bluuebunny/crossref_metadata_2025 huggingface dataset:
Unraveling the Nature of Vibrational Dynamics in the Metal Halide Perovskite CsPbI3
Authors: Lavén Rasmus , Fransson Erik , Erhart Paul , Karlsson Maths
Published: December 2024

Metal halide perovskites, such as the all-inorganic perovskite CsPbI3, are widely considered as highly promising for photovoltaic applications. However, fundamental questions surrounding the vibrational dynamics, especially in regard to the nature of dynamics close to the materials' crystallographic phase transitions are not fully understood. In this contribution, we will report studies of the atomic-scale structure and dynamics of CsPbI3, using a combination of inelastic and quasielastic neutron scattering techniques together with molecular dynamics simulations. The results unravel a quasi-harmonic and almost temperature-independent lattice dynamics from 10 K all the way up to the orthorhombic-to-cubic phase transition at around 600 K. In the cubic perovskite phase (T > 600 K) of CsPbI3, the dynamics are, conversely, highly anharmonic and overdamped, which are due to anharmonic rattling motions of the Cs+ ions with the “perovskite cage” and spatially coherent, yet overdamped dynamics of the Pb-I perovskite sub-lattice. Since the overdamping of vibrational dynamics in metal halide perovskites have been suggested to reduce the interaction with charge carriers and hence lead to an increase of the charge carrier lifetime and diffusion lengths, which are critical factors affecting the performance of metal halide perovskites in actual devices, this new insight can be expected to help in the rational design of new metal halide perovskites towards specific applications.
Four-Terminal Double-Junction Solar Cells Consisting of a Mesoscopic Wide-Bandgap Perovskite Solar Cell and an Inverted Narrow-Bandgap Perovskite Solar Cell with Spectral Splitting System
Authors: Ito Kei , Nonomura Kazuteru , Kan Ryota , Tada Keishi , Lin Ching Chang , Kinoshita Takumi , Bessho Takeru , Uchida Satoshi , Segawa Hiroshi
Published: December 2024

The spectral splitting system is one of the hybridization method to convine different solar cells to improve energy conversion efficiency by dividing sunlight into different spectral ranges. This technique is particularly valuable because different materials exhibit distinct spectral responses. By employing multiple types of solar cells optimized for different parts of the solar spectrum, overall panel efficiency can be increased compared to using a single type of solar cell. Implementing this technique requires careful design and engineering to ensure efficient spectral splitting and maximize electricity output from each type of solar cell. The organometal halide perovskite solar cell (PSC) exhibits a wide range of adjustable band gaps depending on its composition. To attain high efficiency in two-junction PSCs, combination of "mesoscopic" Pb-PSC with an "inverted" Sn-Pb mixed PSC is useful approach. In this study, a four-terminal spectral splitting double junction solar cell was fabricated by combining a mesoscopic-structure Pb-PSC and an inverted-structure Sn-Pb PSC, employing a dichroic mirror to split incident light into long and short wavelengths.

In the experimental setup for the wide-bandgap top cell, initial steps involved the fabrication of compact and mesoscopic structure tin oxide layers on an FTO substrate. Subsequently, several wide-bandgap perovskite absorbers were spin-coated. Then, Spiro-OMeTAD was spin-coated onto the absorber layer, followed by thermal evaporation of gold. For the fabrication of the narrow-bandgap inverted PSC, a layer of PEDOT:PSS was spin-coated onto the FTO substrate. Then several narrow-bandgap perovskite absorbers were spin-coated. Finally, fullerene, bathocuproine, and silver were thermally evaporated onto the substrate. Finally, a four-terminal spectral splitting tandem solar cell was fabricated by combining the wide-bandgap mesoscopic structure top cell and the narrow-bandgap inverted structure bottom cell.

J-V measurements conducted at several split wavelengths revealed a photovoltaic conversion efficiency (PCE) of over 20% for the top cell and about 5% for the bottom cell was obtained. However, the result showed that there is still room for improvement in bottom cell performance. As a result, the bandgap of narrow-bandgap perovskite was reduced by adjusting the ratio of tin and lead such as Cs0.025FA0.475MA0.5Sn0.6Pb0.4I3. This adjustment extended the optical absorption region of bottom cell to slightly longer wavelengths, as measured by EQE. Subsequently, the J-V measurements revealed a photovoltaic conversion efficiency of 20.1 % for the top cell and 5.36 % for the bottom cell at the 801 nm split. The total PCE of 25.5 % was obtained, surpassing previous results.
Improvement of Performance of Perovskite Solar Cell By in-Plane Design
Authors: Yoshihara Yuka , Tada Keishi , Nakazaki Jotaro , Awai Fumiyasu , Nonomura Kazuteru , Uchida Satoshi , Segawa Hiroshi
Published: December 2024

Perovskite solar cells (PSCs) have attracted attention as one of the next-generation solar cell. To enhance power conversion efficiency (PCE) of PSCs, a great deal of research has been conducted so far, mainly in the field of material development. However, in-plane cell design for evaluating the performance of PSCs are currently not standardized. In this study, optimization of device structures was investigated for the aim of to minimize charge transfer losses and improve FF and PCE.

The fabrication of perovskite solar cell is as follows; (i) as the electron transport layer (ETL), compact TiO2 and mesoporous TiO2 were deposited on FTO glass substrates by spray coating and spin-coating. (ii) K0.025(Cs0.1FA0.9)0.975PbI3 perovskite was deposited by spin-coating using the anti-solvent method1). (iii) Spiro-OMeTAD was spin-coated as the hole transport layer. (iv) The electrodes were insulated by laser etching. (v) Finally, Au was vacuum-deposited and laser-etched again to fabricate the cell.

