bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid-Film Rupture for Web-like Ag Nanowires Toward High-Performance Organic Schottky Barrier Transistors
Authors: Sim Hye Ryun , Lee Sangjun , Lee Juhyeok , Hassan Syed Zahid , Nam Geon-Hee , So Chan , Sim Kyu Min , Chung Dae Sung
Published: December 2024

Organic vertical transistors are promising device with advantages such as high operation speed, high saturation current density, and low-voltage operation due to their short channel length. However, a short channel length causes undesirably high off-current, which affects the on–off ratio and power consumption. This study presents a breakthrough in the development of high-performance organic Schottky barrier transistors (OSBTs) with a low off-current by utilizing a near-ideal source electrode with a web-like Ag nanowire (AgNW) morphology. This is achieved by employing a humidity- and surface-tension-mediated liquid-film rupture technique, which facilitates the formation of well-connected AgNW networks with large pores between them. Therefore, the gate electric field is effectively transmitted to the semiconductor layer. Also, the minimized surface area of the AgNWs causes complete suppression of the off-current and induces ideal saturation of the OSBT output characteristics. p- and n-type OSBTs exhibit off-currents in the picoampere range with on/off ratios exceeding 106 and 105, respectively. Furthermore, complementary inverters are prepared using an aryl azide cross-linker for patterning, with a gain of >16. This study represents a significant milestone in the development of high-performance organic vertical transistors and verifies their applicability in organic electronic circuitry.
(Invited) Advancement in Neuromorphic Devices for Detection of Complex Stimuli with Low Power Consumption Utilizing Cross-Linked Electrolyte
Authors: Kim Su-Kyung , Seong Tae-Yeon
Published: December 2024

In the quest to create computing systems that mimic the brain’s remarkable ability to process data efficiently and in parallel, researchers have recognized the need for in-memory computing devices that can overcome the limitations of the traditional von Neumann architecture. Recently, neuromorphic devices like memristors and synaptic transistors have been developed to emulate the process of neurons. However, memristors face challenges in simultaneously handling signal transmission and learning tasks. As an alternative, synaptic transistors have gained attention owing to their adjustable weight and improved non-volatile synaptic functionality. Notably, synaptic transistors with electrolyte insulating layers can form electric double layers (EDLs) with high capacitance per unit area, because of mobile ions and dipoles. This enables efficient gate-controlled synaptic behavior. Additionally, amorphous oxynitride semiconductors, used as n-type channels, exhibit superior mobility compared to other materials like 2D transition metals, perovskites, organic materials, and oxides. In our investigation, therefore, we employed a cross-linked poly-4-vinyl phenol (PVP) gate insulator to enhance the synaptic properties of oxynitride thin film transistors.

In our study, we employed zinc oxynitride (ZnON) as the channel material. ZnON offers greater stability compared to oxide materials due to its reduced oxygen vacancy concentration. We precisely controlled the solution composition and the curing process during the deposition of the electrolyte insulating layer. To optimize the formation of electric double layers (EDLs), we varied the weight ratio of poly(melamine-co-formaldehyde) methylated (PMF) and poly-4-vinyl phenol (PVP). Our investigation focused on synaptic properties, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), long-term memory, and high-band filtering. All samples exhibited a counter-clockwise hysteresis curve and a memory window exceeding 2 V at 1 V of drain voltage (Vd), except for the PVP:PMF 2:1 sample. Notably, the device with a 10:1 weight ratio demonstrated the most effective EPSC response, showing a gradual increase in EPSC with repeated gate voltage (Vg) pulses. Additionally, we analyzed the EPSC characteristics under various Vg pulse conditions (width, frequency, period). To understand the behavior of internal ions and dipoles in the cross-linked PVP insulating layer, we measured the frequency-dependent capacitance. Interestingly, the capacitance decreased as the frequency increased, suggesting that internal ions could be easily influenced by electrical bias in the cross-linked PVP electrolyte, forming an EDL layer. These findings suggest that the cross-linked PVP/ZnON-based transistor could potentially serve as a significant synaptic transistor component in artificial intelligence technology.
(Invited) Understanding the Photochemistry of Perovskites for Photovoltaics
Authors: Davies Matthew Lloyd , Péan Emmanuel , Rodriguez Rodrigo Garcia , Kalyva Pavlina , Doolin Alex , Charles Rhys , Villalobos Karen Valadez
Published: December 2024

Thanks to their high absorption coefficient and ideal band-gap [1], lead halide perovskite materials are good candidates for the next generation of solar cells with an impressive certified power conversion efficiency of >26% [2]. However, the development of perovskite based solar cells is impeded, in some architectures, by obstacles including degradation of the perovskite layer by light, oxygen, and moisture. Photoluminescence (PL) is a measure of photoexcited carrier radiative recombination and is thus a great tool for studying charge carrier processes in solar cells as the later operates through the absorption of light. However, measuring the steady state and time-resolved photoluminescence (PL) of perovskite thin-films is not as straightforward as initially thought, highlighting the sometimes-surprising nature of these materials. [3-5] This has implications for the use of these materials in photovoltaics and LEDs. We will discuss our utilisation of PL studies to understand the stability and performance of perovskite materials. The impact of the incorporation of nanomaterials into perovskite devices will be discussed along with the opportunities and challenges this affords in terms of sustainability and performance. We will discuss the work of The Applied Photochemistry Group at the SPECIFIC Innovation and Knowledge Centre, Swansea University, which aims to develop an understanding of the photostability and photochemistry of materials and devices to advance performance, sustainability, and design for circular economy.

