Lead mixed-halide perovskite nanocrystals offer exceptional optical properties but suffer from ionic instability and ion migration under external stimuli, challenging their integration into devices. While such effects have been well studied in individual NCs and films, their impact on nanocrystal assemblies remains less understood. Here, we investigate the effect of strong external electric fields on self-assembled CsPbBr2.4Cl0.6 nanocrystal superlattices. By positioning individual superlattices between micrometer-sized capacitor plates, we analyze field-induced changes in photoluminescence, elemental composition, and morphology. We observe position-dependent changes in emission energy correlated with halide ion redistribution, revealed by energy-dispersive X-ray analysis, resulting from a nonuniform electric field across the superlattice, and supported by finite-element simulations. In situ mass spectrometry detects bromide sublimation, suggesting a combination of inter- and intraparticle halide diffusion. Irreversibility of photoluminescence and morphological changes further support a field-driven reorganization. These findings reveal responses of CsPbBr2.4Cl0.6 superlattices subject to external electric fields, relevant for their implementation in optoelectronic applications.

Supercrystals of lead-halide perovskite nanocrystals combine the semiconducting properties of bulk perovskites with quantum confinement effects and extend them to the macroscopic scale. Supercrystals assembled via a two-layer phase diffusion process using an acetonitrile antisolvent were recently shown to be unusually robust. We investigate how the acetonitrile-assisted self-assembly process influences surface chemistry, the atomic lattice of nanocrystals, and the structure of the supercrystal. Using quantitative NMR spectroscopy, nanofocused X-ray diffraction, and optical spectroscopy, we show that a reduced density of the ligand shell caused by the exposure to acetonitrile in the assembly underlies the mechanical robustness of these supercrystals. Ligand stripping further drives a highly size-selecting lateral growth of the supercrystal and induces anisotropic relaxation of the nanocrystal atomic lattice while preserving the electronic coupling and robust light-emitting properties of the assembly. That enables the mechanical manipulation of supercrystals such as stacking, thereby opening new avenues for integration into optoelectronic devices.

ABSTRACT Two‐dimensional organic‐inorganic hybrid perovskites (2D OIHPs), with their unique soft lattice and versatile polarization tunability, offer an exceptional platform for exploring Rashba spin‐orbit coupling (SOC). While in‐plane Rashba SOC and ferroelectricity have been extensively studied, the out‐of‐plane Rashba SOC combined with out‐of‐plane ferroelectricity is more desirable for realizing low‐power, multifunctional, non‐volatile spintronic devices. Here, we synthesize single‐crystalline, phase‐switchable polar 2D OIHPs within a PDMS‐based sealed space and reveal the transition process between the two polar structures. The complex polar structure enables the sequential emergence of out‐of‐plane Rashba spin polarization and out‐of‐plane ferroelectric order. By manipulating the anomalous Rashba splitting with electric and magnetic fields in the LT phase, we directly reveal the dominant role of momentum offset in Rashba exciton recombination. Furthermore, we develop a self‐powered photodetector exhibiting chiral‐light selectivity and achieve reversible electrical control over the electron spin texture orientation in the RT phase. These findings establish a new material paradigm for electrically tunable spin‐photonics and low‐power spintronic devices.

Explorative chemistry in a reaction system composed of NbI4, Li2(CN2), and Li2O has led to the discovery of a number of niobium oxyiodide cluster compounds. During this reaction, the formation of solid phases was detected alongside gaseous phases, resulting in a range of products with cluster cores of varying shapes. After several niobium oxyiodide cluster compounds have already been identified within this reaction system, two additional compounds, Nb6O3I15 and Nb11O6I24, are discovered and structurally characterized by single-crystal X-ray diffraction. Both structures are based on the butterfly-shaped, oxygen-capped niobium cluster [Nb4O], which is extended to larger cluster fragments. The [Nb4O] cluster core in Nb6O3I15 is extended by two [NbO] units to form a three-dimensional framework, and Nb11O6I24 contains two connected [Nb4O] units, which form chiral units within an antiferrochiral hexagonal packing of strings. The striking string-like character of Nb11O6I24 was investigated in terms of its electronic structure and properties. DFT calculations showed Nb11O6I24 to possess a zero indirect band gap, with a pair of 3-dimensional flat bands surrounding the Fermi level. These unusual features of the electronic band structure suggest the presence of strongly correlated intercluster singlet electron states, arising from the helical shape of the clusters, the hexagonal packing of the strings, and the delocalized nature of cluster electron wave functions.