Throughout the two laser etching stages in the cell fabrication process, adjustments are made to the shapes of the ETL/perovskite layer/HTL and the Au electrode. Specifically, performance was compared for three patterns of devices; (a) round-shaped generator section and current-collecting bridge, (b) shorter distance of current-collecting bridge, (c) shorter distance of current-collecting bridge and same width of current-collecting bridge as generator section. Photoelectric conversion characteristics was determined based on I-V characteristics measured under quasi-sunlight (AM 1.5, 100 mW/cm2) irradiation. In all cases, the shading mask area was kept constant at 0.18 cm2.

Figure shows images of three patterns of the results of comparing FF from I-V measurements for each device with varying shapes. It can be seen that even PSCs fabricated from the same material exhibit different FF values depending on the cell shapes. PCE and FF were higher in (b) than in (a), with the highest values observed for devices of (c), in which the collector bridge is shortened and the width is increased. In addition, the series resistance (Rs) and shunt resistance (Rsh) were approximated from the slope of the I-V curve. Among the internal resistances, the series resistance (Rs) decreased, leading to an improvement in FF. This is thought to be due to the decrease of series resistance of electron and hole transfer.

Figure 1
Over 5,000 h at 85 °C Thermal Stability of Encapsulated Carbon–Based Multiporous–Layered–Electrode Perovskite Solar Cells
Authors: Tsuji Ryuki , Ito Seigo
Published: December 2024

The key to the practical application of organometal–halide–crystals perovskite solar cells (PSCs) is to achieve thermal stability through robust encapsulation. This paper presents a method to significantly extend the thermal stability lifetime of perovskite solar cells to over 5,000 h at 85 °C by demonstrating an optimal combination of encapsulation methods and perovskite composition for carbon–based multiporous–layered–electrode (MPLE)–PSCs. We fabricated the four types of MPLE-PSCs using two encapsulation structures (over– and side–sealing with thermoplastic resin films) and two perovskite compositions ((5–AVA)x(methylammonium (MA))1–xPbI3 and (formamidinium (FA))0.9Cs0.1PbI3), and analyzed the 85 ºC thermal stability followed by ISOS–D–2 protocol. Without encapsulation, FA0.9Cs0.1PbI3 exhibited higher thermal stability than (5–AVA)x(MA)1–xPbI3. However, encapsulation reversed the phenomenon (that of (5–AVA)x(MA)1–xPbI3 became stronger). The combination of (5–AVA)x(MA)1–xPbI3 perovskite absorber and over–sealing encapsulation effectively suppressed the thermal degradation, resulting in the PCE value at 91.2% of the initial value after 5,072 h. On the other hand, another combination (side–sealing on (5–AVA)x(MA)1–xPbI3, over– and side–sealing on FA0.9Cs0.1PbI3) resulted in decreased stability. For these degradation mechanisms, the FA–based perovskite, was decomposed by the condensation reaction between FA and carbon. For side–sealing, the space between the cell and the encapsulant was estimated to contain approximately 1,260,000 times more H2O than in over–sealing, which catalyzed the degradation of the perovskite crystal. Our results demonstrate that MA–based PSCs, which are generally considered to be thermally sensitive, can significantly extend their thermal stability after the proper encapsulation. Therefore, we emphasize that finding the appropriate combination of encapsulation technique and perovskite composition is quite important to achieve further device stability.

Figure 1
Ultrathin ALD SnOx Layer for the Interfacial Engineering of Co-Evaporated Sb2Se3 Solar Cells
Authors: Hoang Van-Quy , Lee Jaebaek , Jeon Dong-Hwan , Yang Kee-Jeong , Kang Jin-Kyu , Kadiri-English Bashiru , Sung Shi-Joon , Kim Dae-Hwan
Published: December 2024

Antimony selenide (Sb2Se3) is a promising photoactive material for low-cost, high-efficiency thin film solar cells due to its non-toxicity, earth-abundance, and unique quasi-1D crystal structure. In this study, we developed a simple co-evaporation technique for antimony chalcogenide on heated substrates at approximately 315 °C under vacuum conditions, which enabled the fabrication of highly pure Sb2Se3 light absorber layers. Additionally, we employed ultrathin SnOx layer prepared by atomic layer deposition (ALD) process as an interfacial engineering layer. The ultrathin ALD SnOx layer acts as a barrier, preventing direct contact between the Sb2Se3 absorber layer and the ammonium cation during the wet chemical deposition process of a CdS buffer layer. Our results demonstrate that the ultrathin ALD SnOx layer reduces recombination at the Sb2Se3/CdS interface. Through a comprehensive comparison involving solar cells with and without the ultrathin ALD SnOx layer, and with systematically varied Sb2Se3 thicknesses, we elucidate the underlying physical explanation of the interfacial engineering of Sb2Se3 solar cells by the ultrathin ALD SnOx layer. Owing to the interfacial engineering by the ultrathin ALD SnOx layer, the Sb2Se3 solar cells incorporating ALD SnOx achieved a power conversion efficiency (PCE) of 6.24%, which is considerably higher value compared with the reference Sb2Se3 solar cells without the ALD SnOx layer.

