Article
Chemistry, Inorganic & Nuclear
Kota Matsumoto, Hideyuki Kawasoko, Noriaki Kimura, Tomoteru Fukumura
Summary: In this study, oxygen intercalation and hole doping were achieved by co-sintering alkaline earth metal oxides with La2O2Bi, leading to an expansion of the c-axis length and improved electrical conduction. The hole mobility in La2O2Bi was significantly enhanced, reaching up to 150 cm(2) V-1 s(-1), almost double the value reported in previous studies.
DALTON TRANSACTIONS
(2021)
Article
Physics, Multidisciplinary
I. C. Lin, M. H. Lee, P. C. Wu, S. C. Lin, J. W. Chen, C-C Li, G. Y. Guo, Y-H Chu, R. Sankar, M-W Chu
Summary: Thin oxide films offer vast opportunities for modern electronics, and this study demonstrates the twisting of metallic phases into distinct charge-lattice entangled states by epitaxial strains. The research reveals lattice instabilities and localized hole doping in LaNiO3, PrNiO3, and NdNiO3 films on SrTiO3. These findings indicate the existence of hidden orders in versatile oxide heterostructures with unexpected properties.
NEW JOURNAL OF PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
A. Singh, H. Y. Huang, Christopher Lane, J. H. Li, J. Okamoto, S. Komiya, Robert S. Markiewicz, Arun Bansil, T. K. Lee, A. Fujimori, C. T. Chen, D. J. Huang
Summary: The layered crystal structures of cuprates exhibit unique charge excitations different from three-dimensional metals. Acoustic plasmons have been observed in electron-doped cuprates, but their existence in hole-doped cuprates is still debated. In this study, resonant inelastic x-ray scattering measurements and calculations were conducted to investigate the charge excitations of hole-doped cuprate La2−xSrxCuO4. The results provide evidence for the acoustic plasmons of Zhang-Rice singlet and suggest that the metallic behavior is attributed to the movement of Zhang-Rice singlet rather than simple hopping of oxygen holes.
Article
Chemistry, Multidisciplinary
Matias Berdakin, German Soldano, Franco P. Bonafe, Varlamova Liubov, Balint Aradi, Thomas Frauenheim, Cristian G. Sanchez
Summary: The injection of plasmon-induced hot carriers in the Au-TiO2 system has been studied and it is found that pure electronic features contribute significantly to the stability of electron-hole separation, leading to photocatalytic dissociation.
Article
Engineering, Electrical & Electronic
V. Vasanthi, N. Sivanantham, L. Saathvika, N. Gopalakrishnan
Summary: As LEDs dominate the current display industry, it is crucial to focus on the research and development of device structure, fabrication methods, and performance of LEDs. In organic LEDs (OLEDs), quantum dot LEDs (QLEDs), and pervoskite LEDs (PeLEDs), charge transport layers (CTLs) play a vital role in improving device structure and performance. Factors such as chemical stability, thermal stability, charge carrier density, charge carrier mobility, molecular/atomic energy levels, and processability greatly impact the efficiency and performance of LED devices. Metal oxides have shown promise as reliable materials for CTLs, surpassing conventional organic charge transport materials. This paper discusses the application of metal oxides as hole/electron transport layers in different LED architectures and their performance.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Chemistry, Multidisciplinary
Rui Zhang, Xinlei Gu, Kan Zhang, Xinxin Gao, Chang Liu, Changfeng Chen
Summary: A distinct VEC-CEC descriptor is developed to sort the mechanical properties of diverse transition-metal compounds with higher accuracy and versatility compared to many other commonly used descriptors. By considering both valence electron concentration (VEC) and core electron count (CEC), this descriptor captures the unregulated property variations and enhances the rational design and optimization of these compounds with tailored performance benchmarks.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Felipe Andres Garces-Pineda, Huu Chuong Nguyen, Marta Blasco-Ahicart, Miguel Garcia-Tecedor, Mabel de Fez Febre, Peng-Yi Tang, Jordi Arbiol, Sixto Gimenez, Jose Ramon Galan-Mascaros, Nuria Lopez
Summary: The study investigates Fe-Ni-Zn spinel oxides as a platform for understanding the key contributions to oxygen evolution reaction (OER) electrocatalysis, finding that the presence of Zn in the spinel structure and the density of specific equimolar stoichiometric sites play crucial roles in maximizing OER performance. The work demonstrates cooperative electronic effects on surface active sites as essential for designing optimal OER electrocatalysts.
