Work Function Research Articles

Multi-head spatial atomic layer deposition: a robust approach for precise doping and nanolaminate fabrication in open-air environments.

Open-air manufacture of functional nanolaminates demands rapid and scalable methods that maintain nanoscale precision across individual layers. Conventional spatial atomic layer deposition (SALD) employs a single deposition head, and the concurrent exposure to mutually reactive precursors does not provide precise layer thickness accuracy nor sharp interfaces. This work addresses these challenges with an innovative multi-head SALD design. In this study, we introduced a novel multi-head SALD system comprising a uniform head for depositing 5 nm zinc oxide (ZnO) sublayers, while a combinatorial high-throughput head delivered wedge-like thickness gradient in aluminum oxide (Al2O3) sublayers, increasing gradually from 0 to approximately 6 nm along the substrate. Eight ZnO/Al2O3 bilayers (320 ALD cycles per material) were completed in open air at 200 °C. Transmission electron microscopy recorded highly sharp and reproducible layer-to-layer structures with thickness deviations of 0.3 nm; X-ray photoelectron spectroscopy verified the absence of undesirable aluminum contamination in the reference ZnO regions. With increasing Al2O3 thickness, surface roughness was reduced from 0.58 to 0.33 nm, ZnO (002) reflections broadened as crystallite size was confined, and Kelvin probe measurements showed a shift in work function values from 4.75 to 4.35 eV with Al2O3 passivation. This study demonstrates that the multi-head SALD method offers a robust platform for achieving precise multilayer control in open-air conditions, thereby paving the way for further innovations in materials research through optimized experimental conditions and combinatorial approaches.

Covalently Doped and Highly Oriented Covalent Organic Framework Thin Films.

Strict control of both crystallographic orientation and band structure is crucial in realizing future high performing semiconducting microelectronic devices based on 2D covalent organic frameworks (COFs). Due to the insoluble nature from extensive aromaticity, processing of these materials into well-ordered, highly crystalline thin films presents a great challenge. In this work, a strategy to enable controlled covalent doping of imine COF thin films with thiophene linkers is presented. By incorporating different aldehyde ratios of terephthalaldehyde (PDA) and 2,5-thiophenedicarboxaldehyde (TDA) with 1,3,5-tris(4-aminophenyl)benzene (TAPB) in a liquid-solid synthesis approach, a series of highly crystalline and uniformly oriented TAPB-PDA-TDA COF thin films with varying percentages of TDA linkers incorporated into the framework were obtained. In this case, incorporation of thiophene linkers up to 20% resulted in minimal disruption of the long-range crystallographic ordering. Moreover, a small amount of thiophene molecules covalently doped into the highly ordered structure results in a small reduction in the band gap and a corresponding increase in the work function and decrease in the valence band maximum, effectively behaving like a p-type dopant in conventional semiconductors. The covalently doped thiophene unit is shown to increase the π-conjugation through enhanced crystallinity in the framework, improving the electron delocalization in the structure.

Tailoring optoelectronic properties of TMDs through atomic-scale solid-liquid interface engineering.

Transition metal dichalcogenides (TMDs) hold immense promise in photoelectrochemical applications, yet the atomic-scale electron transfer dynamics at their aqueous interfaces remain elusive. Here, we systematically investigate the underlying physical principles for MoS₂, MoSe₂, and MoTe₂ contact with water using first-principles calculations. Our calculations reveal that interfacial charge transfer occurs exclusively between surface atoms and adjacent water molecules, with the directionality governed by the relative work functions and the external pressure from water. This interfacial charge redistribution triggers band gap narrowing through conduction band downshift, directly modulating the optical responses. In-depth evaluation of joint density of states (JDOS) and critical points reveal that aqueous contact induces new characteristic peaks, broadening the high-intensity region. These findings advance the fundamental understanding of solid-liquid interfacial electrochemistry and establish a theoretical framework for semiconductor-based interfacial electron transfer. Moreover, our work highlights the feasibility of tailoring optical properties at the atomic scale through precise solid-liquid interface engineering, offering transformative insights for next-generation optoelectronic devices.

