Grazing Incidence Wide-angle X-ray Research Articles

Glutenin phase transition as a method of fabricating primer for superhydrophobic and corrosion-resistant coating

Concerns over food safety arising from conventional plastic and resin-based corrosion barriers cannot be underestimated, particularly in light of the potential for plasticizer migration. We introduce an environmental-friendly and sustainable approach to develop superhydrophobic and anticorrosion coatings. This involved a unique process where glutenin, post-reduction with tris(2-carboxyethyl)phosphine, underwent a phase transition, naturally adhering to diverse surfaces to form a foundational primer. The core mechanism of this adhesion lied the β-sheet stacking configuration, confirmed by grazing-incidence wide-angle X-ray scattering. To further elevate the performance, carnauba wax was easily incorporated as a topcoat, forming a superhydrophobic coating that surpassed standalone wax coatings in durability against wear, impact, high temperature, and corrosion. This enhancement was derived from the intricate intermolecular interactions, including hydrogen bonding and hydrophobic interactions, established between the primer and carnauba wax. Notably, the phase-transited coating and superhydrophobic coating maintained a low-frequency impedance of 0.1 and 2.1 MΩ/cm2, respectively, even after prolonged immersion in a 3.5 % NaCl solution for 21 days. The superhydrophobic coating was ideally applicated in an extensive range of canned food products, such as beverages, fruits, etc., that undergo pasteurization. Additionally, both the primer and the superhydrophobic coating exhibited outstanding biocompatibility, as evidenced by red blood cell hemolysis and cytotoxicity assessments. In summary, this research contributes significant knowledge to the development of superhydrophobic coatings and expand applications of protein-based assembly materials.

Elucidation of the Transformation of Coordination Polymer Intermediates into 2D Metal-Organic Framework Films during Chemical Vapor Deposition.

Chemical vapor deposition (CVD) is a rising tool to synthesize metal-organic framework (MOF) films. Despite growing interest and usage, its mechanism is less known. Especially, the identification of intermediates is crucial for understanding the growth mechanism and further controlling their structures. In this paper, we investigated the growth mechanism of 2D MOF Cu3(C6O6)2 film by CVD. We identified a novel intermediate phase: an octahedral coordination polymer that transforms into an edge-on-oriented 2D MOF. In situ grazing-incidence wide-angle X-ray scattering, X-ray absorption near-edge structure, high-resolution transmission electron microscopy, and Raman spectroscopy studies confirmed that this transformation involves the removal of pillars, leading to the formation of a square-planar 2D MOF. With the identification of intermediates, our study deepens the understanding of MOF film formation by CVD, which lays a foundation to control the structure.

Crystallization dynamics of MAPbI3 perovskite solar cells via solvent engineering methods

Perovskite materials have attracted interest in solar cells due to ease of processing from salts. However, the complex crystal formation of perovskite from solvents is poorly understood. Solvent engineering approach to determine the crystallization dynamics and orientation of MAPbI3 films using grazing incidence wide angle x-ray scattering (GIWAXS) and micro diffraction measurements were studied. The study further probes the effect of moisture, PTAA and PEDOTS: PSS hole transport layers on the stability of MAPbI3 films. Precursor solutions were prepared by dissolving MAI and PbI2 in pure DMF and mixture of DMF: DMSO in 4:1 v/v. Chlorobenzene and Ethyl acetate were used as antisolvent. Films prepared from DMF: DMSO mixture showed no PbI2 signature while those prepared from DMF only, showed PbI2 signature at q= 0.9 A-1. This was attributed to solvent engineering of DMF/DMSO that leads to the formation of MAI/PbI2/DMSO intermediate that delays the crystallization and promotes vertical growth of films. q= 0.9 A-1 signal was associated with high volatility of DMF which led to faster but discrepant nucleation and crystallization rate. Microdiffraction results showed insignificant influence of antisolvent on the perovskite structure. Humidity has a strong influence on the stability of MAPbI3 films. PbI2 intensity in the GIWAXS maps increased with increasing humidity while MAPbI3 intensity decreased. This implied increased degradation of MAPbI3 film with humidity due to recombination of charge carriers. A band gap of 1.57 eV, efficiency of 8.5% and Et of 26 meV were obtained. Films with good crystallization are desirable in solar cells.

Interdependence of Support Wettability - Electrodeposition Rate- Sodium Metal Anode and SEI Microstructure.