Acknowledgments

This research was financially supported by the Ministry of Trade, Industry and Energy (MOTIE) and Korea Institute for Advancement of Technology (KIAT) through the International Cooperative R&D program (Project No. P0024567) and by the DGIST R&D program of the Ministry of Science and ICT (24-ET-01).
Carbon Back Electrode Added SnO2 Nanoparticle for Scalable Multiporous-Layered-Electrode Perovskite Solar Cells
Authors: Shioki Takaya , Oishi Kouta , Matsumura Taiki , Tsuji Ryuki , Ito Seigo
Published: December 2024

Fully printable carbon-based multiporous-layered-electrode perovskite solar cells (MPLE-PSCs) has long-term stability, because the thick carbon layer (~15 μm) can be protected the perovskite light absorption crystals from ambient water and oxygen [1-5]. This allows MPLE-PSCs to be manufactured in air, and scale-up is possible when used in conjunction with printing technologies. However, the power conversion efficiency (PCE) is lower than that of general thin-film type perovskite solar cells. To solve this problem, we need to introduce high-quality perovskite light-absorbing crystals inside the porous layer by controlling the permeation and crystallization process of the perovskite precursor solution. In this study, it was found that by mixing SnO2 in the mesoporous carbon electrode, the SnO2 acts as an inorganic binder and helps the perovskite precursor solution to penetrate. MPLE-PSCs with a sub-module size of 15.17 cm2 active area were also fabricated using this SnO2-mixed carbon electrode.

In order to fabricate MPLE-PSCs, a hole blocking layer (compact-TiO2) layer was deposited on the FTO (fluorine-doped SnO2) glass substrate by the spray pyrolysis method. Then, electron transport layer (mesoporous TiO2), insulation layer (mesoporous ZrO2) and hole transport layer/back contact electrode (mesoporous carbon) were coated by screen printing method. Finally, the perovskite precursor solution ((HOOC(CH2)4NH3)0.05(CH3NH3)0.95PbI3, 1.2 mol/L in γ-butyrolactone) was dropped and annealed to complete the MPLE-PSCs [1].

Analysis of the pore size distribution of the carbon electrode, contact angle, and elemental distribution in the cross-section of the MPLE-PSCs showed that mixing SnO2 changed the morphology of the carbon electrode and allowed the perovskite precursor solution to penetrate throughout the mesoporous electrode. The PCE of MPLE-PSCs mixed with SnO2 was found to be 11.02 % at the optimum ratio (15 wt% SnO2 to carbon powder). Furthermore, the PCE of a sub-module fabricated with the same material achieved 9.03 %. This value represents a significant improvement by 22.9 % compared to the pristine-carbon case.

[1] A. Mei, et al., Science
345, 295 (2014).

[2] R. Tsuji, et al., Electrochemistry
88, 418 (2020).

[3] R. Tsuji, et al., Photonics
7, 133 (2020).

[4] D. Bogachuk, et al., Carbon
178, 10 (2021).

[5] E. Kobayashi, et al., Cell Rep. Phys. Sci.
2, 100648 (2021).
On Identifying Crossover Induced Self-Discharge of Non-Aqueous Redox-Flow Batteries and Ketazin Based Redox-Active Species
Authors: Fricke Sebastian , Krämer Susanna , Sowa Karin , Winter Martin , Gruenebaum Mariano
Published: December 2024

Redox flow batteries (RFB) are a promising technology for storing electrical energy in the grid because of their high scalability, design flexibility, long-term efficiency and durability. Hence, great efforts have been invested in this area of research. Especially in regards of organic redox-active species (RAS) a wide variety of different molecular design approaches have been examined. While many of these RAS are convincing due to their simple synthesis and cheap raw materials (cheap production) as well as high redox potentials (high cell voltage), high redox reversibility and low crossover tendency (high long-time stability), or high solubilities (high capacity), only a few can combine all these requirements for an optimal RAS.

In this work, we therefore present the functional group of ketazines (see Figure 1) as basis for organic RAS potentially exceeding previous organic RAS in RFB performance. With its simple two-step synthesis, easy variation of functionalization and low-cost raw material, this functional group offers not only high variability but also adaptability to specific NARFB (non- aqueous RFB) needs. This functional ketazine group is exemplary shown by the molecule AMAP here (see Figure 2).

In addition, we present a simple experimental procedure that can be used to analyse crossover rates of an RFB system (i.e. RFB cell structure, electrolyte composition and separator / membrane). To this end, we have developed a crossover mass transport concept that allows qualitative and quantitative crossover investigations. Using this experimental route, it is shown how different operating parameters within a specific RFB setup (e.g. RAS concentration, RAS structure, type of separator / membrane, ...) can influence the crossover behaviour of the RAS, and thus the resulting capacity loss. In this way, the comparability of different RFB systems can be improved and the best combination of RFB cell structure, electrolyte composition and separator/membrane for most efficient long-term charge-discharge cycling can be selected.