Constructing Built‐In Electric Field in Na3V2(PO4)3/NaV(P2O7) Heterostructure With Columnar Cluster Morphology Boosting High Capacity and Energy Density for Sodium Ion Batteries

Abstract The low energy density and sluggish Na+ diffusion in vanadium‐based polyanion cathodes have impeded further applications. Currently, a facile hydrothermal method to prepare an innovative Na3V2(PO4)3/NaV(P2O7) homogeneous cathode with columnar cluster morphology is proposed. In situ high‐temperature XRD reveals the reaction generation mechanism of the heterostructure, where konjac glucomannan (KGM) undergoes oxidative decomposition, resulting in a decrease in the oxygen content to generate (P2O7) groups. XAFS investigates the regulation of V─O bond in key length and coordination number for heterogeneous Na3V2(PO4)3/NaV(P2O7). The charge compensation mechanism is comprehensively and deeply explored by ex situ XRD/XPS/FTIR/TEM. DFT calculations and UPS/UV verify the generation of a built‐in electric field by modulating the work function of Na3V2(PO4)3 and NaV(P2O7) at the heterogeneous interface, which boosts the directional electronic transfer and significantly increases the Na+ diffusion. Meanwhile, XPS valence band spectra indicate that the difference of work function further tunes the d‐band center of vanadium toward the Fermi level, lowering the migration energy barrier of Na+. Moreover, DFT also testifies to the nearly metallic state DOS and extremely reduced energy barrier for Na3V2(PO4)3/NaV(P2O7) heterostructure. Benefiting from the unique dual‐phase structure, capacity and energy density are significantly augmented. This work provides direction and guidance for subsequent in‐depth research on homogeneous hybridized cathodes.

Effect of 4d transition-metal doping on the sensitivity of PdSSe toward NO

Abstract This study explored the adsorption stability, electronic and magnetic properties of NO adsorbed on perfect, vacancy-defected, and transition-metal (TM: Zr, Mo, and Ru) doped PdSSe through first-principles calculation methods. The results indicated that the introduction of vacancies (S- and Se-vacancy) and transition-metal doping improved the adsorption stability of NO molecule. In addition, the introduction of dopants significantly increased adsorption energy and charge transfer, and decreased the adsorption distance of NO, which suggested that the adsorption of NO on doped PdSSe was chemical adsorption. The largest change of conductivity of Zr-VSPdSSe after adsorption of NO can be used as electronic signal for detecting NO gas. Furthermore, work function of Ru-doped PdSSe exhibited obvious changes for interacting with NO molecules. These findings provide some new theoretical references for the design of new NO molecular sensors.

Synergistic Electron-Deficient Surface Engineering: A Key Factor in Dictating Electron Carrier Extraction for Perovskite Photovoltaics.

Work function modulation of transparent conductive oxides via self-assembled monolayers (SAMs) facilitates efficient hole or electron extraction in optoelectronic devices. However, recent SAMs for perovskite solar cells (PSCs) diverge from traditional interfacial dipole orientation design principles, instead leveraging electron-rich and electron-deficient surface modifications. In light of these discrepancies, this study systematically analyses electron-deficient materials of varying strength, revealing the dominance of surface modifications over interfacial dipole orientation. Specifically, modulating the electron-withdrawing strength by replacing the carboxylic acid group (Bpy-COOH) with a cyanoacrylic acid moiety (Bpy-CAA) in dual-functional bipyridine-based electron-selective molecular layers (ESMLs) enhances adsorption, electron extraction, and passivation in n-i-p PSCs. Consequently, Bpy-CAA devices achieve 23.98% efficiency, surpassing Bpy-COOH-based devices (23.20%), and maintain an impressive 21.63% efficiency in 1 cm2 cells, the highest reported for 1 cm2 n-i-p PSCs utilizing organic ESMLs. A remarkable efficiency of 26.00% is achieved by integrating Bpy-CAA as an interfacial layer into SnO2/ESML/perovskite contacts while adapting this architecture into four-terminal perovskite/silicon tandem solar cells (4T-P/STSCs) yields an impressive efficiency of 30.83%, ranking among the highest reported efficiencies for 4T-P/STSCs. Overall, this work demonstrates that the electronic nature of the molecule is more decisive than dipole orientation for efficient electron extraction, and tailoring the dual-functional ESMLs effectively facilitated the development of efficient single-junction PSCs and 4T-P/STSCs.