Yang, WS; Park, BW; Jung, EH; Jeon, NJ; Kim, YC; Lee, DU; Shin, SS; Seo, J; Kim, EK; Noh, JH; Seok, SI. Science, 2017, 356(6345), 1376-1379.

Best Research-Cell Efficiency Chart | Photovoltaic Research | NREL. [Online].

Péan, EV; De Castro, CS; Davies, ML. Materials Letters, 2019, 243, 191-194.

Péan, EV; Dimitrov, S; De Castro, CS; Davies, ML. Phys. Chem. Chem. Phys., 2020, 22, 28345-28358.

Péan, EV; Davies, ML. J. Chem. Inf. Model. 2023, 63, 15, 4477–4482
(Invited) Development of High-Performance Sn Based Halide Perovskite Transistors
Authors: Reo Youjin , Noh Yong-Young
Published: December 2024

Developing high-mobility p-type semiconductors that can be grown using cost-effective scalable methods at low temperatures, has remained challenging in the electronics community for the integration of complementary electronics with the well-developed n-type metal oxide counterparts. Tin (Sn2+) halide perovskites emerge as promising p-type candidates but suffer from low crystallisation controllability and high film defect density, which result in uncompetitive device performance. In this talk, I would like to introduce a general overview and recent progress of our group of p-type Sn-based metal halide perovskites for the application of field-effect transistors (FETs). In the first part of the talk, I will mainly address inorganic perovskite thin-film transistors with exceptional performance using high-crystallinity and uniform cesium-tin-triiodide-based semiconducting layers with moderate hole concentrations and superior Hall mobilities, which are enabled by the judicious engineering of film composition and crystallization. The optimized devices exhibit high field-effect hole mobilities of over 50 cm2 V−
1 s−
1, large current modulation greater than 108, and high operational stability and reproducibility [1,2]. In the second part of the talk, I will introduce A-site cation engineering method to achieve high-performance pure-Sn perovskite thin-film transistors (TFTs). We explore triple A-cations of caesium-formamidinium-phenethylammonium to create high-quality cascaded Sn perovskite channel films, especially with low-defect phase-pure perovskite/dielectric interface. As such, the optimized TFTs show record hole mobilities of over 70 cm2 V−
1 s−
1 and on/off current ratios of over 108, comparable to the commercial low-temperature polysilicon technique level [3]. The p-channel perovskite TFTs also show high processability and compatibility with the n-type metal oxides, enabling the integration of high-gain complementary inverters and rail-to-rail logic gates.

References

Liu, Y.-Y. Noh et al, Nature Electronics 5, 78-83 (2022).

Liu Y.-Y. Noh et al, Nature Electronics 6, 559-571 (2023).

H. Zhu, Y.-Y. Noh et al, Nature Electronics 6, 650-657 (2023).
(Invited) Van Der Waals Heterostructures and Superlattices: Boundless Opportunities at Bondless Boundaries
Authors: Duan Xiangfeng
Published: December 2024

The advent of two-dimensional atomic crystals and van der Waals heterostructures (vdWHs) has catalyzed a bonding-free strategy for constructing heterostructures beyond the limits of traditional epitaxial heterostructures. In this talk, I start with a brief overview of the broad opportunities presented by exploring vdW interactions for the heterogeneous integration of diverse heterostructures with pristine electronic interfaces. I will then focus on our recent efforts in synthesizing and investigating a new family of vdW superlattices (vdWSLs) consisting of alternating crystalline atomic layers and self-assembled molecular layers of designable chemical compositions and structural motifs. I discuss how we may use the intercalated molecular layers to tailor the electronic and optical properties of various 2DACs, and particularly highlight a unique class of chiral molecular intercalation superlattices hosting exhibit robust chiral-induced spin selectivity and elusive chiral superconductivity. With the versatile molecular design and modular assembly strategies, the 2D-molecular vdWSLs allow boundless flexibility for weaving distinct building constituents into artificial solids with designable chemical modulation, structural topology and 3D potential landscape. It opens unprecedented ways to tailor the electronic, optical and quantum properties, thus defining a rich material platform for diverse emerging technologies.
(Invited) Post-Synthetic Modulation of 2D Semiconductors by Organic Materials
Authors: Kiriya Daisuke
Published: December 2024

Modulation of materials is crucial for developing the physicochemical properties and applying them to devices. For transistors, the alignment of energy levels is critical; therefore, the corresponding modulation of carrier concentrations and material phases is a fundamental issue. In this talk, I will focus on the modulation of 2D semiconductors, known as transition metal dichalcogenides (TMDCs), to modulate electronic properties by interfacing with organic materials.

About a decade ago, we demonstrated molecular doping to a TMDC material, MoS2, to modulate the carrier concentration effectively and achieve a degenerately doped level [1]. Various molecules come out after the work. I would discuss the modulation of carrier concentrations of bulk and monolayer MoS2 by interfacing with organic materials from the point of transport behaviors and sensor applications [2].

In addition to the carrier modulation, we are tackling the modulation of phases of TMDCs. The usual semiconductive phase is known as 1H or 2H phase in the case of MoS2. If we can convert the crystalline phase to 1T/1T' phases, it would be interesting to apply it to electronics as a metallic material or quantum devices. Since the 1H and 2H phases are thermodynamically stable, it is not easy to convert MoS2 to 1T/1T' phases. I will show our current state of modulating the phases by applying chemical techniques.

[1] D. Kiriya, et al., Air-stable surface charge transfer doping of MoS2 by benzyl viologen, J. Am. Chem. Soc. 2014, 136, 7853.