Figure 1
Natural Organic Pectin Polysaccharide Based Resistive Random Access Memory
Authors: Cheong Kuan Yew , Lee Hooi Ling , Zhao Feng
Published: December 2024

Nowadays, non-volatile memory technologies have been widely applied in different areas. Of these memory technologies, non-volatile resistive random access memory (ReRAM) is attractive because of its simple device architecture and fabrication process, high scalability and data density, good performances in terms of switching speed, high power efficiency and reasonably wide memory window. In order to address the issues of disposable and degradation of electronic waste by typical ReRAM with the active layer made of inorganic oxide materials and fossil-fuel based polymeric materials, a green and sustainable strategy has been adopted in producing ReRAM by using natural organic-based materials based on protein and carbohydrate, such as honey, fructose, aloe vera, etc. Among these materials, pectin-polysaccharide thin film has demonstrated promising resistive switching characteristics. The two ranges of pectin concentrations that have been investigated are ³5 mg/ml and £1.5 mg/ml, and it showed that pectin with concentration <1.5 mg/ml reveals a higher ON/OFF ratio. However, the resistive switching characteristics with pectin concentration between 1.5 mg/ml and 5 mg/ml have yet been explored and reported. In this work, pectin with concentrations of 1.5~5 mg/ml were prepared from pectin-polysaccharide solution into the active switching layer, and ReRAM devices with such pectin resistive switching layer were fabricated. The pectin-polysaccharide solution, pectin resistive film, and ReRAM devices were systematically investigated. Surface tension and contact angle of pectin-polysaccharide precursor solutions as a function of pectin concentration on the substrate were measured by a goniometer. Surface topography of solidified thin films was characterized by an atomic force microscope (AFM) and a field-emission scanning electron microscope (FE-SEM). Chemical functional groups of the pectin-polysaccharide precursor solutions and solidified thin films were examined by a Fourier transform infrared (FTIR) spectroscopy. The resistive switching behaviors were characterized and compared by electrical measurement. The results show that 4 mg/ml recorded the highest ON/OFF ratio compared to ever reported values, as well as desirable memory window, non-volatility in retention, and stability over 100 cycles. This study proves that pectin-polysaccharide is a promising green and sustainable bio-organic material for non-volatile ReRAM for electronic applications such as in emerging neuromorphic computing systems.
Precise Bottom-up Synthesis of Functional Nanowires and Nanosheets Based on 1D and Quasi-1D Van Der Waals Crystals
Authors: Arguilla Maxx
Published: December 2024

Anisotropy often leads to unexpected structures and properties in the solid state. In van der Waals (vdW) solids composed of 1D or quasi-1D (q-1D) building blocks, anisotropy in both intra- and inter-chain directions results in an abundance of crystalline packing motifs and drastically altered physical states. Among these, 1D/q-1D vdW solids that display topologically protected states, confined photonic modes, and direct band gap characteristics in few- to single-chains are highly sought after due to their tremendous potential as building blocks for next-generation quantum computing, spintronic, and telecommunication devices. Yet, access to such facet- and edge-specific physical states is still limited by the stochastic nature of micromechanical exfoliation. Here, we present two convergent efforts that address the growth of 1D and q-1D vdW crystals, which have closely related stoichiometric competing phases or exhibit rich polymorphism. First, I will describe the unique crystallization behavior of Bi4I4, a known topological insulator in bulk, in the presence of Au nanoparticle (NP) catalysts. Systematically varying Au NP diameters, Bi:I precursor ratios, and growth-deposition temperatures reveals that Au NPs generally act as nucleation sites for the vapor-solid (VS) growth of Bi4I4 nanowires. Strikingly, we discovered that post-synthesis analysis of 20 nm Au NPs, showing an equistochiometric 1:1 ratio of Bi to I within the Au NP, distinctly triggers the vapor-liquid-solid (VLS) growth of [001]-oriented quasi-2D nanosheets comprised of laterally-ordered [Bi4I4]n chains along the perpendicular [100] direction. Second, I will discuss how highly anisotropic and intrinsically strong covalent interactions along the long axis in 1D vdW crystals enable the uncatalyzed growth of record-long photonic nanowires (approximately 8 mm long with thicknesses ranging from 30 to 60 nm) via bottom-up vapor-phase routes. In both systems, we employ a series of structural and spectroscopic techniques to establish the structure, polytype, and physical properties of the well-defined nanowires and quasi-2D nanosheets that emerge from our synthetic routes.
Diameter and Morphology of Colloidal-Silica-Abrasives Depending on Surfactant Concentration with Amine-Functional Group
Authors: Park Jea-Gun , Jeon Min-Uk , Kim Pil-su , Kim Ju-Yeon , Jin Hyeong-Ju , Ahn Ho-Jun , Park Jin-Hyung
Published: December 2024

As the design rule of logic semiconductors has been scaled down to 5, 3, 2.1, 1.5, and 1.0 nm, the line width of Cu film used as interconnect lines in logic semiconductors has also been rapidly reduced to 36, 32, 24, 20, and 16 nm. The CMP (Chemical Mechanical Planarization) of these Cu lines is a crucial fabrication process, posing challenges in achieving E.O.E (Edge Over Erosion), as well as minimizing dishing and erosion during the CMP of Cu films. Specifically, the E.O.E in the CMP of Cu films is primarily influenced by the diameter and morphology of colloidal silica abrasives in the CMP slurry. In a conventional synthesis method synthesis of colloidal-silica-abrasives, the diameter of colloidal-silica-abrasives could be obtained by adjusting the precursor concentrations such as TEOS, alcohol, and alkali catalyst. It has been reported that the effect of precursor concentration and the presence of a carboxylic acid-functionalized surfactant, specifically ethylene-diamine-tetraacetic acid (EDTA), on the morphology of colloidal silica abrasives.