Triggered Photoexcited Electrons Transfer and Spin Polarization through 3dx2-y2-2pz Orbital Hybridization for Synergistic Solar-Thermal/Photocatalytic Water Purification.

Although solar steam generation has been combined with photocatalytic degradation for purifying wastewater, the inherent synergistic effects on enhancing solar-thermal water evaporation and photodegradation are poorly understood. Herein, synergistic solar-thermal and photocatalytic purification of wastewater triggered by photoexcited electron transfer and spin polarization is realized by designing a flow-bed water purification system with a bacterial cellulose/α-Fe2O3 nanodisk/carbon nanotube (BFC) composite film for the continuous solar-thermal evaporation of water and simultaneous photocatalytic degradation of organic pollutants. The photogenerated electrons in the 3dx2-y2 orbitals of the Fe atoms of α-Fe2O3 can transfer to the 2pz orbitals of the C atoms of carbon nanotubes, induced by the work function differences. The separation of photogenerated carriers is enhanced by the built-in electric field and the spin polarization effect, generating more active redox species to improve the photocatalytic degradation performance. Moreover, the photoexcited electrons injected into the carbon nanotubes can participate in solar-thermal conversion via a relaxation process to generate more heat, promoting solar steam generation performance. A flow-bed water purification system is established on the basis of the synergistic solar-thermal/photocatalytic effects for efficiently purifying various wastewater. The purified water is eligible for direct irrigation of crops without any obvious inhibition phenomena.

Buried Interface Modification for High‐Performance Perovskite Light‐Emitting Diodes

Abstract Buried interface modification strategies play a critical role in advancing the development of perovskite light‐emitting diodes (PeLEDs), which is related to charge injection, perovskite crystallization, and interfacial non‐radiative recombination. Herein, 3‐aminotetrahydrofuran hydrochloride (TAH) is employed for post‐treatment of the electron transport layer (ETL). TAH modification lowers the work function of the ETL surface, which facilitates electron injection into the perovskite layers. Besides, TAH treatment modulated the perovskite crystallization dynamics, promoting the formation of discontinuous high‐quality perovskite. Meanwhile, the multifunctional TAH chemically interacted with both the perovskite and ETL, synergistically passivating vacancy and interstitial defects. Consequently, the TAH‐modified PeLEDs achieved a peak external quantum efficiency of 22.3% with a radiance of 987.4 W sr−1 m−2. This work presents a viable approach to achieve superior carrier transport, precise morphology control, and effective defects passivation for improving the performance of PeLEDs.

MXene-Mediated Charge Modulation in Plasmonic Metal-Semiconductor Heterojunctions for Photo-Induced Enhanced Raman Spectroscopy.

The smart integration of nanoparticles with tailored semiconductors, followed by UV illumination prior to Raman measurements, activates photo-induced enhanced Raman spectroscopy (PIERS), enabling ultrasensitive detection. This photo-mediated modulation of charge transfer is a special case of surface-enhanced Raman spectroscopy (SERS), where enhancement is tuned via chemical-interaction-induced charge transfer between the analyte and substrate. Herein, photoinduced charge transfer dynamics are explored by tuning the work function of the supporting material embedding plasmonic nanostructures and creating an interfacial light-mediated charge-transfer system. Using two distinct nanoparticles supported on a two-dimensional material revealed directional charge transport behaviour, reflecting Fermi-level equilibration at heterojunctions. Titanium carbide-based MXene (Ti3C2Tx; Tx = -OH, -F) is introduced as a charge-transfer modulator due to its tunable work function, significantly influencing carrier transport direction and efficiency. Notably, Au-based hybrids exhibit PIERS enhancement upto five orders of magnitude, unlike Ag-based hybrids that show quenching. This confirms that optimized nanoparticle-MXene hybrids facilitate hot electron movement across interfaces, leading to differential PIERS responses. Additionally, density functional theory calculations elucidate electronic structures and photogenerated electron migration. This study provides valuable insights into photo-induced charge transfer, emphasizing its pivotal role in enhancing chemical contributions in SERS, advancing future optical sensing and molecular recognition platforms.

Correlation between 1H Nuclear Magnetic Resonance Chemical Shifts and Tunneling Transport in Self-Assembled Monolayer-Based Molecular Junctions.