Article
Chemistry, Physical
Siddharth Singh, Diksha Mittal, Vinithra Gurunarayanan, Ankita Sahu, Ramesh Ramapanicker, Vishal Govind Rao
Summary: Efficient charge extraction in lead halide perovskite nanocrystals is investigated using ferrocene-based molecules with different functional groups. It is found that different functional groups have different effects on the photoluminescence and lifetime of the perovskite nanocrystals. In particular, the -NMe2 functional group can passivate the defects on the perovskite surface, improving its photocatalytic performance.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
C. Gousiadou, R. L. Marchese Robinson, M. Kotzabasaki, P. Doganis, T. A. Wilkins, X. Jia, H. Sarimveis, S. L. Harper
Summary: This study utilizes machine learning techniques to create nano-QSAR tools for predicting nanomaterial toxicity, finding that core composition, concentration, and surface properties are key factors influencing toxicity.
Article
Chemistry, Physical
Qi Shen, Xiaojuan Sun, Song Chen
Summary: High work-function metal oxides are commonly used to enhance hole injection into organic semiconductors. However, the current understanding of the electrostatic mechanism needs to be more consistent with the electronic properties of materials. This study investigates the electrostatic profile of high work-function oxides by considering their dielectricity and energetic disorder. It is found that the significant vacuum-level change at the electrode-oxide interface in MoO3 is mainly due to electrode doping, rather than the conventionally assumed interface dipole. Moreover, electrode doping is sufficient to explain the Fermi-level shift, indicating that the n-type property of MoO3 is not necessarily due to intrinsic donors. This conclusion also applies to other n-type oxides with reduced work functions, such as WO(3), V2O5, and p-type NiO. Additionally, the dielectricity of the oxide reduces the surface p-doping of the deposited organic layer, and increasing the oxide's metallicity and energetic disorder facilitates hole injection.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Nanoscience & Nanotechnology
P. Puphal, V. Sundaramurthy, V. Zimmermann, K. Kuester, U. Starke, M. Isobe, B. Keimer, M. Hepting
Summary: The discovery of superconductivity in hole-doped infinite-layer nickelates has spurred interest in synthesizing novel nickelate phases, mostly examined in thin film samples. In this study, we report the growth of various perovskite and perovskite-derived rare-earth nickelate single-crystals using high-pressure optical floating zone (OFZ) method, and investigate the effects of different types of doping. Our results show phase separations during growth process when a substitution level of 8% is exceeded for hole-doping with Ca and Sr, and similar trends for electron-doping with Ce and Zr. By employing lower doping levels, we are able to grow large crystals in the perovskite phase, which exhibit distinct electronic and magnetic properties compared to undoped parent compounds.
Article
Chemistry, Physical
Deep Mukherjee, Upendra Harbola
Summary: Ionization time delay measures the time it takes for an electron to move from a bound molecular state to a free state, while a similar timescale is associated with hole dynamics in response to ionization. We demonstrate that ionization time delay and hole dynamics time delay are interdependent, both arising from complex amplitudes of multiple ionization pathways resulting in different cationic states. Sudden ionization eliminates the time delay for hole dynamics. We calculate the ionization and hole dynamics time delays in a glycine molecule and illustrate how photoionization influences hole dynamics, leading to a nonzero hole-density flux immediately after ionization.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Inorganic & Nuclear
Xiang Li, Qiulin Li, Wenjing Shang, Yongbing Lou, Jinxi Chen
Summary: Solar-driven water splitting is an advanced method to store abundant and intermittent solar energy and produce clean hydrogen. Constructing well-designed photocatalysts is a promising approach for clean hydrogen energy development. In this study, flower spherical UiO-66-(SCH3)(2)/ZnIn2S4 (UiOSC/ZIS) photocatalysts were synthesized and showed high hydrogen production activity in light-driven water splitting.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Physical
A. Ya Freidzon, A. A. Bagaturyants, Ya Burdakov, V. R. Nikitenko, V. A. Postnikov
Summary: A computational procedure for predicting charge hopping rate in organic semiconductor crystals is proposed and verified using a p-quaterphenyl molecular crystal. The study found that different arrangements of monomers in the crystal structure affect charge hopping parameters, resulting in different hole mobilities in different directions.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Shai R. Vardeny, Alan Phillips, Kira A. Thurman, Z. Valy Vardeny, Jeffrey L. Blackburn
Summary: This article investigates the mid-infrared charge signatures of heavily p-type doped polymer-wrapped single-walled carbon nanotubes (s-SWCNTs). The study finds that hole charge carriers induce strong Fano anti-resonances in mid-infrared transmission spectra and analyzes the relative intensities, energies, and sources of all observed anti-resonances.