Therefore, in our study, we designed a novel synthesis method for colloidal silica abrasives by incorporating a charged functional group surfactant into the conventional synthesis process of colloidal silica abrasives. The effect of the surfactant having the positive charged amine functional group (i.e. Triethanolamine: Tri-ETA, Ethylenediamine: EDA, Diethylenetriamine: DETA, Triethylenetetramine: TETA) were estimated as function of the number of amine functional group in the surfactant, as shown in Fig. 1. When the number of positive charged amine functional groups increased 0 to 4, the diameter of colloidal-silica-abrasives increased from 67.2 to 143.86 nm and the solid loading of colloidal-silica-abrasives increased from 2.0 to 2.2 wt%. In addition, the synthesis with positive charged amine functional group was transformed from cocoon shape to spherical shape. We will present the changes in colloidal silica abrasive morphology as the concentration of amine functional groups, as well as the distinctions between amine and carboxyl funtuonal group. Moreover, we intend to provide a thorough investigation into the mechanisms underlying each synthesis.

Acknowledgement

This research was supported by the MOTIE(Ministry of Trade, Industry & Energy (1415180388) and KSRC(Korea Semiconductor Research Consortium) (20019474) support program for the development of the future semiconductor device, and by the Brain Korea 21 PLUS Program and the Samsung Electronics’ University R&D program.

Figure 1
Creation and Control of Lateral Electronic Junction in Ultrathin Semiconductor through the Interfacial Treatment Using Self-Assembled Monolayer
Authors: Han Junghyup , Kim Youn Sang
Published: December 2024

Interface engineering is essential to enhance the performance and stability of layered devices by resolving the interfacial issues, which dominantly affect the operation of the device. Unlike the interface, the adjoining bulk semiconductor is slightly affected by the interfacial treatment, and it is generally considered negligible in the classical semiconductor device theory. On the other hand, this interfacial effect is no longer trivial at the devices composing ultrathin layers, which are crucial for developing next-generation electronics with high integrity and low power consumption. Even though the semiconductors with tens of nanometers thickness, mainly used in current silicon-based industries, are significantly affected by the surrounding interfaces, however, this prominent interfacial influence is still underestimated. Herein, we show the substantial interfacial impact on the ultrathin semiconductor by the self-assembled monolayer (SAM) deposition, the p- to n-type inversion of the 50 nm silicon. The type and majority carrier density of the 50 nm silicon were determined by the interfacial dipole effect of SAMs according to their direction and strength, which was verified by Hall measurement and surface analysis such as UPS, XPS, and KPFM. As an interface engineering approach, the incorporation and control of SAMs show the potential as a simple alternative to the traditional impurity doping methods, which have difficulty in regulating the randomly distributed dopant in the case of the semiconductors with nanoscale thickness thereby causing unstable performance. Furthermore, we engineer the lateral electronic junction of the 50 nm silicon through the regioselective deposition of SAMs with opposite interfacial dipole, locally inducing p- and n-type silicon at each SAM-deposited region. Due to the presence of a lateral electronic junction, the 50 nm silicon exhibits the rectification behavior, which is reminiscent of a p-n diode. When we modulate the interfacial dipole of each SAMs through the ion pairing method using solutions of varying pH levels, the rectification ratio is sensitively changed. Therefore, the 50 nm silicon treated with the regioselective SAM deposition shows applicability as a pH sensing platform.
Moss-like Growth of Metal Electrodes: On the Role of Competing Faradaic Reactions and Fast Charging
Authors: Zheng Kent J.X.
Published: December 2024

Uncontrolled crystal growth during electroreduction of reactive metals in liquid electrolytes produces mossy metal deposits. Here we use electroanalytical Rotating-Disk Electrode (RDE) studies to elucidate the origin of moss-like growth of metals. We report that competing Faradaic reactions occurring on the electrode surface is the source of the phenomenon. A moss-like growth regime can be accessed by subtle shifts in electrolyte chemistry and deposition rate. Specifically, for Zn—a metal that conventionally is not known to form moss-like electrodeposits—obvious moss-like patterns emerge at low-current densities in strongly-alkaline electrolytes that undergo electroreduction to form an interphase. Conversely, under conditions where the rate of metal electroplating is large relative to that of other competing Faradaic reactions, it is possible to eliminate the moss-like growth. We further evaluate this principle in Li metal deposition and again find that the typical moss-like electrodeposit morphology of Li can be eliminated. As an empirical rule, an applied current density i that satisfies 10 is
< i < 0.8 ilim
could suppress instabilities giving rise to porous growth patterns. Our findings open up a new approach for achieving favorable metal deposition morphology and fast charging in next-generation batteries.
Influences of the Aqueous Electrolyte Composition and the Deposition Parameters on the Electrodeposition of Nickel-Rhenium Alloy
Authors: Omar Nurul Amanina Binti , Dombrowe Scott , Koester Frank , Lampke Thomas
Published: December 2024

Rhenium is used as an alloying element for many special materials in high-temperature applications, such as turbine blades, catalytic converter, and thermocouples. These applications require a high melting temperature of the materials, which can be achieved by a small amount of rhenium in the alloy. Rhenium has the second highest melting temperature after tungsten at 3186 °C [Naor et al., 2009]. Furthermore, at high temperatures, rhenium has a good resistance to creep and fatigue as well as to chemical reactions that occur in this temperature range. Due to its scarcity on earth and the resulting high prices, a broad application of rhenium using conventional manufacturing processes such as primary shaping like casting is not economical. [Naor et al., 2010]

A resource-conserving and economical process, on the other hand, is galvanic deposition, in which the required application-dependent properties can be produced in the form of a thin layer on inexpensive components. Rhenium can be electroplated from aqueous solutions, but only with poor current yields of around 10 %. With the aid of co-deposition of nickel, the current yield can be increased to approx. 90 % in laboratory scale. With the nickel-rhenium alloys depositions, rhenium deposition rates of up to 70 wt% could be realized. Furthermore, the layer properties can be influenced by the electrolyte composition and the process parameters.

