Precise control over thin-film morphology and interfacial organization is essential for solution-processed organic electronics. We demonstrate the successful Langmuir-Blodgett (LB) fabrication of nanometer-precise, uniform PM6 and N2200 polymer films. Optimized solvent and spreading conditions yield controlled assembly of uniform and homogeneous mono- and multilayers. PM6 formed isotropic films with tangled coiled structures, while N2200 showed anisotropic domains with directional π-stacking and extended branch-like polymer chains. Nanomechanical analysis revealed a 35-40% increase in surface elasticity for multilayers versus monolayers. Surface potential measurements underlined a thickness-dependent transition from substrate-dominated electrostatics in monolayers to a bulk-like behavior in multilayers, while photoluminescence mapping confirms preservation of emissive functionality even down to a monolayer. Preliminary photoresponsivity tests with photoactive layers below 20 nm show a reproducible increase in short-circuit current density upon increasing the number of PM6 and N2200 layers from five to six each, as confirmed by measurements across multiple devices. This trend is attributed to an absorption cross section that scales with increasing layer thickness. Our results position the LB method as a robust platform for constructing ultrathin, structurally coherent, and electronically active polymer interfaces with nanometer-scale thickness control.

The inherent susceptibility of n-type organic semiconductors to molecular dioxygen (O2) results in electron trapping or in unintended p-doping, which in turn diminishes their electron mobility. This concept is challenged in the present study by exploring O2 interactions with organic charge-transfer complexes (CTCs), where electron donor-acceptor interactions generate partially delocalized electronic states. Using a CTC comprising a phenazine electron donor and a 7,7,8,8-tetracyanoquinodimethane (TCNQ) electron acceptor, we demonstrate that its exposure to O2 does not lead to electron extraction but instead enhances the charge-transfer activity. The increased electron density at the TCNQ acceptor upon CTC exposure to O2 is attributed to electron trap-states passivation by O2, without evidence of chemisorption. This passivation mitigates recombination losses, resulting in a threefold photoluminescence quantum yield increase, enhanced electrical conductivity, and improved charge-transfer state efficiency. Similar O2-mediated conductivity enhancements are observed across additional donor-acceptor pairs, proving the broader applicability of this effect, and paving the way for designing O2-enhanced advanced organic electronic materials.

Scanning transmission x-ray microscopy (STXM) is a nanoscale imaging technique that can utilize several powerful contrast mechanisms for the quantitative mapping of chemical and physical materials properties. Spatial resolutions down to 7 nm at the soft x-ray energy range have been demonstrated. A limiting factor for high-resolution STXM imaging is given by the positioning precision of the sample with respect to the focusing optic, with the current state-of-the-art leading to significant overheads, especially at low pixel dwell times, and being vulnerable to unavoidable external vibration sources. In this work, we present a method called supersampled scanning microscopy that allows for a significant reduction of overhead times while simultaneously removing the effects of vibrational noise by sampling the position of the sample at a rate significantly higher than the vibration spectrum and reconstructing the sample transmission image from the recorded list of positions and detector counts. We demonstrate the performance of the technique with a set of proof-of-concept high-resolution imaging experiments.

The performance of photoresists is a major challenge in extreme ultraviolet (EUV) lithography and needs to be improved for the future technology nodes that require higher resolution, patterning fidelity, and sensitivity. Hybrid inorganic/organic materials are considered for this crucial function, but the chemical mechanisms underlying their solubility switching are not well understood, which hampers the rational improvement of EUV photoresists. Here we study n-butyltin-oxo cages, a readily accessible "open source" representative negative tone resist. Upon exposure to EUV radiation (wavelength 13.5 nm), butane, butene and octane are the main volatile reaction products. Tin is fully retained in the films even after prolonged EUV exposure. It is found that the loss of only similar to 18% of the butyl groups suffices to render the resist film insoluble. The initial quantum efficiency of Sn-C bond cleavage is Phi approximate to 5 per absorbed EUV photon, but this decreases rapidly with conversion of the material. After the primary Sn-C bond cleavage in a tin-oxo cage, induced by photoionization or capture of a (secondary) photoelectron, facile thermal reaction steps may occur that lead to additional Sn-C bond breaking. Although many questions remain, our work sheds new light on the reaction mechanisms at play and provides input for simulations of the lithographic process.