Article
Chemistry, Physical
Young Won Woo, Zhenzhu Li, Young-Kwang Jung, Ji-Sang Park, Aron Walsh
Summary: This study investigates the competition between corner-, edge-, and face-sharing octahedral networks and its effect on phase inhomogeneity in metal halide perovskite thin-films. The authors use first-principles materials modeling to probe the distribution and transport of charged iodine vacancies in the junction between cubic and hexagonal polytypes of CsPbI3. The results show that defects have lower formation energy and higher mobility in the face-sharing regions, which may influence carrier dynamics in perovskite-based solar cells and electrical devices.
ACS ENERGY LETTERS
(2023)
Article
Chemistry, Physical
Yong-Seok Choi, Sara I. R. Costa, Nuria Tapia-Ruiz, David O. Scanlon
Summary: The development of high-power anode materials for Na-ion batteries is hindered by the low electrical conductivity and poor structural stability of Na2Ti3O7. Approaches such as aliovalent doping and hydrogenation/hydrothermal treatments have been proposed to overcome these drawbacks, but the intrinsic defect chemistry of Na2Ti3O7 is still not well understood. This study employs hybrid density functional theory calculations to investigate the native defect chemistry of Na2Ti3O7 and provides insights on the interplay between defects, structural phase transitions, and electrical conductivity.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Kazuki Morita, Matthias J. Golomb, Miguel Rivera, Aron Walsh
Summary: Polarons are localized excess charge in materials, especially transition metal oxides, which are of fundamental interest for photochemical and electrochemical reactions. This study focuses on the model system rutile TiO2 and investigates the effect of impurity doping on polaron formation. Additionally, two metal-organic frameworks (MOFs), MIL-125 and ACM-1, are compared to TiO2, demonstrating the influence of ligands and connectivity on polaron mobility.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Kasper Tolborg, Aron Walsh
Summary: The researchers investigated the tetragonal-to-cubic phase transition of ZrO2 at high temperatures using anharmonic lattice dynamics and molecular dynamics simulations. They found that the stability of cubic zirconia cannot be solely explained by anharmonic stabilization, but may also involve spontaneous defect formation and entropic stabilization, which is responsible for its superionic conductivity at elevated temperatures.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Chemistry, Multidisciplinary
Adair Nicolson, Joachim Breternitz, Sean R. Kavanagh, Yvonne Tomm, Kazuki Morita, Alexander G. Squires, Michael Tovar, Aron Walsh, Susan Schorr, David O. Scanlon
Summary: Researchers predict and confirm a disordered room-temperature structure of the mixed-anion crystal Sn2SbS2I3 using a first-principles cluster expansion approach and single-crystal X-ray diffraction. The disorder reduces the bandgap from 1.8 eV at low temperature to 1.5 eV at a specific annealing temperature. Tailoring the cation disorder allows for targeted bandgap engineering, making this crystal useful for optoelectronic applications, including graded solar cells. Further investigation into the material properties associated with defect and disorder tolerance is encouraged.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Irea Mosquera-Lois, Sean R. Kavanagh, Aron Walsh, David O. Scanlon
Summary: Point defects are common features in crystals, and their identification is usually achieved through a combination of experimental measurements and theoretical models. However, the standard modelling approach often fails to consider energy-lowering reconstructions from the ideal crystallographic environment, resulting in missed ground state atomic configurations and compromised accuracy of calculated properties. To overcome this issue, we propose an approach that utilizes targeted bond distortions and rattling to navigate the defect configurational landscape. Applying this method to eight different materials reveals symmetry breaking in each host crystal that conventional local minimisation techniques fail to capture. The point defect distortions are classified based on their associated physico-chemical factors, and their impact on derived properties such as formation energies, concentrations, and charge transition levels is demonstrated. This work represents a significant advancement towards quantitative modelling of imperfect solids.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Danny Broberg, Kyle Bystrom, Shivani Srivastava, Diana Dahliah, Benjamin A. D. Williamson, Leigh Weston, David O. Scanlon, Gian-Marco Rignanese, Shyam Dwaraknath, Joel Varley, Kristin A. Persson, Mark Asta, Geoffroy Hautier
Summary: Calculations of point defect energetics with DFT methods provide valuable insight into various properties. This work compares automated, semi-local point defect calculations with a-posteriori corrections to gold standard hybrid calculations. The study evaluates qualitative and quantitative differences in defect information and highlights the potential and limits of high-throughput calculations based on semi-local DFT methods.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Energy & Fuels
Jiayi Cen, Bonan Zhu, David O. Scanlon
Summary: In this study, ab initio random structure searching (AIRSS) was used to accelerate materials discovery of the Li-Ni-O phase space. The study discovered structures (such as LiNiO2) displaying dynamic Jahn-Teller effects and a thermodynamically stable Li2Ni2O3 phase. Additionally, many dynamically stable structures close to the convex hull were encountered, confirming the presence of metastable Li-Ni-O phases and revealing their structures and properties. This work will facilitate the identification of Li-Ni-O phases in future experiments and address the challenges in synthesizing these phases.