We investigate the correlation between solution phase 1H NMR chemical shifts δ and tunneling conductance G in molecular junctions based on self-assembled monolayers (SAMs). The SAM-forming molecules are a series of four substituted oligophenylene dithiols in which π-electron delocalization is systematically varied. Molecular junctions are formed using a conducting probe atomic force microscope (CP-AFM) to make soft contact to the SAMs on Au or Ag. We observe that G exhibits an exponential correlation with the chemical shift δβ of the β-protons for each dithiol molecule, consistent with recently reported single-molecule studies. This G-δβ sensitivity is qualitatively supported by highest occupied molecular orbital (HOMO) distribution calculations, which reflect the degree of π-electron delocalization. To further explore the underlying causes, we employ an analytical off-resonance tunneling model to extract key electronic density of states parameters from the junction current-voltage (I-V) characteristics. The extracted HOMO-Fermi level offset εh is nearly constant across the molecular series, consistent with commonly observed HOMO pinning in dithiol systems, and thus there is no correlation with δβ. In contrast, the metal-HOMO electronic coupling Γ exhibits a strong exponential correlation with δβ. Thus, we establish that the cause of the exponential G-δβ correlation is the exponential Γ-δβ correlation. We also find a linear correlation between δβ and SAM work function change ΔΦ measured with a Kelvin probe. Combining the Γ-δβ and ΔΦ-δβ correlations demonstrates that Γ is exponentially correlated with ΔΦ, which measures interfacial charge transfer. First-principles calculations are necessary for thorough understanding of these correlations, but our results demonstrate that NMR chemical shifts, which reflect local atomic structure and electron densities in molecules, are a potentially powerful tool to understand connections between molecular structure, electron density, interfacial charge transfer, and electronic coupling in molecular junctions.

The impact of rumination and anhedonia on daily social and occupational function

ABSTRACT Introduction Rumination (repetitive negative thinking; RNT) and anhedonia are hallmark features of depression and other psychiatric disorders known for their association with executive functioning. However, limited work has directly evaluated associations between these indices and their potential contribution to impairments in social and occupational function. This study investigated cross-sectional and longitudinal associations between RNT and anhedonia with functional outcomes at 6- and 12-months among individuals with elevated depression or anxiety symptoms. Method Participants (N = 92, AgeM[SD] = 22[2.9], 72% female) completed Hamilton Depression and Anxiety Rating Scales, Perseverative Thinking Questionnaire (RNT), Snaith-Hamilton Pleasure Scale, Social Adjustment Scale (SAS-SR), and Health and Work Performance Questionnaire (HPQ). Participants also completed 7-day daily-diaries capturing social and occupational function; SAS-SR, HPQ, and daily-diaries were repeated at 6- and 12-months. General linear models evaluated baseline associations and linear mixed models tested longitudinal effects of baseline RNT and anhedonia on functional outcomes. Depression, anxiety, age, and sex-at-birth were covaried. Results At baseline, RNT and anhedonia were associated with lower global and social function, and greater work impairment (ps ≤ .03). Daily diaries showed baseline associations between anhedonia and lower social satisfaction (p = .04) and RNT and greater work impairment (p = .01). Function generally improved over time (ps ≤ .03), and baseline associations with anhedonia tended to diminish (ps < .001). By contrast, baseline RNT continued to impact global, social, and work function and absenteeism (ps ≤ .01) at 12-months. Per daily diaries, baseline RNT predicted reduced social satisfaction (p = .01) and elevated work impairment 12 months later (p = .04). Conclusions There were independent clinically significant associations for both anhedonia and RNT with multiple aspects of functioning. Some functional improvements occurred over time, accompanied by attenuated relationships with anhedonia. In contrast, RNT to functioning relationships persisted over 12 months.

3D Topological Inorganic Electrides: Screening, Properties, and Applications.