ABSTRACT The introduction of magnetic microbeads has greatly advanced biomedical research by enabling high‐precision methods for cell sorting, biomolecule transport, and cell force analysis. Applications extend to molecular isolation, diagnostic assays, and targeted drug delivery. Torques observed on superparamagnetic microbeads during cell experiments indicate spatial variations in the microbead properties. A high degree of internal magnetic structure complexity is revealed by nanoscale 3D imaging of superparamagnetic microbeads via soft X‐ray laminography. Microbeads are found to have an uneven distribution of magnetic magnetite nanoparticles. The effects of this on the hydrodynamic behavior of the microbeads are analyzed by semi‐numerical simulations using the laminography data. The calculated magnitudes of magnetic torque are consistent with the data from microbead transport experiments, involving fibroblast cells. By this, a structural basis for magnetic torques observed in experiments with superparamagnetic microbeads has been identified. Soft X‐ray laminography is proven to be a powerful technique for revealing structural details important to lab‐on‐a‐chip technologies. The findings indicate that magnetic microbeads deviate considerably from the theoretical model of uniform spheres. The identified structural heterogeneities hold significant implications for lab‐on‐chip experiments.

Soft x-ray ptychography is becoming a key synchrotron microscopy technique in the fields of condensed matter physics, chemistry, and environmental and life sciences. Its attractiveness across broad disciplinary fields is owed to the favorable combination of high spatial resolution and strong contrast mechanisms. The SOft X-ray Ptychography Highly Integrated Endstation (SOPHIE) at the Swiss Light Source (SLS) was developed to accommodate soft x-ray ptychography experiments requiring high spatial resolution, in addition to high chemical and ferroic sensitivities. An introduction to soft x-ray ptychography with SOPHIE aimed at prospective users is provided. Furthermore, an overview of the instrumentation of SOPHIE is given along with an example of the imaging capabilities, which demonstrate the achievement of a sub-10 nm spatial resolution at a photon energy of 706 eV.

Organometallic tin-oxo-hydroxo cage compounds offer a promising photoresist platform for extreme ultraviolet photolithography (EUVL). Their reactivity is dominated by the facile breaking of the tin-carbon bonds upon photon or electron irradiation. As the cage is dicationic, it exists as a complex with anions for charge compensation. In the present work, we explore the n-butyltin-oxo cage with two tetrakis(pentafluorophenyl)borate counteranions (TinPFPB). In contrast to the small counterions that are typically used, the bulky PFPB anion absorbs a substantial fraction (similar to 30%) of the impinging EUV radiation (13.5 nm, 92 eV), and it has its own reactivity upon photoionization. When thin films of the complex are irradiated with EUV radiation at low doses, a positive-tone development is possible, which is rather unique as all other known tin-oxo cage resists show a negative tone (cross-linking) behavior. We propose that the initial positive tone behavior is a result of the chemical modification of the Sn cluster by fragments of the borate anions. For comparison, we include the tetrakis(p-tolyl)borate anion (TB) in the study, which has similar bulkiness, and its complex with the n-butyltin-oxo cage (TinTB) shows the usual negative tone EUV resist behavior. This negative-tone behavior for our control experiment rules out a hypothesis based purely on the steric hindrance of the anion as the cause of the different EUV reactivity.

beta-SiC nanoparticles are one of the most common reinforcements in Mg-Al alloy matrix nanocomposites (MgMNCs). The interfacial interactions between beta-SiC and the alloy matrix are complex due to the occurrence of new phases and the fine scale of the 3D architecture. This study aims to explore the feasibility of using synchrotron Scanning Transmission X-ray spectro-Microscopy (STXM) to investigate such interfacial interactions and acquire reference X-ray Absorption Spectroscopy (XAS) data for some common interphase crystals present within the composites, which are not readily available. Throughout this study, a reliable procedure for collecting STXM data on samples derived from MgMNCs was developed, and reference XAS spectra for alpha-Mg, beta-Mg17Al12, T2-Al2MgC2, Mg2Si and MgO present in MgMNCs were collected. The accessibility of STXM and spatially resolved XAS spectrum is not only useful for nanocomposite alloy research but applicable widely across the magnesium alloy research community when identifying and quantifying the phases with complex crystal structures and oxide states.