JOURNAL OF PHYSICS-ENERGY
(2023)
Article
Chemistry, Physical
Gabriel Krenzer, Johan Klarbring, Kasper Tolborg, Hugo Rossignol, Andrew R. McCluskey, Benjamin J. Morgan, Aron Walsh
Summary: In this study, molecular dynamics simulations were used to investigate the type-II superionic phase transition in α-Li3N. The findings suggest that the superionic transition may be driven by a decrease in defect formation energetics rather than changes in Li transport mechanism. This insight may have implications for other type-II superionic materials.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Kanta Ogawa, Hajime Suzuki, Aron Walsh, Ryu Abe
Summary: Three novel bismuth-based layered oxyiodides with increased water oxidation activity under visible light were reported. The electronic structure of these compounds is controlled by the Bi-Bi interaction, resulting in enhanced photoabsorption and reduced band gap. This research not only provided new photocatalysts for water splitting, but also offered a pathway to control the optoelectronic properties of lone-pair semiconductors.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Bastien F. Grosso, Daniel W. Davies, Bonan Zhu, Aron Walsh, David O. Scanlon
Summary: Building on previous research on metal oxide and metal halide perovskites, this study focuses on the largely unexplored realm of metal nitride perovskites. Through extensive computational screening, the researchers predict 12 stable nitride perovskite materials with significant electric polarization and low predicted switching electric field, making them attractive for ferroelectric memory devices. Promising compositions include YMoN3, YWN3, ZrTaN3, and LaMoN3.
Article
Chemistry, Physical
Katarina Brlec, Christopher N. Savory, David O. Scanlon
Summary: Utilising photocatalytic water splitting is crucial for producing green hydrogen and reducing the carbon footprint of this important chemical feedstock. This study employs density functional theory (DFT) to gain insights into the photocatalytic performance of a promising photocatalyst, Y2Ti2O5S2, from first principles. The study evaluates eleven non-polar clean surfaces at the generalised gradient approximation level and further considers the (001), (101), and (211) surfaces at the hybrid-DFT level to determine their band alignments. The study also establishes relevant optoelectronic bulk properties using a combination of hybrid-DFT and many-body perturbation theory.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Adair Nicolson, Sean R. Kavanagh, Christopher N. Savory, Graeme W. Watson, David O. Scanlon
Summary: Copper-chalcogenides are prospective materials for thin film solar cells due to their desirable electronic properties and defect tolerance. In this study, we investigate the optoelectronic properties of Cu2SiSe3 and find that it exhibits a direct bandgap of 1.52 eV and a maximum efficiency of 30% for a 1.5 μm-thick film at the radiative limit. The formation energies of intrinsic defects are calculated, revealing that the dominant defect species is the p-type copper vacancy, which forms a perturbed host state. Overall, we propose further investigation of Cu2SiSe3 as a potential defect-tolerant photovoltaic absorber.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Ju Huang, Seung-Jae Shin, Kasper Tolborg, Alex Ganose, Gabriel Krenzer, Aron Walsh
Summary: Through molecular dynamics simulations, it is found that the local structures of layered covalent organic frameworks (COFs) deviate from the average crystal structures determined by X-ray diffraction experiments. The simulations using a machine learning force field show that the stacking behavior of COFs is more complex than previously understood.
MATERIALS HORIZONS
(2023)
Article
Materials Science, Multidisciplinary
Xinwei Wang, Sean R. Kavanagh, David O. Scanlon, Aron Walsh
Summary: The study reveals the phenomenon of negative-U behavior in Sb2Se3, where a defect traps a second charge carrier more strongly. Utilizing a global structure searching strategy, the researchers found large atomic reconfigurations that facilitate charge redistribution. Thermodynamic analysis shows a four-electron negative-U transition for both VSe and VSb, indicating that all intrinsic point defects in Sb2Se3 exhibit amphoteric behavior.