The convergence of inorganic electrides and topological quantum phenomena has ushered in novel paradigms for designing advanced quantum materials. While low-dimensional (0-2D) topological inorganic electrides have garnered considerable attention, their three-dimensional (3D) counterparts-featuring intricate interstitial electron networks-remain entirely uncharted territory. Herein, the identification of twelve 3D inorganic electrides within the rare-earth hydride family is reported, nine of which are previously unreported. First-principles calculations reveal a diverse magnetic landscape: two systems exhibit ferromagnetic ordering, while seven demonstrate antiferromagnetic configurations. Strikingly, these materials host rich topological states, encompassing nodal points, nodal lines, and associated surface signatures such as Fermi arcs and drumhead-like states. When spin-orbit coupling is introduced, the magnetic ordering breaks time-reversal symmetry, thereby generating substantial Berry curvature and resulting in a relatively large anomalous Hall conductivity (939 Scm-1). Furthermore, these inorganic electrides exhibit ultralow work functions (2.6-3.9eV) on rare-earth-terminated surfaces. Under external electric fields, the 3D interstitial electrons migrate to the surface, forming a quasi-2D electron gas. Significantly, such low work functions can effectively activate N2, enhancing catalytic NH3 synthesis. These findings establish an ideal platform to explore 3D inorganic electrides, along with their topological features, anomalous transport phenomena, low work functions, and NH3 synthesis.

Evaluation of Au Nanoparticle Catalysts Supported on Metal Oxide for the Catalytic Reduction of 4-NP.

4-Nitrophenol (4-NP) pollution in the chemical, dye, and other industries poses significant risks to humans and aquatic organisms. In this study, we prepared metal oxide-supported gold nanoparticles (AuNPs/Al2O3, AuNPs/TiO2, and AuNPs/ZnO) and applied them to the catalytic reduction of 4-NP. The Bader charge and differential charge, dos and d band centers, work function, and reaction free energy of AuNP composites were analyzed through DFT calculations. The influence of metal oxide carriers on the catalytic activity of AuNPs was explored, which decreased in the following order: AuNPs/Al2O3 > AuNPs/TiO2 > AuNPs/ZnO. In addition, the catalytic reduction performance of these AuNP composites for 4-NP in the presence of NaBH4 was investigated. The results showed that the AuNPs/Al2O3 catalyst exhibited the best performance (3.62 ± 0.17 min-1), consistent with the theoretical calculations. Meanwhile, the AuNPs/Al2O3 catalyst exhibited good reusability. More relevantly, the catalytic reduction mechanism of metal oxide-supported AuNPs for 4-NP was proposed from both experimental and theoretical calculations.

Bifunctional Pt-based alloys for furfural electro-oxidation coupled with green hydrogen production.

Bifunctional Pt-based alloys for furfural electro-oxidation coupled with green hydrogen production.

Optimizing Surface Electronic Structure by Ba Dispersion for Enhanced High-Temperature Oxygen Evolution Reaction Activity.

Surface modification is an advanced strategy to engineer and optimize the work function of the perovskite oxides, which can influence the surface electron and ion transfer processes and tune the surface adsorption of the reaction intermediates, thus enhancing the catalytic activity by creating more active sites. Herein, we modify the surface electronic structure of the Pr0.9CoO3-δ anode of the solid oxide electrolysis cells (SOECs) by the high-temperature dispersion of Ba species. Comprehensive structural and electrochemical characterizations, along with in situ characterizations and density functional theory calculations, reveal that Ba dispersion significantly enhances the surface d-p orbital hybridization between Co and O atoms and thus weakens Co-O bond covalency, facilitating oxygen vacancy formation and oxygen ion mobility. Electrochemical testing demonstrates that the Ba-dispersed anode exhibits significantly reduced polarization resistance and superior high-temperature oxygen evolution reaction activity with a current density of 3.36 A·cm-2 at 1.6 V and 800 °C. These findings provide a novel strategy for engineering surface electronic structures to enhance SOEC performance, offering insights into rational catalyst design for efficient energy conversion applications.

Curtailing Non-Radiative Recombination and Tailoring Interfacial Energetics via Bimolecular Passivation toward Efficient Inverted Perovskite Solar Cells.