[2] K. Matsuyama, et al., Metallic transport in monolayer and multilayer molybdenum disulfides by molecular surface-charge transfer doping, ACS Appl. Mater. Interfaces, 2022, 14, 8163; A. Fukui, et al., Unusual selective monitoring of N,N-dimethylformamide in a two-dimensional layered field-effect transistor, ACS NANO, 2023, 17, 14981.
(Invited) Exploiting Near-Infrared Light for Theranostics
Authors: Vetrone Fiorenzo
Published: December 2024

Since first reported, luminescent rare earth doped nanoparticles have attracted a great deal of interest. In the last decade, however, the field has rapidly taken off, progressing from the basic understanding of the photophysical properties governing their nanoscale luminescence, particularly upconversion, to their use in a plethora of applications, with considerable focus in biology and medicine. This interest stems primarily from the ability to stimulate these luminescent nanoparticles with near-infrared (NIR) light as well as their diverse emission wavelengths spanning the UV to the NIR. Therefore, with a single NIR excitation wavelength, it is possible to observe higher energy luminescence, known as upconversion, or single photon NIR emission (known as down-shifted luminescence). The former upconversion process proceeds through the sequential absorption of multiple NIR photons through the long-lived 4f electronic energy states of the tri-positive rare earth ions. As a result, upconversion is several of orders more efficient than conventional multiphoton absorption processes. This is especially interesting for applications in theranostics (therapy + diagnostics on the same platform) where the upconverted light can be used to trigger another light activated modality (therapy) while the NIR luminescence can be used for bioimaging and nanothermometry (diagnostics). Here, we present our work on the synthesis and development of various NIR excited (and emitting) core/shell rare earth doped nanostructures/nanoplatforms and demonstrate how their various emissions could be harnessed for applications in biology and nanomedicine.
(Invited) Nanoscale Ferroelectric Nitrides for Next Generation Electronics and Quantum Photonics
Authors: Mi Zetian
Published: December 2024

The incorporation of rare earth elements such as scandium (Sc) can transform conventional III-nitride semiconductors to be ferroelectric. This new class of ferroelectric nitride semiconductors can be seamlessly integrated with the well-established III-nitride and Si electronics with promising applications in memory and logic devices as well as high power, high frequency, and high temperature electronics. Moreover, ferroelectric nitrides exhibit significantly enhanced piezoelectric and nonlinear optical response compared to AlN, which makes it attractive for high frequency resonators and filters and nonlinear optical processes. In this talk I will present recent advances of nanoscale ferroelectric III-nitride semiconductors, including molecular beam epitaxy, structural, optical, electrical, and ferroelectric properties, as well as their emerging electronic and photonic device applications.
(Invited) Energy Intelligent Computing Devices Based on 2D Materials
Authors: Yang Heejun
Published: December 2024

Despite the long and crucial role of traditional solid-state physics for current silicon-based technologies, next generation neuromorphic, non-volatile memory, and energy devices that are key components in the era of the internet of things (IOT) require novel working principles with quantum physics emerging in low-dimensional materials1-4. The main research direction for the future devices is to realize ‘ultralow device operation energy’, ‘ultrahigh device operation speed’, and ‘large-scale device integration (up to 1015)’, which calls for exploring diverse quantum phenomena in low dimensional device components5,6. In this talk, I will present some of our recent efforts1-7 to establish new device physics for energy intelligent devices, which could be a milestone for the promising future devices. In particular, dynamic convolution neural network, phase transition and other intriguing quantum physics in two-dimensional (2D) materials will be discussed along with logic device, neuromorphic computing, and energy device applications.

Reference

H. Yang et al. Graphene Barristor, a Triode Device with a Gate-Controlled Schottky Barrier,
Science
336, 1140 (2012)

S. Cho et al. Phase Patterning for Ohmic Homojunction Contact in MoTe2.
Science
349, 625 (2015)

D. H. Keum et al. Bandgap opening in few-layered monoclinic MoTe2.
Nature Physics
11, 482 (2015)

H. Yang et al. Structural and quantum-state phase transition in van der Waals layered materials.
Nature Physics
13, 931 (2017)

L. Sun et al. Self-selective van der Waals heterostructures for large-scale memory array.
Nature Communications
10, 3161 (2019)

S. Zheng et al. Resonant tunneling spectroscopy to probe the giant Stark effect in atomically-thin materials.
Advanced Materials
32, 1906942 (2020)

L. Sun et al. In-sensor Reservoir Computing for Language Learning via Two-dimensional Memristor.
Science Advances
7, eabg1455 (2021)
Modulating Electronic Properties through Synthesis of Single-Layer Metallic Janus Crystal NbSSe
Authors: Sailus Renee , Tongay Sefaattin
Published: December 2024

Janus crystals represent a family of 2D materials with structures that feature a metal cation between two different atomic species on the top and bottom faces. This unique structure with its broken mirror and inversion symmetry enables a host of fascinating quantum effects including formation of an internal electric field at the monolayer-limit, unique topological phases, and colossal polarization field. In particular, the metallic Janus crystal NbSSe is predicted to be a stable 2D polar metal of the kind theorized by Anderson and Blount and offers possible applications in nanoscale ferroelectric devices. In this talk I will introduce advances in realizing synthesis of metallic 2D Janus crystal NbSSe at Arizona State University. NbSSe is experimentally demonstrated via a surface-limited technique of plasma-driven atomic replacement at the surface to convert parent TMD crystals 1H-NbSe2 and 1H-NbS2 into 1T-NbSSe. Microscopic, topographical, and spectroscopic techniques are carried out to elucidate the structural transformation, air- and photo-stability, and electronic properties attributed to metallic Janus NbSSe1-6.