This study examines how current collector support chemistry (sodiophilic intermetallic Na2Te vs. sodiophobic baseline Cu) and electrodeposition rate affect microstructure of sodium metal and its solid electrolyte interphase (SEI). Capacity and current (6 mAh cm-2, 0.5-3 mA cm-2) representative of commercially relevant mass loading in anode-free sodium metal battery (AF-SMBs) are analyzed. Synchrotron X-ray nanotomography and grazing-incidence wide-angle X-ray scattering (GIWAXS) are combined with cryogenic ion beam (cryo-FIB) microscopy. Highlighted are major differences in film morphology, internal porosity, and crystallographic preferred orientation e.g. (110) vs. (100) and (211) with support and deposition rate. Within the SEI, sodium fluoride (NaF) is more prevalent with Te-Cu versus sodium hydride (NaH) and sodium hydroxide (NaOH) with baseline Cu. Due to competitive grain growth the preferred orientation of sodium crystallites depends on film thickness. Mesoscale modeling delineates the role of SEI (ionic conductivity, morphology) on electrodeposit growth and onset of electrochemical instability.

Carbon nanotube intermediate layer intercalation and its influence on surface charge of thin film composite membrane

The surface charge of a separation membrane is a critical factor affecting its performance in ion separation and fouling resistance. Thin-film composite (TFC) polyamide (PA) membrane, commonly used in water treatment, often suffer from excessive surface negative charges, which significantly limits their application and fouling resistance. To address this issue, this work introduces a carbon nanotubes (CNT) intermediate layer to adjust the surface charge of TFC PA membranes, aiming to achieve a PA layer with neutral properties. Novel grazing-incidence wide-angle x-ray scattering (GIWAXS) measurements were employed to elucidate the effect of CNT on the molecular chain stacking of PA. The CNT intermediate layer was found to influence the PA cross-linking, which is related to surface negative charge, by controlling the storage and release of the m-phenylenediamine monomer during interfacial polymerization. The neutral CNT-TFC membrane demonstrated improved NH4+ retention and increased resistance to fouling by protein, surfactant, and E. coli. However, other surface properties, such as roughness and hydrophilicity, could counteract the antifouling benefits of a neutral surface. This work provides insights into additional advantages of CNT intermediate layer intercalation in TFC PA membranes, such as enhanced cross-linking and surface charge control.

Determination of molecular arrangement in extremely uniaxial solid thin films of a linear bisazo dye

Abstract The molecular arrangement of the extremely uniaxial thin film was determined using X-ray analysis, including grazing incidence wide-angle X-ray scattering. The highly oriented film was obtained by depositing a bisazo dye onto an aligned polytetrafluoroethylene (PTFE) layer via vacuum evaporation, as shown previously. The X-ray analysis indicated that the molecules are arranged in parallel or antiparallel orientations within the unit cell. Moreover, their long axes are parallel to each other within the grains which are uniformly oriented throughout the film. These results confirm the driving force of the orientation reported previously using a molecular dynamics model: dye molecules trapped along the atomic grooves between adjacent PTFE chains serve as nuclei for crystal growth. In addition, the long molecular axes remain parallel to the rubbing direction, although some grains are inclined in the short-axis direction. This molecular arrangement in the film could contribute to a high degree of uniaxial orientation.

Probing Nanoscale Charge Transport Mechanisms in Quasi-2D Halide Perovskites for Photovoltaic Applications.

Quasi-2D layered halide perovskites (quasi-2DLPs) have emerged as promising materials for photovoltaic (PV) applications owing to their advantageous bandgap for absorbing visible light and the improved stability they enable. Their charge transport mechanism is heavily influenced by the grain orientation of their crystals as well as their nanostructures, such as grain boundaries (GBs) and edge states─the formation of which is inevitable in polycrystalline quasi-2DLP thin films. Despite their importance, the impact of these features on charge transport remains unexplored. In this study, we conduct a detailed investigation on polycrystalline quasi-2DLP thin films and devices, carefully analyzing how grain orientation and nanostructures influence charge transport. Employing nondestructive atomic force microscopy (AFM) topography, along with transient absorption spectroscopy (TAS) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we obtained significant insights regarding the phase purity, crystallographic information, and morphologies of these films. Moreover, our systematic investigation using AFM-based techniques, including Kelvin probe force microscopy (KPFM) and conductive AFM (c-AFM), elucidates the roles played by GBs and edge states in shaping charge transport behavior. In particular, the local band structure along the GBs and edge states within both vertical and parallel grains was found to selectively repel electrons and holes, thus facilitating charge carrier separation. These findings provide perspectives for the development of high-performance quasi-2DLP PV devices and highlight potential approaches that can leverage the intrinsic properties of quasi-2DLPs to advance the performance of perovskite solar cells.