The deposited Ni-Re layers were characterized using scanning electron microscopy-EDX, laser scanning microscopy and Vickers microhardness testing.
Kinetics and Stability of Sustainable Indium Alkaline Electrodeposition
Authors: Carrea Davide , Piccinni Marco , Friedman Gary , Colombara Diego
Published: December 2024

Indium is widely utilised for the fabrication of CuIn1-xGaxSe2 (CIGS) based solar cells1,2. Such devices are constituted by thin layers of various materials stacked on top of each other, one of which is the CuIn1-xGaxSe2 absorber layer itself. Cu-In-Ga alloys as absorber precursors can be obtained using cathodic electrodeposition of each separate elemental layer from three distinct galvanic baths containing Cu2+, In3+, and Ga3+ ions, respectively.

State-of-the-art indium galvanic baths display low faradaic efficiency. Being mostly acidic or neutral, these baths are affected by the hydrogen evolution reaction under highly cathodic potentials. The most known alternative to enhance faradaic efficiency is to employ non-aqueous media 3–5.

In this study, we present a sustainable alkaline galvanic bath yielding smooth In electrodeposits. Alkaline conditions naturally hinder hydrogen evolution, but favour strong precipitation of In2O3 and In(OH)3. Here, we solved this conundrum by identifying competitive organic compounds capable of complexing In3+, thus avoiding the formation of such precipitates. Moreover, we carried out potentiometric titration experiments to identify the stoichiometry of the coordination compounds.

This galvanic bath was formulated, characterized and stabilized for alkaline pH. The faradaic efficiency was assessed and the deposition kinetics explored using coulometric techniques on rotating disk electrodes (RDEs). We are currently investigating the deposition mechanism in detail and plan to leverage the acquired knowledge to further optimize the deposition process.

Acknowledgements

This work was supported in part by the Italian Ministry of Foreign Affairs and International Cooperation”, grant number US23GR17. REMAP6 has received funding from the European Commission PathFinder open programme under grant agreement No. 101046909. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Innovation Council and SME Executive Agency (EISMEA). Neither the European Union nor the granting authority can be held responsible for them.

References

J. Zhou and C. Li, in E3S Web of Conferences,, vol. 267, EDP Sciences (2021).

L. Thouin, S. Massaccesi, S. Sanchez, and J. Vedel, Formation of copper indium diselenide by electrodeposition, p. 81–88, (1994).

W. Monnens, C. Deferm, K. Binnemans, and J. Fransaer, Physical Chemistry Chemical Physics, 22, 24526–24534 (2020).

R. Piercy and N. A. Hampson, The electrochemistry of indium, p. 1–15, (1975).

S. Zein El Abedin et al., Electrochim Acta, 52, 2746–2754 (2007).

https://re-map.eu/
(Invited) Surface Morphology Evolution in the Presence of Halides
Authors: Huo Chanyuan , Mubshrah Ayesha , Schwarzacher Walther
Published: December 2024

The presence of halides in an electrolyte can strongly influence the evolution of the surface morphology of an electrodeposited polycrystalline metal film, with implications for its microstructure and applications. Surface coarsening can take place with or without an increase in surface slope. We show that the addition of chloride anions leads to significant changes in the surface slope evolution for Ni electrodeposition. We shall also present new data that show the effect of bromide adsorption on the dynamics of Au atoms in nano-contacts formed by the STM break junction technique.
Mitigating Anodic Reactions in Water-in-Salt Electrolytes for Refractory Metal Electrodeposition
Authors: McBride Michael , Rutledge Amanda , Hooks Daniel E
Published: December 2024

The use of water-in-salt electrolytes has been a transformational advancement in electrochemistry. Water-in-salt electrolytes rely on a super high concentration of salts in aqueous electrolytes to lower the activity of water. The water is occupied in the solvation of the salts, leaving minimal ‘free water’ in the system. In the context of electrodeposition, this results in a widened cathodic window as the limited quantity of protons suppresses the hydrogen evolution reaction (HER).

Seldom discussed is the impact on anodic reactions that are also limited by the transport of water for the oxygen evolution reaction (OER). Lithium chloride (LiCl) has been used as a cost effective and readily available support salt in water-in-salt electrolytes. However, in this system OER competes with chlorine evolution. At low pH chlorine evolution is more thermodynamically and kinetically favorable. This reaction depletes the system of chlorine atoms required to solvate excess water and saturates the electrolyte with dissolved chlorine. As a result, the electrolyte has a limited lifetime.

One solution to this problem is the use of proton exchange membranes to separate the anode from the cathode. The use of these membranes will be discussed focused on our interest in rhenium (Re) electrodeposition. Rhenium has traditionally been difficult to deposit by electrolysis from aqueous solutions due to the over potential for hydrogen evolution and complex electrochemical reactions. Further, many intermediate rhenium oxides catalyze HER, so maintaining a stable water-in-salt electrolyte is crucial.