We report the chiroptical properties of enantiopure [2.2]fluorenonophane measured using electronic circular dichroism and circularly polarized luminescence spectroscopy. The target compound exhibited excellent chiroptical properties with high dissymmetry factors of gabs = ±1.3 × 10-2 and glum = +2.5 × 10-2/-2.6 × 10-2 in a wide range of solvents, accompanied by strong indications of excimer formation. This study emphasizes the outstanding role of [2.2]paracyclophanes as model systems for small molecules with relatively large CPL and expands this compound class by using the easily accessible and modifiable fluorenone derivative.

We present Transient Absorption Processing and Analysis Software (TAPAS), an open-source, Python-based graphical platform that covers the entire transient absorption (TA) workflow, from raw data import and preprocessing to visualization, global and target fitting, and statistical evaluation. Users operate TAPAS through an intuitive, seven-tab GUI, yet all underlying modules remain accessible for inspection and extension, merging GUI convenience with script-level flexibility. The fitting engine employs just-in-time compilation via an open-source machine learning compiler ecosystem, delivering two-20-fold speed gains over established packages. Automatic differentiation and residual-based effective-sample-size calculations yield reliable confidence intervals and correlation matrices, while an integrated sampling routine provides full Bayesian posterior exploration-diagnostics which are rarely available in other TA tools. All raw, processed, and fitted data are written to standardized Hierarchical Data Format 5 containers and automatically annotated with rich metadata, ensuring complete provenance. An extended case study on Rose Bengal shows how TAPAS first reveals hidden lifetime correlations, then employs broadband global and target analysis to merge TA traces with complementary steady-state and literature data, yielding a single, self-consistent kinetic model. By uniting advanced uncertainty quantification and transparent data management within a user-friendly interface, TAPAS closes the gap between accessibility and rigorous statistical treatment in TA spectroscopy.

In this study, we investigate the time-resolved photodetection characteristics of multilayer WSe 2 films fabricated via roll-to-roll mechanical exfoliation. By systematically studying the bias and irradiance dependence of the photocurrent dynamics, and by employing spatially resolved photocurrent mapping, we provide insights into the mechanisms governing the device response. We demonstrate a pronounced irradiance dependence of the response times and reveal decay times of 9.8 ns as well as 3 dB electrical bandwidths exceeding 50 MHz, rendering these devices on par with high-quality, manually exfoliated WSe 2 photodetectors. These results establish roll-to-roll exfoliation as a powerful and scalable fabrication technique capable of producing high-speed photodetectors.

Lead halide perovskite nanocrystals (NCs) are promising materials for light-emitting diodes (LEDs) due to their wavelength tunability, narrow emission line width, and high photoluminescence quantum yield. Oftentimes, these devices suffer from charge carrier imbalance and reduced charge injection because as-synthesized NCs are covered by long aliphatic ligands. Here, we report ligand exchange to small electron-withdrawing or -donating cinnamate ligands. We probe the influences of the ligands' inductive effect on hole injection by photoluminescence spectroelectrochemistry (PL SEC). We find that hole injection into NCs covered by electron-withdrawing ligands is facilitated, and hole-only devices exhibit higher currents compared to electron donating ligands. Our work highlights the potential of PL SEC as a powerful tool to rationalize the performance of lead halide perovskite NCs in LEDs.

Cesium lead bromide perovskite nanocrystals (NCs) covered with lecithin ligands in liquid toluene suspensions were investigated with a range of complementary scattering techniques and nuclear magnetic resonance to reveal their surface chemistry, solution structure, and diffusive dynamics. Distinct self-diffusion coefficients were determined and analyzed, namely the center-of-mass diffusion of the NCs and of coexisting ligand micelles, as well as the lateral diffusion of the l-α-lecithin ligand relative to the NC surface and within the micelles. We find a dynamic surface equilibrium, represented by a tunable lateral diffusion coefficient dependent on the ligand surface density. This phenomenon can be rationalized by the extraordinary binding of this zwitterionic ligand and its ability to bind via two different binding sites. These results highlight the dynamic nature of the ligand binding to lead halide perovskite NCs.

