo Ruiqiang , Lee Sangyeop
Published: February 2020

Defects engineering has been a widely used approach for developing low thermal conductivity materials. Also, for some materials (e.g., IV-VI compound), considerably large amount of vacancies was often observed in single crystalline samples. The atomic vacancy in dilute case was assumed as a point defect that can cause the Rayleigh scattering with its rate proportional to the fourth power of phonon frequency. Due to the large dependence of scattering rate on phonon frequency, a vacancy was considered to only weakly suppress the mode thermal conductivity of low frequency acoustic phonons. We show that this does not hold for IV-VI materials. We compare the phonon scattering by a single vacancy in group IV (diamond and Si) and IV-VI (PbTe and GeTe) crystals using an exact ab initio Green’s function approach. The phonon-vacancy scattering rates in diamond and Si follow the well-known fourth-power dependence on phonon frequency. However, PbTe and GeTe exhibit phonon scattering rates that have much weaker frequency dependence. As a result, a vacancy scatters low frequency acoustic phonons more strongly in PbTe and GeTe than in Si and diamond. This unusual behavior in PbTe and GeTe originates from the significant changes of interatomic force constants that extend up to the distance of 10 angstrom from the vacancy site. Therefore, a vacancy in IV-VI materials cannot be assumed as a point defect but its finite size should be considered for phonon scattering. In contrast, a vacancy in Si and diamond changes interatomic force constants only up to 3 angstrom range. Our study provides new insights on the phonon spectral contribution to thermal transport when vacancies exist in IV-VI materials and will help to develop low thermal conductivity materials by engineering vacancies.