Herein, we present systematic studies investigating various proton exchange membranes in an H-cell confirmation on the electrodeposition of rhenium. Perfluorosulfonic acid and hydrocarbon polymer backbones are explored, both with sulfonic acid functional groups. As these membranes are semipermeable, membrane thickness is also explored. Both volume changes in the two H-cell components and pH are monitored as a function of time. The impact on the morphology and electrodeposition kinetics of rhenium will be presented as a function of membrane properties.
Anomalous Electrodeposition of Palladium – Antimony Alloys
Authors: Freydina Evgeniya , Monroe Jeffrey C. , Hilty Robert D.
Published: December 2024

Electrodeposition of Pd-Sb alloy was studied in tartrate – ammoniacal electrolytes. Unlike any other known binary plating system, the resulting alloy was typically obtained with anomalously constant composition of about 30 wt.% antimony in a large process window. Factors like concentrations of Pd and Sb in solution, current density, temperature and agitation only slightly affected the Sb content in the deposit.

The alloy exhibits several practical properties. As plated, it has a nanocrystalline structure and a moderate compressive stress of about 13 ksi (90 MPa). It is harder than pure palladium with typical Vickers microhardness of 550-650 HV10 and has good wear durability and corrosion resistance.

The plating process produces unexpectedly uniform composition and properties on the substrates with the most intricate shapes. Meanwhile, plating thickness tracks with local current density fluctuations we expect on a complex shaped part.

Cyclic voltammetry provides some insight into the unusual co-deposition of palladium and antimony. Additional data on the structure of the electrolyte and the deposit are presented.

Figure 1. A part coated with Pd-Sb alloy. The Sb content (wt.%) is uniform around the surface of the part.

Figure 1
Adsorption of Organic Molecules at Solid-Electrolyte Interface – the Effect of the Electrolyte and Electrode Structure
Authors: Pikma Piret , Ers Heigo , Siinor Liis
Published: December 2024

Understanding processes at the molecular level at the solid-liquid interface is essential to improving and developing novel technologies in electrochemistry, molecular electronics, catalysis, corrosion inhibition, electrodeposition of metals, formation of composite layers, and energy storage devices. Self-assembled monolayers (SAMs) play a significant role in many of those applications and their improvements [1-2]. At the same time, the characteristics of SAMs depend on many aspects, like the characteristics of individual molecules forming the monolayer, the interactions between these molecules, SAM interactions with the electrolyte, the crystalline surface of the substrate, etc.

The adsorption of bipyridines resulting in the formation of various nanostructures at the electrode surface has been studied in both aqueous electrolytes [2-5] and, more recently, in IL medium [6-8]. The adsorption of bipyridines is of interest as it offers insight into the interactions which drive the formation of self-assembled monolayers. This is due to aromatic nitrogen-containing heterocycles, which facilitate the possibility of interacting with the surface or other molecules through nitrogen lone electron pair, π-π stacking or hydrogen bonds.

To this day, the universal understanding that the adsorption of organic molecules results in the formation of an ordered monolayer is based on the phenomenon observed in mainly aqueous solutions. However, the conception might not be straightforwardly transferrable to the organic additive + ionic liquid | electrode interface. For example, the existence of an interfacial multilayer structure of pure IL ions in contrast with an aqueous electrolyte has been previously shown in both experimental and computational studies. Furthermore, it has been shown that in ILs, if the ions form rigid layers on the electrode, it is necessary to apply an overpotential for interfacial restructuring.

This work compares the adsorption of 4,4′-BP and 2,2′-BP at the interfaces between various metal single crystal electrodes (Sb, Bi, Au, Cd) and aqueous or ionic liquid electrolytes. The adsorption process has been studied by applying scanning tunnelling microscopy, electrochemical impedance spectroscopy and cyclic voltammetry methods. Based on the comparison, similarities and differences between aqueous and ionic liquid as electrolytes will be pointed out. Additionally, the influence of the physical and chemical properties of the various metal single crystal electrodes will be discussed.

[1] D. R. MacFarlane, et al., Energy Environ. Sci. 7, 232–250 (2014)

[2] N.V. Plechkova et al., Chem. Soc. Rev. 37, 123–150 (2008)

[3] Pikma et al., Electrochem. Commun. 2015, 61 (Supplement C), 61–65.

[4] H. Ers et al., Electrochim. Acta 2022, 421, 140468.

[5] H. Ers et al., J. Electroanal. Chem. 2021, 903, 115826.

[6] L. Siinor et al., Electrochem. Commun. 2013, 35, 5–7.

[7] L. Siinor et al., J. Electroanal. Chem. 2014, 719, 133–137.
Maximizing CdTe Nanowire Potential: Rapid Electrodeposition for High-Performance Photoanodes
Authors: Adesanoye Samuel , Cheng Wei , Jawahar Hussaini Syed Mubeen
Published: December 2024

Vertically aligned CdTe nanowire arrays mitigate performance losses from crystallographic defects through efficient strain relaxation and enhance light trapping, absorption, and charge extraction due to their radial geometry and architecture. This transformative nanostructured solution could address the long-standing defect and fault tolerance issues hindering the performance of polycrystalline CdTe thin-film solar cells. Crucially, our breakthrough modified electrodeposition approach enables unprecedently rapid growth of these nanowire arrays at astonishing rates up to 500 nm/min - a game-changing achievement for industrial-scale manufacturing and economic viability. Executed at room temperature and followed by a simple, low-cost air annealing step, this technique significantly reduces fabrication costs and complexity compared to vapor-based methods. The resulting nanowire arrays exhibit exceptional structural and optoelectronic properties: highly uniform 70 nm average diameter, lengths up to an impressive 1 μm, an ideal direct 1.5 eV bandgap, and outstanding 10 ns minority carrier lifetime. Furthermore, integrating a wider 1.65 eV bandgap CdSeTe ternary window layer synergistically leverages the favorable conduction band alignment to unlock impressive photovoltaic performance with 16 mA/cm² short-circuit current density and 0.6 V open-circuit voltage. While further optimizations are ongoing to boost performance even higher, our innovative approach already overcomes longstanding barriers by combining the inherent advantages of nanostructured geometries with optimized junction designs, enabling scalable and cost-effective manufacturing of high-efficiency CdTe nanowire-based photovoltaics with unparalleled conversion efficiencies.
Advancements in Analyzing Organic Additives in Electroplating Baths: A Focus on Electrochemical Impedance Spectroscopy (EIS) Coupled with Distribution of Relaxation Times (DRT)
Authors: Giurlani Walter , Verrucchi Margherita , Bonechi Marco , Zangari Giovanni , Innocenti Massimo
Published: December 2024