The relationship between the nanomorphology and the charge transport characteristics in solution-processed organic thin films has been the focus of extensive research, as it is key to the further advancement of organic photovoltaics. Understanding the nanostructured domains and their dependence on the applied thermal annealing conditions is one crucial challenge. Here, the conjugated small-molecule donor p-DTS(FBTTh2)2 is used as a model system to demonstrate how isothermal annealing alone, without addition of any processable additives during solution casting, leads to a high ordering of domain structures. Using scanning transmission X-ray microspectroscopy (STXM), the domain structures are probed at the resonance energy of 284.7 eV corresponding to the C1s to Pi* transition. The STXM data analysis reveals the in-plane orientation of the conjugated backbone comprising the heterocyclic aromatic compounds dithienosilole (DTS), bithiophene (BT), and fluorobenzothiadiazole (FBT). The analysis further exhibits the presence of ordered domains accompanied by the disordered boundaries in thin films where the increase in the domain sizes and the high degree of molecular order (anisotropy) is associated to the relatively slow crystallization dynamics of p-DTS(FBTTh2)2 molecules during isothermal annealing at 90 °C. The analysis of the out-of-plane component of the directed resonance intensity shows deviations in the local out-of-plane tilt angles to the lower values, for the most ordered regions in the thin film, suggesting the more out-of-plane orientation of Pi* resonance. These results manifest a promising role of STXM technique in enhancing the knowledge of domain structures in small molecule organic semiconductors.

Controlling drug release rate and providing physical and chemical stability to the active pharmaceutical ingredient are key properties of oral solid dosage forms. Here, we demonstrate a formulation strategy using phase-separated polymer blends where the morphology provides a route for tuning the drug release profile. By utilising phase separation of a hydrophobic and a hydrophilic polymer, the hydrophilic component will act as a channelling agent, creating a porous network upon dissolution that will dictate the release characteristics. With ptychographic X-ray tomography and scanning transmission X-ray microscopy we reveal how the morphology depends on both polymer fraction and presence of drug, and how the drug is distributed over the polymer domains. Combining X-ray imaging results with dissolution studies reveal how the morphologies are correlated with the drug release and showcase how tuning the morphology of a polymer matrix in oral formulations can be utilised as a method for controlled drug release. Drug delivery via solid oral dosage requires a controlled release rate and physical and chemical stability of the drug within the formulation. Here, X-ray tomography and spectromicroscopy reveal how the morphology of a phase-separated polymer blend controls drug release.

K-edge photoexcitation of n -butyltin-oxo cage photoresist cores leads to (multiple) ionization and butyl group loss.

The direct integration of 1D magnetic nanostructures into electronic circuits is crucial for realizing their great potential as components in magnetic storage, logical devices, and spintronic applications. Here, we present a novel template-free technique for producing magnetic nanochains and nanowires using directed self-assembly of gas-phase-generated metallic nanoparticles. The 1D nanostructures can be self-assembled along most substrate surfaces and can be freely suspended over micrometer distances, allowing for direct incorporation into different device architectures. The latter is demonstrated by a one-step integration of nanochains onto a pre-patterned Si chip and the fabrication of devices exhibiting magnetoresistance. Moreover, fusing the nanochains into nanowires by post-annealing significantly enhances the magnetic properties, with a 35% increase in the coercivity. Using magnetometry, X-ray microscopy, and micromagnetic simulations, we demonstrate how variations in the orientation of the magnetocrystalline anisotropy and the presence of larger multi-domain particles along the nanochains play a key role in the domain formation and magnetization reversal. Furthermore, it is shown that the increased coercivity in the nanowires can be attributed to the formation of a uniform magnetocrystalline anisotropy along the wires and the onset of exchange interactions.

We report, for the first time, sub-4 nm mapping of donor : acceptor nanoparticle composition in eco-friendly colloidal dispersions for organic electronics. Low energy scanning transmission electron microscopy (STEM) energy dispersive X-ray spectroscopy (EDX) mapping has revealed the internal morphology of organic semiconductor donor : acceptor blend nanoparticles at the sub-4 nm level. A unique element was available for utilisation as a fingerprint element to differentiate donor from acceptor material in each blend system. Si was used to map the location of donor polymer PTzBI-Si in PTzBI-Si:N2200 nanoparticles, and S (in addition to N) was used to map donor polymer TQ1 in TQ1:PC71BM nanoparticles. For select material blends, synchrotron-based scanning transmission X-ray microscopy (STXM), was demonstrated to remain as the superior chemical contrast technique for mapping organic donor : acceptor morphology, including for material combinations lacking a unique fingerprint element (e.g. PTQ10:Y6), or systems where the unique element is in a terminal functional group (unsaturated, dangling bonds) and can hence be easily damaged under the electron beam, e.g. F on PTQ10 donor polymer in the PTQ10:IDIC donor : acceptor blend. We provide both qualitative and quantitative compositional mapping of organic semiconductor nanoparticles with STEM EDX, with sub-domains resolved in nanoparticles as small as 30 nm in diameter. The sub-4 nm mapping technology reported here shows great promise for the optimisation of organic semiconductor blends for applications in organic electronics (solar cells and bioelectronics) and photocatalysis, and has further applications in organic core-shell nanomedicines.