Lead halide perovskite nanocrystals are of interest for the application as emissive layer in light emitting diodes (LEDs) due to their high photoluminescence quantum yield, their color tunability and their defect tolerance. For the application in LEDs, charges need to be easily transferred from the charge transport layers to the nanocrystal core without compromising their optoelectronic properties. While charging of nanocrystals can be studied by spectroelectrochemistry (SEC) in general, in this work we combine SEC with diffraction-limited optical resolution. This allows studying hole injection into self-assembled supercrystals of CsPbBr3 nanocrystals and determining the spatially dependent potential for this action. We find an overall brightening of the photoluminescence, which is gradually shifting from the edges to the supercrystal center, and a generally greater resistance toward electrochemical degradation in the supercrystals.

The continued miniaturization of microelectronic systems requires new strategies for fabricating microelectronic materials beyond conventional lithography and metal evaporation. Metalloid nanoclusters offer promising alternatives for printing and patterning conductive and semiconductive elements. Here, we report on the synthesis, structural characterization, and first application of the soluble metalloid germanium cluster Ge14Br8(PnPr3)4, obtained via controlled disproportionation of a metastable GeBr solution. Substitution of the phosphine ligands markedly enhances the solubility in organic solvents, enabling comprehensive spectroscopic characterization via nuclear magnetic resonance (NMR), ultraviolet-visible (UV-vis), and mass spectrometry. Furthermore, the cluster demonstrates a high Ge content of 45 wt %, rendering it a possible precursor for laser-induced writing of elemental germanium under inert conditions. To demonstrate its potential, we fabricate deliberately designed patterns of Ge microstructures and assess their semiconducting behavior. This work establishes the first example of direct laser writing of germanium from a soluble metalloid cluster precursor, opening new pathways for additive microfabrication in semiconductor technology.

We compare the fluorescence properties of CsPbBr2Cl nanocrystals, obtained via two distinct synthetic procedures and self-assembled into supercrystals using the same antisolvent crystallization technique. By spatially resolved fluorescence (lifetime) measurements we demonstrate that the optical properties of the supercrystals depend on the specific synthesis conditions of the constituting nanocrystals. Using scanning electron microscopy, small-angle X-ray scattering, and nuclear magnetic resonance spectroscopy, we find evidence that spatial fluctuations in the supercrystal fluorescence correlate with the ligand sphere of the nanocrystals. Specifically, homogeneous surface passivation of the nanocrystals leads to consistent interparticle distances and increased structural order within the supercrystals, resulting in a uniform fluorescence center wavelength and lifetime. The results of this study emphasize the importance of the relationship between crystalline structure and ligand configuration in controlling the optical properties of lead halide perovskite supercrystals.

Transition metal dichalcogenides (TMDCs), including molybdenum disulfide (MoS2), have emerged as a promising candidate for novel semiconducting devices. However, in many cases structural defects significantly affect the electronic properties of the material. The present study utilizes angle-resolved photoelectron spectroscopy (ARPES) and surface-sensitive core-level spectroscopy (SXPS, XAS) with synchrotron radiation to investigate the interfaces between defect-rich MoS2 and perfluorinated cobalt phthalocyanine (CoPcF16). Defects were introduced in synthetic MoS2 bulk crystals by gentle argon and neon sputtering. Although the band structure is still visible after sputtering, especially SXPS reveals structural and electronic disturbances of the topmost MoS2 layer. We show how the Fermi energy in such defect-rich MoS2 can be tuned by the subsequent deposition of CoPcF16, which is verified by a shift in Fermi level for the Ne sputtered surface, under complex charge rearrangements including a charge transfer from all the substrates towards the cobalt atom of the organic molecule.