Morphology Optimization by Non-Halogenated and Twisted Volatile Solid Additive for High-Efficiency Organic Solar Cells.

Recently, volatile solid additives have attracted tremendous interest in the field of organic solar cells (OSCs), which can effectively improve device efficiency without sacrificing the reproducibility and stability of the device. However, the structure of reported solid additives is onefold and its working mechanism needs to be further investigated. Herein, a novel non-halogenated and twisted solid additive 1,4-diphenoxybenzene (DPB) is employed to optimize the morphology of the active layer in OSCs. The properties of additive DPB, morphology of active layer, and carrier dynamics behaviors have been systematically investigated through theoretical calculations, in situ and ex situ spectroscopy, grazing-incidence wide-angle X-ray scattering (GIWAXS), and grazing-incidence small-angle X-ray scattering (GISAXS) measurement, as well as ultrafast spectroscopy technology. The results reveal that the twisted additive DPB selectively interacts with acceptor Y6, and thus forms optimized morphology of active layer with increased molecular crystallinity, tight molecular packing, and favorable phase separation. As a result, the optimized devices deliver a remarkable power conversion efficiency (PCE) of 19.04%, which is the highest value for the D18-Cl:N3 system to date. These results demonstrate that non-halogenated and twisted solid additive DPB has broad prospects in the preparation of highly efficient OSCs, providing theoretical and experimental guidance for the development of high-performance solid additives.

Nitrogen-Bridged Fused-Ring Nonacyclic and Heptacyclic A-D-A Acceptors for Organic Photovoltaics.

In this work, we designed two nitrogen-bridged fluorene-based heptacyclic FNT and nonacyclic FNTT ladder-type structures, which were constructed by one-pot palladium-catalyzed Buchwald-Hartwig amination. FNT and FNTT were further end-capped by FIC acceptors to form two FNT-FIC and FNTT-FIC non-fullerene acceptors (NFAs), respectively. The two NFAs exhibit more red-shifted absorption and higher crystallinity compared to those of the corresponding carbon-bridged FCT-FIC and FCTT-FIC counterparts. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements reveal that the 2-butyloctyl groups on the nitrogen in the convex region of FNT-FIC interdigitate with the dioctyl groups on the fluorene in the concave region of another FNT-FIC, resulting in a lamellar packing structure with a d spacing of 13.27 Å. As a consequence, the PM6:FNT-FIC (1:1 wt %) device achieved a power conversion efficiency (PCE) of only 6.60%, primarily due to the highly crystalline nature of FNT-FIC, which induced significant phase separation between PM6 and FNT-FIC in the blended film. However, FNTT-FIC, featuring 2-butyloctyl groups positioned on the nitrogen within the concave region of its curved skeleton, exhibits improved donor-acceptor miscibility, thereby promoting a more favorable morphology. As a result, the PM6:FNTT-FIC (1:1.2 wt %) device exhibited a higher PCE of 12.15% with an exceptional Voc of 0.96 V. This research demonstrates that placing alkylamino moieties within the concave region of curved A-D-A NFAs leads to a better molecular design.

Successively Controlling Nanoscale Wrinkles of Ultrathin 2D Metal-Organic Frameworks Nanosheets.

The wrinkles are pervasive in ultrathin two-dimensional (2D) materials, but the regulation of wrinkles is rarely explored systematically. Here, we employed a series of carboxylic acids (from formic acid to octanoic acid) to control the wrinkles of Zr-BTB (BTB=1, 3, 5-(4-carboxylphenyl)-benzene) metal-organic framework (MOF) nanosheet. The wrinkles at the micrometer scale were observed with transmission electron microscopy. Furthermore, high-angle annular dark-field (HAADF) images showed lattice distortion in many nanoscale regions, which was precisely matched to the nano-wrinkles. With the changes of hydrophilicity/hydrophobicity, MOF-MOF and MOF-solvent interactions were possibly synergistically regulated and wrinkles with different sizes were obtained, which was supported by HAADF, molecular dynamics, and density functional theory calculation. Different wrinkle sizes resulted in different pore sizes between the Zr-BTB nanosheet interlayers, providing highly-oriented thin films and the successive optimization of kinetic diffusion pathways, proved by grazing-incidence wide-angle X-ray scattering and nitrogen adsorption. The most suitable wrinkle pore from Zr-BTB-C4 exhibited highly efficient chromatographic separation of the substituted benzene isomers. Our work provides a rational route for the modulation of nanoscale wrinkles and their stacked pores of MOF nanosheets and improves the separation abilities of MOFs.