References

Anderson PW, Blount EI. 1965. Symmetry considerations on martensitic transformations: “Ferroelectric” metals? Phys. Rev. Lett. 14(7):217–219

Y. Qin, M. Sayyad, A. R.-P. Montblanch, M. S. G. Feuer, D. Dey, M. Blei, R. Sailus, D. M. Kara, Y. Shen, S. Yang, A. S. Botana, M. Atature, S. Tongay, Reaching the Excitonic Limit in 2D Janus Monolayers by In Situ Deterministic Growth. Adv. Mater.2022, 34, 2106222.

D. B. Trivedi, G. Turgut, Y. Qin, M. Y. Sayyad, D. Hajra, M. Howell, L. Liu, S. Yang, N. H. Patoary, H. Li, M. M. Petrić, M. Meyer, M. Kremser, M. Barbone, G. Soavi, A. V. Stier, K. Müller, S. Yang, I. S. Esqueda, H. Zhuang, J. J. Finley, S. Tongay, Room-Temperature Synthesis of 2D Janus Crystals and their Heterostructures. Adv. Mater.2020, 32, 2006320.

Fei, Z., Zhao, W., Palomaki, T.A. et al.Ferroelectric switching of a two-dimensional metal. Nature
560, 336–339 (2018). https://doi.org/10.1038/s41586-018-0336-3

Zhou, W. X. and Ariando Ariando. “Review on ferroelectric/polar metals.” Japanese Journal of Applied Physics 59 (2020).

Yagmurcukardes, M.; Qin, Y.; Ozen, S.; Sayyad, M.; Peeters, F. M.; Tongay, S.; Sahin, H., Quantum properties and applications of 2D Janus crystals and their superlattices. Applied Physics Reviews
2020,
7 (1).

Figure 1
(Invited) Metal Oxide Nanowire Array to Overcome Odor Sensing Limits
Authors: Nagashima Kazuki
Published: December 2024

Toward developing advanced cyber-physical system (CPS), interest for a molecular recognition electronics is rapidly increasing for collecting chemical information in our daily life. Among various sensor technology, artificial olfactory sensor targeting on chemical data collection of odor is growing research field due to its promise in wide applications for non-invasive medical diagnosis, environmental monitoring, factory automation, security, smart agriculture, etc. In such applications, a lack of molecular sensing system having both material robustness and capability of molecular discrimination in complex mixtures has been a critical issue for the long-term collection of chemical information. Inorganic nanowires, especially for metal oxide nanowires, are a class of promising materials to overcome such issues due to their excellent material robustness in air and huge surface-to-volume ratio beneficial for effectively capturing and concentrating volatile molecules on their surface. Although a highly sensitive electrical detection of volatile molecules has been demonstrated using semiconducting nanowires up to date, poor understanding and design capability of molecule-to-surface interactions on nanowire surface have substantially limited their performance in artificial olfactory sensor systems which require molecular discrimination in complex mixtures.

In this presentation, we demonstrate that designing a coordination structure of ionic species at nanowire surface is of critical importance to control the adsorption, reaction and desorption properties of volatile molecules. The enhanced sensing performance and the molecular selective adsorption property of nanowire were successfully achieved as the results of designed surface coordination structure. In addition, molecular filter/molecular transport controller using nanowire array integrated with sensor device is conceptualized as novel artificial olfactory sensor system to discriminate molecules in complex mixture beyond the previous sensing limits.

References: ACS Sens.
7, 534 (2022) / Chem. Commun.
58, 6377 (2022) / Chem. Lett.
51, 424 (2022) / ACS Sens.
7, 151 (2022) / Chem. Sci.
12, 5073 (2021) / ACS Appl. Nano Mater.
3, 10252 (2020) / Commun. Mater.
1, 58 (2020) / Nano Lett.
20, 599 (2020) / Nano Lett.
19, 2443 (2019)
(Invited) 3D Oriented Metal–Organic Framework Dmof-1 Thin Films Functionalized with Azobenzene as Photo-Stimuli-Responsive Materials
Authors: Klokic Sumea , Amenitsch Heinz
Published: December 2024

Profound knowledge on the structural transformations of photo-switchable Metal-Organic Framework films is fundamental to optimize their switching performance and to use them as stimuli-responsive materials.

In an epitaxial oriented DMOF-1-on-MOF film system [1] comprising azobenzene in the DMOF-1 pores (DMOF-1/AB) we studied the temporal evolution of the structural transformation after photo excitation. Therefore we employed time-resolved Synchrotron Grazing Incidence Wide-Angle X-Ray Scattering [2] and infrared measurements to track in depth the structural response of the DMOF-1/AB film upon altering the length of the azobenzene molecules by photo-isomerization (trans-to-cis, 343 nm; cis-to-trans, 450 nm). The DMOF-1/AB response occurred fully reversible and over several switching cycles by cooperative photo-switching of the entire oriented film within seconds [3].

For a deeper understanding of the switching behavior, we further investigated (i) the influence of substituting the terephthalic acid linkers in DMOF-1 with chloro-functionalized derivatives (Cl-DMOF-1) and (ii) enlarging its crystallite size with increasing growth times. Here, we could show that Cl-DMOF-1 reduces the structural flexibility, leading directly to a significantly slower response. In contrast, small crystallite sizes show entirely rigid frameworks (10-60 min) and more flexible ones with prolonged growth times (90 - 270 min) [4].

This work opens possibilities to tailor the functional behavior of light triggered mechanical storage systems e.g. [5].

References:

[1] M. Linares‐Moreau, L. A. Brandner, T. Kamencek, S. Klokic, F. Carraro, K. Okada, M. Takahashi, E. Zojer, C. J. Doonan and P. Falcaro, Adv. Mater. Interfaces, 2021, 8, 2101039.