Despite significant development of perovskite solar cells (PSCs) in recent years, presence of nonradiative recombination centers at the perovskite surface, grain boundaries, and interfaces remain a major bottleneck in achieving the desired device performance. Also, energy levels offset among perovskite and neighboring functional layers leads to poor charge extraction, thereby further limiting the device capability. Therefore, it is essential to carefully understand the underlying defects and develop a suitable passivation technique to suppress such detrimental imperfections. Herein, we propose a synergistic bimolecular passivation strategy to simultaneously reduce the trap states density, enhance crystallinity and improve interfacial charge transfer in inverted (p-i-n) PSCs. The poly(2-ethyl-2-oxazoline) (PEOXA) introduced in the antisolvent modulates the crystallization kinetics and concurrently passivates the grain boundaries and surface defects of perovskite films. In addition, a simple surface post-treatment of the perovskite layer using 3-(aminomethyl)pyridine (3-APy) suppresses contact-induced interfacial recombination as a consequence of lowered work function in the surface region. This synergistic passivation approach renders enhanced defect passivation and improved interfacial energetics, leading to a significant suppression in undesirable nonradiative recombinations and improvement of interfacial charge transfer. Consequently, the power conversion efficiency (PCE) of the devices significantly improves from 22.01 to 24.65% (with a certified PCE of 24.01%), while the operational stability at the maximum power point is maintained at a decent value for over 1000 h of continuous illumination. This work provides a guideline for developing multimolecular passivation approaches to selectively target various defects toward improved performance of perovskite optoelectronic devices.

Working with the Socially Vulnerable – An Observational Cross-Sectional Study Investigating the Association between Exposure to Socially Vulnerable Patients and Symptoms of Burnout in Ambulance Personnel

Objectives In Scandinavia, ambulance operations involving socially vulnerable patients, i.e., mentally ill, neglected or marginalized patients, have been highlighted as one of the most demanding challenges for the future prehospital work. However, little is known about the mental health implications of working extensively with this patient group. This study aims to investigate the proportion of operational tasks within the Danish prehospital setting that involve working with socially vulnerable patients, and whether there is a significant positive association between the workload involving socially vulnerable patients and the level of burnout symptoms among ambulance personnel. Methods This observational cross-sectional study is based on data from the project “You Don’t Stand Alone,” using baseline data collected through validated questionnaires completed by a sample of 451 ambulance personnel. Descriptive analyses were conducted to investigate the proportion of operational tasks involving socially vulnerable patients, and linear regression models were utilized to analyze the associations between exposure to socially vulnerable patients and burnout. Results In this study, we found that 98.5% of the ambulance personnel were involved in operational tasks with socially vulnerable patients, and that 24% of the participants had experienced more than 20 incidents with at least one of the three subgroups of socially vulnerable patients throughout the past year. Furthermore, we found that workload involving socially vulnerable patients was positively associated with the level of burnout (B = 2.05, SE = .28, t(432) = 7.31, 95% CI: 1.50–2.60), and that age and bonding social capital were protective factors, whereas specific work functions were associated with an increased level of burnout. We also found that the significant association between workload involving socially vulnerable patients and levels of burnout attenuated to a non-significant level when adjusting for overall workload of additional critical incidents. Conclusions The load of socially vulnerable patients in the operational work of ambulance personnel is important to consider due to its potential mental strain. The findings from this study emphasize the relevance of the potential strain of working with these groups of patients, but also highlights that this type of operational tasks is just one of many demanding exposures in ambulance work.

Ultrabright LaB6 nanoneedle field emission electron source with low vacuum compatibility

An electron source with high performance and low vacuum compatibility is urgently in demand for the electron-beam instruments. However, there exists compromise between high brightness, small energy spread, and low vacuum for the commercial electron sources. To overcome this challenge, here we use a self-heating effect to stabilize the single-crystalline LaB6 nanoneedle point field emitter under low vacuum. An ultrahigh reduced brightness of 1012 A/m2/sr/V which is three orders of magnitude higher than commercial W field emitter and with monochromatic energy spread of 0.5 eV were calculated at a large current of 2 μA, showing a stable emission with fluctuation of 3.4%/hour in a low vacuum at 7 × 10−6 Pa which is three orders of magnitude lower than the operating environment of commercial W field emitter. The ultrahigh brightness and small energy spread are attributed to the sharp, robust structure and low work function of LaB6 nanoneedle made by focused ion beam.

Establishing Ohmic contact with ultra-thin semiconductor layer through magnetron sputtering for dendrite-free Zn metal batteries.

Establishing Ohmic contact with ultra-thin semiconductor layer through magnetron sputtering for dendrite-free Zn metal batteries.

Plasmon assisted generation of solvated electrons from low work function scandium oxide and their utilization for enhanced nitrogen reduction

Plasmon assisted generation of solvated electrons from low work function scandium oxide and their utilization for enhanced nitrogen reduction