Sputter-deposited TiOx thin film as a buried interface modification layer for efficient and stable perovskite solar cells

Despite perovskite solar cells (PSCs) based on a SnO2 hole-blocking layer (HBL) are achieving excellent performance, the non-perfect buried interface between the SnO2 HBL and the perovskite layer is still an obstacle in achieving further improvement in power conversion efficiency (PCE) and stability. The poor morphology with numerous defects and the energy level mismatch at the buried interface constrain the open circuit voltage and cause instability. Herein, a sputter-deposited TiOx thin film is used as a buried interface modification layer to address the aforementioned issues. Utilizing in situ grazing-incidence small-angle X-ray scattering (GISAXS) during the sputter deposition, we monitor and unveil the growth process of the TiOx thin film, identifying a 10 nm thickness optimum. The defects at the buried interface are passivated through tuning the growth, leading to a suppressed non-radiative recombination and improved PCE (from 22.19 % to 23.93 %). The evolution of the device performance and the degradation process of PSCs using operando grazing-incidence wide-angle X-ray scattering (GIWAXS) under the protocol ISOS-L-1I explains the enhanced stability introduced by the buried interface modification via a sputter-deposited TiOx thin layer. The perovskite decomposition process and the detrimental formation of PbI2 are both slowed down by the TiOx thin layer.

Correlation of Processing and Structure in an Ethylene-Glycol Side-Chain Modified Polythiophene via Combined X-Ray Scattering and 4D Scanning Transmission Electron Microscopy.

The results of a combined grazing incidence wide-angle X-ray scattering (GIWAXS) and 4D scanning transmission microscopy (4D-STEM) analysis of the effects of thermal processing on poly(3[2-(2-methoxyethoxy)ethoxy]-methylthiophene-2,5-diyl) are reported, a conjugated semiconducting polymer used as the active layer in organic electrochemical transistor devices. GIWAXS provides a measure of overall crystallinity in the film, while 4D-STEM produces real-space maps of the morphology and orientation of individual crystallites along with their spatial extent and distribution. The sensitivity of the 4D-STEM detector allows for collection of electron diffraction patterns at each position in an image scan while limiting the imparted electron dose to below the damage threshold. The effects of heat treatment on the distribution and type of crystallites present in the films isdetermined.

Energy Level Tuning in Conjugated Donor Polymers by Chalcogen Exchange for Low Dark Current Organic Photodetectors.

The performance of organic photodetectors (OPDs) using conjugated polymer donors and molecular acceptors has improved rapidly, but many polymers are difficult to upscale due to their complex structures. This study examines two low-complexity thiophene copolymers with substituted benzooxadiazole (FO6-BO-T) or benzothiadiazole (FO6-T). Substituting sulfur with oxygen in FO6-BO-T increased its ionization energy without affecting the optical gap. When blended with the nonfullerene acceptor IDSe, FO6-BO-T showed a significantly lower dark current density (2.06·10-9 A cm-2 at -2 V) compared to FO6-T. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements demonstrated that pristine FO6-BO-T exhibited a more ordered morphology than FO6-T. However, blending resulted in a significant disruption to the ordered domains in both cases, with a loss of orientational order, suggesting that FO6-BO-T's improved performance is largely related to its increased ionization energy. This study demonstrates the potential of chalcogen atom engineering to enhance the performance of the OPD in scalable polymers.

Stepwise Crystallization and Mass Transport Limitations in Annealed SPEEK Thin Films

Pt-supported SPEEK (sulfonated poly ether ether ketone) thin films, mimicking the ionomer-electrode interface in polymer electrolyte fuel cells (PEFCs), were synthesized with thicknesses from 12 to 105 nm. Their glass transition temperature (Tg) was analyzed via in-situ thermal ellipsometry, revealing a thickness-dependent Tg decrease, indicative of confinement effects. Particularly, a 30 nm film, typical of practical ionomer films, exhibited surface crystallization preceding that at the buried interface, a phenomenon linked to higher mobility at the free surface, as con-firmed by grazing incidence wide-angle X-ray scattering (GI-WAXS) at both sub-critical (0.09º) and supercritical (0.14º) angles. This study elucidates the dynamic interplay between the high-mobility free surface and the interaction-intensive buried interface in confined SPEEK thin films. It was observed that below 30 nm thickness, interfacial interactions become the primary factor influencing transition temperature. Additionally, spatially heterogeneous crystallization, more pronounced in the out-of-plane direction, correlates with reduced proton conduction.