[2] ) M. Burian, B. Marmiroli, A. Radeticchio, C. Morello, D. Naumenko, G. Biasiol, H. Amenitsch, J. Synchrotron Rad. 2020, 27, 51.

[3] S. Klokic, D. Naumenko, B. Marmiroli, F. Carraro, M. Linares-Moreau, S. D. Zilio, G. Birarda, R. Kargl, P. Falcaro and H. Amenitsch, Chem. Sci., 2022, 13, 11869–11877.

[4] S. Klokic, B. Marmiroli, D. Naumenko, G. Birarda, S. Dal Zilio, M. de J. Velásquez-Hernández, P. Falcaro, L. Vaccari and H. Amenitsch, CrystEngComm, 2024, DOI: 10.1039/D4CE00221K

[5] J. Wieme, S. M. Rogge, P. G. Yot, L. Vanduyfhuys, S.-K. Lee, J.-S. Chang, M. Waroquier, G. Maurin and V. Van Speybroeck, J. Mater. Chem. A., 2019, 7, 22663–22674.
(Invited) Advanced Nanoengineering for Sustainable Energy Technologies
Authors: Selopal Gurpreet Singh , Shanmugasundaram Kokilavani , Madhu Swedha , Vidal François , Zhao Haiguang
Published: December 2024

Semiconductor nanocrystals, so-called quantum dots (QDs), are considered promising building blocks to fabricate high-performing emerging optoelectronic technologies such as solar energy conversion devices [i.e., photovoltaics, photoelectrochemical (PEC) cells for clean fuel production, luminescent solar concentrators (LSCs) etc.], QDs-light emitting diode (QLED), nanothermometers and bio-sensors, due to their size/shape/composition-dependent promising electronic and optical properties associated with the “quantum confinement” effect. However, the performance of QDs-based solar energy conversion devices is still lower than the expected theoretical value, which is mainly associated with the narrow light harvesting range, slow charge injection/transfer rate from QDs to scavengers and fast non-radiative carrier recombination within the QDs and QDs/metal oxide/electrolyte interface. To address these challenges, surface and interface engineering of QDs in which the surface of the QD core is passivated with the shell layer of different thicknesses compositions and structures has been shown to be an effective approach. In the talk, nanoengineering of core/shell QDs with variable shell thickness and interfacial engineering will be discussed. Then the effect of different shell thicknesses, compositions, and interfacial layers of core/shell QDs to improve the optoelectronic properties in terms of broadening the absorption spectrum and efficient carrier dynamics compared to the control QDs will be presented. Finally, the optimized core/shell QDs implemented as a light harvester in photovoltaics and PEC systems for green hydrogen production and possible future directions will be presented and discussed.

References

[1] I. Moreels et al., ACS Nano, 2011, 5, 2004; [2] A. J. Nozik et al., Chem. Rev., 2010, 110, 6873; [3] A. Pandey et al., Science, 2008, 322, 929; [4] G. S. Selopal et al., Adv. Funct. Mater., 2020, 30, 1908762; [5] G. S. Selopal et al., Nanoscale Horizons, 2019, 4, 404-414;[6] I. Mora-Seró et al., Acc. Chem. Res., 2009, 42,1848.
(Invited) Investigating New Avenues for the Bulk Single Crystal Growth of BN
Authors: Metzger Florian , Dooley Jacob , Valenzuela Jonny , Sherpa Tenzin , Stoddard Nathan , Landskron Kai , Pimputkar Siddha
Published: December 2024

Boron nitride (BN) is a fascinating ultra-wide bandgap semiconductor offering extreme material properties that can be leveraged in a range of potential applications including (opto-)electronic and quantum devices. Availability of high-quality, large-area and volume, single-crystal material would provide a significant boon to the community facilitating or enabling development of devices. BN has been successfully grown using high pressure, high temperature presses and precipitation from a solvent on the order of a few millimeters. While these methods have yielded high-quality material, scaling of these approaches is challenging motivating the search for additional bulk synthesis methods. This talk will present foundational work being performed in the pursuit of bulk BN growth using two industrial scalable methods: the ammonothermal method and a flux-based approach.

The ammonothermal method utilizes supercritical ammonia at temperatures and pressures around 400—600 °C and 100—250 MPa, respectively. One or more mineralizers are added to the solution to enhance the solubility of BN. This talk will demonstrate temperature-dependent solubility of BN in basic ammonothermal solutions containing alkali [1] and/or alkaline earth metals. Initial crystal growth experiments were performed using sodium as the mineralizer yielding the spontaneous nucleation and growth of sub-mm sized hexagonal and rhombohedral BN.

The flux-based method uses a solvent exhibiting exceptionally high solubility of nitrogen and boron. A dedicated growth system has been developed and initial growth runs have demonstrated the solubility and growth of BN from solution. Preliminary growth campaigns have successfully demonstrated the growth of ~ >0.1 mm sized BN crystals after 1-2 days.

This work has been supported by NSF DMR 1832824, NSF CAREER 2046468, ARL DEVCOM UWBG RF Electronics Center, and Lehigh Startup Funds.