The reaction of dppb(AuCl)2 and InCl gives the [Au4(dppb)3]2+ cluster where the four gold atoms are arranged in a deltoid. This contrasts all known [Au4]2+ clusters which exclusively form tetrahedral structures. Single crystals of the title compound luminesce with a high quantum yield in the near infrared at room temperature. The excitation wavelength dictates the emission wavelength which ranges from 680 to 918 nm at 77 K. Comprehensive studies of the excitation-dependent emission and luminescence lifetimes in both polycrystalline and single-crystalline samples provide a unique and detailed optical profile of the cluster, uncovering distinct photophysical behavior central to its emissive properties.

We explore the cationic intercalation of tungsten ditelluride (WTe2) with potassium (K), rubidium (Rb), and cesium (Cs), yielding intercalation compounds of the form A0.5WTe2 (A = K, Rb, Cs). Structural characterization was performed using powder X-ray diffraction (PXRD), while diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and temperature-dependent conductivity measurements were employed to investigate the electronic properties. Density functional theory (DFT) calculations were carried out to support the experimental findings and to provide insight into the intercalation mechanisms and the resulting material characteristics. All synthesized compounds display semiconducting behavior with narrow band gaps, emphasizing the influence of alkali metal intercalation on the electronic structure and transport properties of WTe2. These results advance the fundamental understanding of property modulation in transition-metal dichalcogenides (TMDCs) and highlight their potential for electronic device applications.

Colloidal indium antimonide (InSb) quantum dots (QDs) are highly promising nanomaterials for SWIR photodetectors due to their optical properties, solution processability, and low toxicity. Here, we present surface engineering of colloidal InSb QDs and an investigation of the intrinsic and extrinsic photoresponse time (τIn and tEx) of InSb QD photodetectors. Chloride (Cl-) ligands are chosen for surface engineering and their effects are studied by X-ray photoelectron spectroscopy. Using a pump-probe technique based on asynchronous optical sampling (ASOPS), we find that τIn of Cl-capped InSb QDs can be described by two components of 1.5 ns and 200 ps. By studying the dependence of these components on the voltage, the excitation power, and the temperature, we assign them to trap-assisted Auger recombination and carrier trapping. For tEx, we obtain much faster rise times (9.77 µs) than fall times (635 μs), indicating prolonged recovery due to slow release of trapped carriers. We devise measures to partially mitigate this drawback, enabling sub-microsecond photo switching and a 3 dB bandwidth of 5 MHz. Our findings highlight the potential of colloidal InSb QDs for environmentally benign and high-speed SWIR photodetectors.

Colloidal lead mixed-halide perovskite nanocrystals offer exceptional optical properties but suffer from ionic instability and ion migration under external stimuli, challenging their integration into devices. While such effects are well-studied in individual NCs and films, their impact on ordered nanocrystal assemblies remains less understood. Here, we investigate the effect of strong external electric fields on self-assembled CsPbBr3-xClx nanocrystal superlattices. By precisely positioning individual superlattices between micrometre sized capacitor-plates, we analyse field-induced changes in photoluminescence, elemental composition, and morphology. We observe pronounced, spatially dependent PL shifts correlated with halide ion redistribution, as revealed by energy-dispersive X-ray analysis, resulting from non-uniform electric field distribution across the superlattice indicated by finite-element simulations. In-situ mass spectrometry detects bromide sublimation, pointing to a combination of inter- and intra-particle halide diffusion. Irreversible PL changes and morphological distortions further support a field-driven reorganization. These findings show information regarding the structural responses of the CsPbBr3-xClx superlattice, under influence of an external electric field, highlighting the need for improved structural and compositional stability in future optoelectronic applications.

Aryne intermediates in synthetic organic chemistry offer versatile routes to complex heterocyclic structures that are valuable in pharmaceuticals and materials science. We present a one-step aryne-mediated reaction to synthesize pyrido[1,2-a]indoles interconnected through vinylene or 1,2-phenylene linkers to pyridotriazoles using 2-pyridyl-substituted pyridazines and phthalazines as confirmed via single-crystal X-ray crystallography and NMR spectroscopy. This unexpected rearrangement proceeds under mild conditions. Considering that five bonds are broken and three new bonds are formed in the reaction between 3,6-di-2-pyridyl-1,2,4,5-tetrazine and benzyne, the yield of 16% is fair. Electron-rich substituents on aryne precursors destabilized the products, while electron-deficient substituents offered some stability improvements. DFT studies could reveal the mechanism of this rearrangement.