2D Phase Formation on 3D Perovskite: Insights from Molecular Stiffness.

Several studies have demonstrated that low-dimensional structures (e.g., two-dimensional (2D)) associated with three-dimensional (3D) perovskite films enhance the efficiency and stability of perovskite solar cells. Here, we aim to track the formation sites of the 2D phase on top of the 3D perovskite and to establish correlations between molecular stiffness and steric hindrance of the organic cations and their influence on the formation and crystallization of 2D/3D. Using cathodoluminescence combined with a scanning electron microscopy technique, we verified that the formation of the 2D phase occurs preferentially on the grain boundaries of the 3D perovskite. This helps explain some passivation mechanisms conferred by the 2D phase on 3D perovskite films. Furthermore, by employing in situ grazing-incidence wide-angle X-ray scattering, we monitored the formation and crystallization of the 2D/3D perovskite using three cations with varying molecular stiffness. In this series of molecules, the formation and crystallization of the 2D phase are found to be dependent on both steric hindrance around the ammonium group and molecular stiffness. Finally, we employed a 2D/3D perovskite heterointerface in a solar cell. The presence of the 2D phase, particularly those formed from flexible cations, resulted in a maximum power conversion efficiency of 21.5%. This study provides insight into critical aspects related to how bulky organic cations' stiffness and steric hindrance influence the formation, crystallization, and distribution of 2D perovskite phases.

GdWN3 is a nitride perovskite

Nitride perovskites ABN3 are an emerging and highly underexplored class of materials that are of interest due to their intriguing calculated ferroelectric, optoelectronic, and other functional properties. Incorporating novel A-site cations is one strategy to tune and expand such properties; for example, Gd3+ is compelling due to its large magnetic moment, potentially leading to multiferroic behavior. However, the theoretically predicted ground state of GdWN3 was a non-perovskite monoclinic structure. Here, we experimentally show that GdWN3−y crystallizes in a perovskite structure. High-throughput combinatorial sputtering with activated nitrogen is employed to synthesize thin films of Gd2−xWxN3−yOy with oxygen content y < 0.05. Ex situ annealing crystallizes a polycrystalline perovskite phase in a narrow composition window near x = 1. LeBail fits of synchrotron grazing incidence wide angle x-ray scattering data are consistent with a perovskite ground-state structure. Refined density functional theory calculations that included antiferromagnetic configurations confirm that the ground-state structure of GdWN3 is a distorted Pnma perovskite with antiferromagnetic ordering, in contrast to prior predictions. Initial property measurements find that GdWN3−y is paramagnetic down to T = 2 K with antiferromagnetic correlations and that the absorption onset depends on cation stoichiometry. This work provides an important path toward both the rapid expansion of the emerging family of nitride perovskites and understanding their potential multiferroic properties.

Synchrotron Radiation-Based In Situ GIWAXS for Metal Halide Perovskite Solution Spin-Coating Fabrication.

Solution-processable perovskite-based devices are potentially very interesting because of their relatively cheap fabrication cost but outstanding optoelectronic performance. However, the solution spin-coating process involves complicated processes, including perovskite solution droplets, nucleation of perovskite, and formation of intermediate perovskite films, resulting in complicated crystallization pathways for perovskite films under annealing. Understanding and therefore controlling the fabrication process of perovskites is difficult. Recently, synchrotron radiation-based in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) techniques, which possess the advantages of high collimation, high resolution, and high brightness, have enabled to bridge complicated perovskite structure information with device performance by revealing the real-time crystallization pathways of perovskites during the spin-coating process. Herein, the developments of synchrotron radiation-based in situ GIWAXS are discussed in the study of the crystallization process of perovskites, especially revealing the important crystallization mechanisms of state-of-the-art perovskite optoelectronic devices with high performance. At the end, several potential applications and challenges associated with in situ GIWAXS techniques for perovskite-based devices are highlighted.

In Situ Annealing Effect on Thermally Co-Evaporated CsPbI2Br Thin Films Studied via Spectroscopic Ellipsometry.