[1] Dooley, J., Stoddard, N., Landskron, K. & Pimputkar, S. On the solubility of boron nitride in supercritical ammonia-sodium solutions. J. Cryst. Growth
621, 127381 (2023). doi: 10.1016/j.jcrysgro.2023.127381
Nanoconfined Lanthanum Hydride Nanoconfinement in Functionalized Carbon Hosts
Authors: Shivanna Mohana , Elmslie Timoth , Duwal Sakun , Spataru Catalin , Piontkowski Zak , Teprovich Joseph , Allendorf Mark D. , Sharma Peter , Stavila Vitalie
Published: December 2024

Metal hydrides with a high hydrogen content have long been considered for materials-based hydrogen storage and but are now attracting attention as potential high-temperature superconductors.1 Recently, we showed that cryo-milling lanthanum improves hydrogen diffusion, yielding a higher hydrogen-to-metal ratio of lanthanum hydride up to LaH4.2 Another strategy for improving the thermodynamics and hydrogen desorption kinetics of metal hydrides is nanoconfinement within porous hosts.3,4 However, this has not previously been achieved for lanthanum hydride (LaHx) due to the difficulty of isolating nanoparticles of La or La-hydrides.

In this work we demonstrate that LaHx can be infiltrated into two porous carbons: nitrogen-doped CMK-3 (NCMK-3) and undoped CMK-3, both with average pore size 4-5 nm. Transmission electron microscopy (TEM) images reveal that LaHx species are distributed uniformly throughout these hosts in NCMK-3 and CMK-3 with rod and spherical morphologies, respectively. X-ray absorption spectroscopy (XAS) and X-ray photoelectron microscopy (XPS) were used to probe the coordination environment of the LaHx species and composition lanthanum and nitrogen. Sieverts measurements indicate that LaHx@NCMK-3 desorbs up to 0.7 wt % hydrogen, which is higher than the non-nitrogen functionalized CMK-3 (0.5 wt%H). Density Functional Theory (DFT) and ab initio molecular dynamics (AIMD) calculations predict that host-guest interaction energies are favorable for porous carbon with pyridinic, pyrolic, or pyridonic nitrogen defects on a graphene surface, consistent with experimental data. Moreover, high-pressure experiments were conducted to understand the tunability of hydrogen content in presence of ammonia borane as a hydrogen source. These revealed that the as-prepared materials underwent an increase in H:La ratio from 1.5 to 3.0 with pressure. Our results demonstrate that nitrogen-doped nanoporous carbons can confine lanthanum hydrides, favor higher H:La ratios, and could serve as a platform for developing superconducting materials at relatively low pressures (compared with diamond anvil cells) and temperatures.

-W. Guan, R. J. Helmley, V. Viswanathan Combining pressure and electrochemistry to synthesize superhydrides PNAS
2021, 118, e2110470118.

Duwal, V. Stavila, C. Spataru, M. Shivanna, P. Allen, T. Elmslie, T. C. Seagle, J. Jeffries, N. Velisavljevic, J. Smith, P. Chow, Y. Xiao, Y. Meng, M. Somayazulu, P. A. Sharma Enhancement of hydrogen absorption and hypervalent metal hydride formation in lanthanum using cryogenic ball milling Phys. Rev. Mater., 2024, submitted.

Stavila, S. Li, C. Dun, M. A. T. Marple, H. E. Mason, J. L. Snider, et al.
Angew. Chem. Int. Ed.
2021,
60, 25815-25824.

Schneemann, L. F. Wan, A. S. Lipton, Y.-S. Liu, J. L. Snider, A. A. Baker, et al. ACS Nano
2020,
14, 10294-10304.
Effects of Anion or Cation Structures on the Interaction of Ionic Liquid with Cu3(BTC)2 Metal-Organic Frameworks
Authors: Koseki Kaito , Zheng Yumeng , Kinoshita Kentaro
Published: December 2024

Metal-organic frameworks (MOFs) are a class of porous materials with highly periodic nanopores and enormous specific surface area, which allow us to achieve gas adsorption and catalytic applications superior to those based on conventional porous materials [1]. However, the structural degradation due to moisture absorption and fragility in many MOFs led to challenges for practical application. We have found a solution to inhibit this moisture degradation by filling ionic liquid (IL) into the nanopores of MOF; the composite materials are referred to as IL@MOF. In addition, in IL@MOF, it was also clarified that the fragility was improved while keeping the crystal structure [2]. However, the reason is still unclear.

In this study, we focus on the interaction of IL with MOF and the effects of IL types on the crystal structure of MOF. IL@MOF samples were prepared by filling imidazolium-based [Cnmim][Tf2N] with different cation alkyl side chain lengths (n = 2, 4, 8) into single crystal HKUST-1 MOF (Cu3(BTC)2), which was synthesized by the solvothermal method [3]. Here, the sample was given a name according to the cation alkyl side chain length, i.e., Cu3(BTC)2 filled with [C2mim][Tf2N] is named C2@ Cu3(BTC)2. X-ray photoelectron spectroscopy (XPS) was used to analyze the binding energy (B.E.) of MOF frames, and X-ray diffraction (XRD) was used to measure the lattice spacing of MOF.

XPS spectra of C 1s, O 1s, Cu 2p3/2 for Cu3(BTC)2 and C4@Cu3(BTC)2 are presented in Figs. 1(a), (b), and (c). The XPS spectra were corrected so that the peaks corresponding to the C–C (285 eV) for both Cu3(BTC)2 and C4@Cu3(BTC)2, confirmed by peak separation, became the same, as shown in Fig. 1(a). It was found that the B.E. of Cu 2p3/2 and O 1s decreased with IL filling. The decrease in B.E. from B.E. of Cu3(BTC)2 was larger for shorter alkyl side chain lengths (Fig. 1(d)). This may be attributed to the coordination of the anions of the ILs to Cu, which effectively decreased the oxidation number of Cu. The decrease in the oxidation number of Cu is expected to reduce the Cu–O interactions and elongate the Cu–O bonds. This was verified by the result of XRD measurement shown in Fig. 1(e), indicating that the lattice spacing of the (222) plane of Cu3(BTC)2 increased after IL filling. The increase in the lattice spacing by IL filling is larger for shorter alkyl side chain lengths. These results suggest that IL filling elongates the Cu–O bonds in Cu3(BTC)2, and that the effect is more significant for shorter side chain lengths. We will discuss the IL species dependence of the MOF framework modulation including anions in detail in the presentation.