Organic additives play a crucial role in upholding the quality of metallic coatings within commercial electroplating baths. However, their effectiveness diminishes over time due to degradation and drag-out. Continuous monitoring and precise dosing are imperative to uphold optimal concentration levels, preserving both technical integrity and aesthetic appeal. Traditional chromatographic techniques are impractical for routine industrial analysis due to the complex formulation and synergistic effects of various additives. Electrochemical methods, such as the Hull cell test and Cyclic Voltammetric Stripping (CVS) measurements, are commonly employed to adjust additive concentrations based on their impact on the electrodeposition process. Although widely utilized, the Hull cell test relies on trial and error and operator experience, providing only qualitative assessments. CVS, which measures changes in the rate of copper deposition to reflect additive concentration, may not be universally suitable for all electroplating baths due to their varying complexities.

Prior Electrochemical Impedance Spectroscopy (EIS) investigations on copper plating baths have qualitatively linked impedance changes with aging [1]. Our objective was to quantify additives using EIS. To achieve this, experimental data were analyzed in terms of resistive and capacitive components to calculate the distribution of relaxation times (DRT) via Lasso regression [2]. The resulting data were subjected to multivariate analysis to address this challenge.

The promising outcomes [3] render this method highly appealing in both industrial and academic contexts. Its application in the galvanic field is particularly advantageous for gaining insights into the function of individual additives, their interactions, and the aging process of plating baths.

Project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.3 - Call for tender No. 341 of 15 March 2023 of Italian Ministry of University and Research (MUR) funded by the European Union - NextGenerationEU - Project code PE_00000004, CUP B83C22004890007, Project title "3A-ITALY - Made-in-Italy circolare e sostenibile".

References

[1] C. Gabrielli et al., J. Appl. Electrochem. 2008, 38, 457–468.

[2] A. Piccioni et al., J. Phys. Chem. C 2023, 127, 7957–7964.

[3] M. Verrucchi et al., J. Electroanal. Chem. 2024, 954, 118045.
Electrochemically Deposited Nanoarchitectured Nanoporous Metal Film Using Block Copolymer Micelle for Ultra-Sensitive SERS Platform
Authors: Jisoo Park , Jeonghun Kim
Published: December 2024

Utilizing surface-enhanced Raman scattering (SERS) substrates with plasmonic metals is a rapid, convenient, and powerful spectroscopic technique for molecule detection. The performance of SERS, including the limit of detection (LOD) and enhancement factor (EF), relies on the SERS substrate. These substrates contain plasmonic nanostructures, and the formation of nanogaps between them is one of the crucial factors. Therefore, the development of nanomaterials and nanostructures plays a pivotal role in creating high-performance SERS substrates. Despite numerous studies, achieving rich nanogap formation and establishing reliable processes remain challenging tasks. Firstly, we introduce a novel nanoarchitecture technique utilizing nanoporous metal films and nanoparticles to create abundant nanogaps. We fabricated a new type of SERS substrate with plasmonic nanoporous Au films using a soft-templating method combined with electrochemical deposition. Through precise surface modification and control of surface charge, we achieved well-defined nanogaps. Additionally, we present a new nanoarchitecture technique for forming hotspots by adjusting the gaps between nanoporous plasmonic Au pattern films. By adjusting the deposition voltage and time, we controlled the gaps between the patterns. The nanopatterns and nanoporous structures exhibit strong light trapping ability, owing to multiple reflections of light in the pore, and they possess a larger specific surface area, which enhances the enrichment of target molecules, leading to the formation of more "hot spots" and the enhancement of LSPR effect. Moreover, the multiple electric field couplings of the nanopatterns and nanoporous structures further enhance the local electromagnetic field. In conclusion, 3D SERS sensors hold great potential for revolutionizing various fields such as environmental monitoring, medical diagnostics, and chemical analysis. These products feature ultra-high sensitivity, high spatial resolution, and customizable design, making them indispensable tools for detecting and analyzing molecules at low concentrations. The advancements in substrate fabrication bring us one step closer to maximizing their potential, and continuous research and development will undoubtedly transform approaches to molecular analysis. This presentation emphasizes the importance of utilizing reliable nanomaterials and nanoarchitecture techniques for nanogap formation.

Figure 1
(Invited) Overview of Cathode-Electrolyte Interphase (CEI) Consortium
Authors: Xiao Jie
Published: December 2024

This talk will highlight the progress of CEI Consortium focusing on understanding and addressing the key challenges of CEI at high voltages for next-generation Li-ion batteries. The three thrusts on model cathode, electrolyte and characterization/modeling will be discussed regarding the methodology used to revisit fundamental challenges of CEI at industry relevant scales.