All-inorganic cesium lead halide perovskites possess excellent thermal stability, a feature that renders them highly favorable for optoelectronic applications with an elevated thermal budget. Employing a coevaporation approach for their deposition holds promise for manufacturing at an industrial level, owing to improvements in device scalability and reproducibility. For unlocking the full potential of vacuum-evaporated perovskite thin films, it is crucial to delve deeper into their crystallization process, which, as a solid-state reaction, has been less investigated compared to the crystallization process of, most commonly used, solution-based methods. In this work, we employ spectroscopic ellipsometry, a nondestructive, high speed, and high accuracy characterization method, to study the real time annealing effect on thermally coevaporated CsPbI2Br thin films in a temperature range between 25 and 300 °C. We achieve this by developing a singular dynamic model that can be fitted in real time as a function of temperature, providing insights into how thermal annealing influences the perovskite film's morphology and optical constants. Based on the latter, we derive the temperature dependence of the thermo-optic coefficient and Urbach energy as well as analyze the interband transition energies via critical point analysis. We demonstrate that the γ- to β-phase transition can be identified through a pronounced shift in the bandgap energy, whereas the β- to α-phase transition can be discerned by a sharp increase in the film's roughness. We corroborate the obtained fit results with additional in- and ex situ measurements, such as in situ grazing incidence wide-angle X-ray scattering, atomic force microscopy, reflectance/transmittance, and profilometry.

Real-Time Monitoring of Electrochemical Reactions in All-Solid-State Lithium Batteries by Simultaneous Grazing-Incidence Small-Angle/Wide-Angle X-Ray Scattering

Polyethylene oxide (PEO)-based composite electrolytes (PCEs) are considered as the promising candidates for next generation lithium metal batteries due to its high safety, easy fabrication and good electrochemical stability. However, the material suffers from low conductivity and high crystallinity of the ethylene oxide (EO) chain, which inhibits its commercialization. Therefore, it is crucial to understand the electrochemcial process as well as Li+ transfer pathway within PEO-based batteries. Using operando grazing-incidence small-angle and wide-angle X-ray scattering (GISAXS and GIWAXS) in Li||Cu cell framework, we find that the electrochemical reaction within the PCE is highly correlated with the evolution of the buried morphology and crystalline structure evolution of the PCE. This two irreversible reactions, PEO-Li+ reduction and TFSI- decomposition, cause changes in both the crystalline structure and morphology of the PCE. In addition, the reversible Li plating/stripping process alters the inner morphology, especially the PEO-LiTFSI domain radius, rather than causing crystalline structure changes. This work provides a new path to monitor a working battery in real time, thereby enabling detailed understanding of electrochemically-induced changes of the microscopic morphology and crystalline structure of PCE, which is essential for developing high transferable and interface stable PCE-based lithium metal batteries. Figure 1

(Invited) In Situ and Operando Scattering Studies on Quantum Dot-Based Devices

Colloidal quantum dots (QDs) made e.g. of PbS are attractive for various optoelectronic applications due to their tunable band gap with a large absorption wavelength range from the visible to the near-infrared region. Moreover, due to the high intrinsic permittivity, the exciton binding energy of PbS is smaller than in cadmium chalcogenide QDs and polymer materials, which is beneficial for devices driven by charge carrier generation and transport, e.g. photovoltaics and photodetectors.In this work, we introduce wet chemical deposition methods beyond spin coating such as printing and spray deposition of QDs as a facile and potentially large-scale deposition method for high-performance photodetectors. The inner structures including the inter-dot distance of neighboring QDs and the structure, in the deposited QD solids, are studied by grazing-incidence small-angle X-ray scattering (GISAXS). In addition, the facet orientation of the QDs in the QD solids is characterized by grazing-incidence wide-angle X-ray scattering (GIWAXS). In particular, in situ GISAXS/GIWAXS studies during film formation are able to provide detailed information about the complex kinetic processes [1,2]. Operando GISAXS/GIWAXS studies on QD-based devices such as solar cells bring an in-depth understanding of the degradation mechanisms, which is key for improving the device stability and thereby bringing these novel materials into real-world applications [3]. Superlattice deformation in QD films on flexible substrates via uniaxial strain is followed in situ with GISAXS, providing a fundamental understanding of the impact of strain on the performance of flexible devices based on QD films, such as wearable electronics and next-generation solar cells on flexible substrates [4]. Nanoscale Horiz. 5, 880-885 (2020)Nano Energy 78, 105254 (2020)Energy Environ. Sci. 14, 3420-3429 (2021)Mater. Horizon 8, 383-395 (2023)