[1] YU, Jia, et al., Materials Horizons, 2017, 4.4: 557.

[2] S. G. Koh, et al., J. Phys. Chem. C 2022, 126, 6736

[3] L. Li, F. Sun, J. Jia, T. Borjigina, and G. Zhu, CrystEngComm, 2013, 15, 4094.

Figure 1
Development of New Light-Dimming Film Using Black Electrochromic Inks
Authors: Taguchi Ryo , Tajima Kazuki , Kubota Takashi , Watanabe Hiroshi , Kamei Tadayoshi , Fukui Michiaki
Published: December 2024

Windows serve the purpose of allowing people to see outside from inside. However, excessive sunlight and heat can enter through windows, disrupting the indoor thermal environment. In the case of vehicles, heat can accumulate quickly in the enclosed space, and temperatures on dashboards can exceed 80°C in summer, jeopardizing the comfort and safety of passengers and drivers without proper heat shielding measures. Our research group is developing a new light-dimming film that can be used for automotive applications. This light-dimming film uses electrochromic principles to produce color change and heat shielding properties through electrochemical effects caused by the application of voltage. This light-dimming film can be fabricated using a wet coating process, which is expected to be highly productive, low-cost, and easily applicable to large-area applications. We are developing a complementary device by combining Prussian blue (PB)-type complex nanoparticles and tungsten oxide (WO3) nanoparticles (NPs). In this prototype device configuration, the electrochemical response produces a colorless transparent state and a dark blue color change, and when colored, the transmittance in the near-infrared region can be reduced to 1% or less. When applied to automobile windows, the performance of cutting heat rays contained in sunlight under hot weather can reduce the air conditioning load, which is expected to reduce fuel consumption or electricity costs in EV vehicles. On the other hand, this dark blue colored state has design issues such as matching with car body color and luxury. To solve these issues, this research is exploring and developing new black electrochromic material such as CuO nanoparticles, etc. In PRiME, we report on the progress in the development of the black electrochromic materials.
Improved Functionality of Ultrafast Responsive Electrochemiluminescent Device with DNA/Ru(bpy)3
2+ Hybrid Film and Various Electrolyte Compositions
Authors: Ozawa Ryuki , Nakatani Hiroki , Tachikawa Takashi , Nakamura Kazuki , Kobayashi Norihisa
Published: December 2024

Electrochemiluminescence (ECL), a light-emitting phenomenon induced by electrochemical redox reactions, has potential applications in lightweight and flexible light-emitting devices. Previously, an ultrafast ECL response of <100 μs was successfully achieved under application of alternating current voltage by using a DNA-modified electrode including Ru(bpy)3
2+, an orange ECL material. In this study, we investigated effect of electrolyte composition on the fast responsive ECL in the DNA/Ru(bpy)3
2+ hybrid film-based ECL device. As a result, the ECL intensity and lifetime of ECL were improved by introducing additional Ru(bpy)3
2+ into the electrolyte solution. The increase concentration of Ru(bpy)3
2+ inhibited dissolution of aggregated part formed on DNA/Ru(bpy)3
2+ hybrid film and increase in the amount of reactive charge in the aggregated part. Furthermore, we introduced blue-luminescent 9,10-diphenylanthracene (DPA) into the electrolyte solution of the ECL device consisting of DNA/Ru(bpy)3
2+ hybrid film. Consequently, blue ECL from DPA was obtained from the DNA/Ru(bpy)3
2+ hybrid electrode at lower applied voltage than that required to induce the redox reactions of DPA itself. This lower-voltage-drivable blue ECL was attributed to triplet–triplet energy transfer from Ru(bpy)3
2+ in the DNA/Ru(bpy)3
2+ hybrid electrode followed by a triplet–triplet annihilation upconversion reaction of DPA in the electrolyte solution. Moreover, ultrafast-response, electrochemically triggered blue luminescence from DPA was successfully observed.
High Performance and Durable Electrochromic Device of Fe(II)-Based Metallo-Supramolecular Polymer for Smart Electrochromic Window Application
Authors: Roy Susmita , Mondal Sanjoy , Roy Susmita
Published: December 2024

A durable semi-solid-state electrochromic device (ECD) of Fe(II)-based metallo-supramolecular polymer (polyFe) was fabricated by incorporating Nickel hexacyanoferrate (NiHCF) as a charge-balancing layer. The ECD exhibited reversible blue-violet to bleached optical transition in a very low potential window of +1.2V to +0.2V. The low operating potential window enabled ultra-high cycle stability and improved optical memory of the ECD. For the further improvement of the EC properties, it was revealed that the optimization of the film thickness of the polyFe and NiHCF is critical to maintaining the charge balance between the working and counter electrodes. At last, the cyclic stability for the repeated color changes over 100,000 cycles were achieved. This finding will help engineers and scientists to fabricate a low-voltage-driven, long-lasting ECD for real-life application in smart electrochromic window technology.
Electrochromic Devices with Metallosupramolecular Polymers
Authors: Higuchi Masayoshi
Published: December 2024