Once emitted into the environment, macro- (MaP), micro- (MP) and nanoplastics (NP) are exposed to environmental weathering. Yet, the effects of biogeochemical weathering factors occurring in the soil environment are unknown. As the transport, fate, and toxicity of MP and NP depend directly on their surface properties, it is crucial to characterize their transformation in soils to better predict their impact and interactions in this environment. Here, we used scanning transmission x-ray micro spectroscopy to characterize depth profiles of the surface alteration of environmental plastic debris retrieved from soil samples. Controlled weathering experiments in soil and with UV radiation were also performed to investigate the individual effect of these weathering factors on polymer surface alteration. The results revealed a weathered surface on a depth varying between 1 µm and 100 nm in PS, PET and PP environmental plastic fragments naturally weathered in soil. Moreover, the initial step of surface fragmentation was observed on a PS fragment, providing an insight on the factors and processes leading to the release of MP and NP in soils. The comparison of environmental, soil incubated (for 1 year) and UV weathered samples showed that the treatments led to different surface chemical modifications. While the environmental samples showed evidence of alteration involving oxidation processes, the UV weathered samples did not reveal oxidation signs at the surface but only decrease in peak intensities (indicating decrease of the number of chemical C bonds). After a one-year incubation of samples in soil no clear aging effects were observed, indicating that the aging of polymers can be slow in soils.

Here efficient organic photovoltaic devices fabricated from water-based colloidal dispersions with donor:acceptor composite nanoparticles achieving up to 9.98% power conversion efficiency (PCE) are reported. This high efficiency for water processed organic solar cells is attributed to morphology control by surface energy matching between the donor and the acceptor materials. Indeed, due to a low interfacial energy between donor and the acceptor, no large phase separation occurs during the nanoparticle formation process as well as upon thermal annealing. Indeed, synchrotron-based scanning transmission X-ray microscopy reveals that the internal morphology of composite nanoparticles is intermixed as well as the active layer morphology after thermal treatment. The PCE of this system reaches 85% that of devices prepared from chlorinated solvent. The gap between water-based inks and organic solvent-based inks gets narrower, which is promising for the development of eco-friendly processing and fabrication of organic photovoltaics.

Crystalline organic semiconducting thin films from the benchmark molecule C8-BTBT-C8 were obtained using physical vapor deposition and various solution-based methods. Utilizing atomic force microscopy and X-ray spectromicroscopy, we illustrate the influence of the underlying growth mechanism and determine the highly preparation-dependent orientation of the thiophene backbone. We observe a continuous trend for crystalline C8-BTBT-C8 thin film domains to extend into the square millimeter-range under near-equilibrium growth conditions. For such well-defined systems, electron diffraction tomography allows us to precisely determine the unit cell directly after film deposition and to reveal an 8° molecular tilt angle with respect to the surface normal. This finding is in almost perfect accordance with the values derived from near-edge X-ray absorption fine structure linear dichroism. Within this work, we shine a light on both the successes and challenges connected to the realization of potent, thiophene-based semiconducting films, paving the way toward square centimeter-sized ultrathin organic crystals and their application in organic circuitry.

The absorption of extreme ultraviolet (EUV) radiation by a photoresist strongly depends on its atomic composition. Consequently, elements with a high EUV absorption cross section can assist in meeting the demand for higher photon absorbance by the photoresist to improve the sensitivity and reduce the photon shot noise induced roughness. In this work, we enhanced the EUV absorption of the methacrylic acid ligands of Zn oxoclusters by introducing fluorine atoms. We evaluated the lithography performance of this fluorine-rich material as a negative tone EUV photoresist along with extensive spectroscopic and microscopic studies, providing deep insights into the underlying mechanism. UV–vis spectroscopy studies demonstrate that the presence of fluorine in the oxocluster enhances its stability in the thin films to the ambient atmosphere. However, the EUV photoresist sensitivity (D50) of the fluorine-rich oxocluster is decreased compared to its previously studied methacrylic acid analogue. Scanning transmission X-ray microscopy and in situ X-ray photoelectron spectroscopy in combination with FTIR and UV–vis spectroscopy were used to gain insights into the chemical changes in the material responsible for the solubility switch. The results support decarboxylation of the ligands and subsequent radical-induced polymerization reactions in the thin film upon EUV irradiation. The rupture of carbon–fluorine bonds via dissociative electron attachment offers a parallel way of generating radicals. The mechanistic insights obtained here will be applicable to other hybrid materials and potentially pave the way for the development of EUV materials with better performance.