Metallosupramolecular polymers (MSPs) are a kind of coordination polymers and have one-dimensionally successive metal complex moieties. Our group found electrochromic (EC) properties of MSPs. In this presentation I report recent progress on synthesis of MSPs and fabrication of EC devices (ECDs) with MSPs. As a new polymer, we developed Zn-based MSP with EC and electrofluorochromic (EFC) dual switching properties. Regarding the synthetic method, we succeeded in electropolymerization of MSP. We also developed flexible multicolor rewritable paper coated with MSPs.
Probing CO2 Reduction Chemistry Under Operando Condition
Authors: Liu Bin
Published: December 2024

Noble-metal and transition-metal based materials have been demonstrated as promising catalysts for selective electrochemical CO2 reduction reaction (CO2RR), however, neither the detailed structures of catalytic intermediates nor the key surface species have been unambiguously identified. In this work, a series of single transition-metal atom catalysts with well-defined structures were developed as model systems to explore the electrochemical CO2RR chemistry. Employing a combination of operando X-ray absorption spectroscopy, attenuated total reflectance surface enhanced infrared absorption spectroscopy, Raman spectroscopy and Mössbauer spectroscopy, we successfully captured the dynamic evolution of the catalytic centers during the CO2RR process.
Enhancing Energy Solutions and Environmental Remediation: Piezocatalysis in Ferroelectric High-Entropy Oxides and 2D Materials
Authors: Wu Jyh-Ming
Published: December 2024

Hydrogen is the most abundant element on Earth, and it is a safe and efficient source of energy. Through electrocatalysis and photocatalysis water molecules can be split into O and H2, which can then be used for fuel. This has been widely studied as a promising approach to reduce CO2 emissions and reliance on fossil fuels. A solar-assisted electrochemical process that generates H2 without toxic byproducts is being investigated. Solutions involving the remediation of water pollutants, water splitting, and clean energy alternatives have been widely investigated. However, most semiconducting photocatalysts are not very efficient when used in water-based solutions, because they have a low quantum yield. This talk will report how the piezocatalyts and flexocatalysts can proceed with electrochemical reactions for highly efficient wastewater treatment and hydrogen production. Considering the piezophototronic effect in the visible range, we combined a ferroelectric component with a high entropy oxide (HEO) compound, which can significantly enhance the charge transfer of the HEO's surface, enhancing the catalytic activity (Figure 1). Theoretical calculations revealed that a ferroelectric component could create an inner electric field at interfacial phase boundaries and effectively moderate free carriers, strengthening the charge separation in the ferroelectric HEO catalyst. When an external mechanical force was coupled with photoirradiation, the photoinduced charge separation coupled with piezoelectric polarization enhanced the charge transport in trapping sites. In this talk, I will provide an overview of High Entropy Oxide (HEO) ferroelectric catalysts, along with advancements in piezocatalysts within 2D materials and ferroelectric domains. The concepts presented will pave the way for designing next-generation piezo-photocatalysts.

References

Y. T. Lin, S. N. Lai, J. M. Wu*, Advanced Materials 32 (34), 2002875, 2020.

SC Chang, HY Chen, PH Chen, JT Lee, JM Wu*, Applied Catalysis B: Environmental 324, 122204, 2023.

Figure 1
Investigation of Phase Transition for BaTiO3 Nanoparticles By High-Temperature X-Ray Diffraction
Authors: Katsumata Tetsuhiro , Takashima Hiroshi , Sue Kiwamu
Published: December 2024

A piezocatalyst is a piezoelectric utilized to drive chemical redox reactions. The piezoelectric produces electro charges (electrons and holes) by applying mechanical stress, and these charged charges assist in the chemical redox reactions. A nanoparticle of a typical ferroelectric compound BaTiO3 (nano-BTO) is one of the candidates of the piezocatalyst because of the large surface area and and non-toxic. In fact, it has been reported that the decomposition of water is promoted by ultrasonic vibration when the nano-BTO is used as the piezocatalyst[1]. However, the elucidation of the nano-BTO's ferroelectricity from the crystal structure is difficult because the tetragonality is relatively small, and its structure is pseudo-cubic. In this study, we propose a simple elucidation method for the phase transition of nano-BTO using lab-level high-temperature X-ray diffraction. We carefully measured the 200 and 111 reflections of the nano-BTO with 50 nm size, and investigated the variation of the peak width of these diffractions with the temperature using a Rigaku SmartLab X-ray diffractometer and REACTOR-X high-temperature heating system. As a result, the peak width of 200 reflections apparently narrowed above a phase transition temperature, even though the width of 111 reflections was unchanged, as shown in Fig.1. This result indicates that the nano-BTO with 50 nm size is the tetragonal structure at room temperature. In addition, we succeeded in detecting the phase transition for 20nm nano-BTO. Since this method makes it possible to investigate the phase transitions of nano-BTO in simply way, it would be a valuable technique for piezocatalyst research.

Figure 1
Flexo-Phototronic Effect in Centro-Symmetric BiVO4 Epitaxial Films
Authors: Chu Ying-Hao
Published: December 2024

With exciting functionality, topological defects in ferroic systems have attracted significant attention. Under proper design, the emergence of polar domain walls in non-polar ferroelastics enables a flexo-phototronic effect. In this study, we revealed a ferroelastic twin texture with a localized flexoelectric effect in centrosymmetric epitaxial BiVO4 film. Supported by photodeposition and localized photocurrent analysis, we found the flexoelectric effect confined at the domain wall area facilitates photocarrier transport, and the flexo-phototronic mechanism was further supported by dye-degradation and generation of reactive radicals. This work provides new insights into the introduction of flexo-phototronic effects in non-polar materials and sheds light on the use of material inhomogeneity for acquiring multifunctionality.