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Morphology Phase Diagram of Slot‐Die Printed TiO <sub/>2</sub> Films Based on Sol–Gel Synthesis
摘要： Mesoporous titania films with tailored nanostructures are fabricated via slot-die printing, which is a simple and cost-effective thin-film deposition technique with the possibility of a large-scale manufacturing. Based on this technique, which is favorable in industry, TiO2 films possess the similar advantage with polymer semiconducting devices like ease of large-scale production. The titania morphologies, including foam-like nanostructures, nanowire aggregates, collapsed vesicles and nanogranules, are achieved via a so-called block-copolymer-assisted sol–gel synthesis. By adjusting the weight fraction of reactants, the ternary morphology phase diagram of the printed titania films is probed after template removal. The surface and inner morphology evolutions are explored with scanning electron microscopy and grazing incidence small-angle X-ray scattering, respectively. Special focus is set on foam-like titania nanostructures as they are of especial interest for, e.g., solar cell applications. At a low weight fraction of the titania precursor titanium(IV)isopropoxide (TTIP), foam-like titania films are achieved, which exhibit a high uniformity and possess large pore sizes. The anatase phase of the highly crystalline titania films is verified with X-ray diffraction and transmission electron microscopy.
关键词： TiO2 films,crystallinity,morphology phase diagram,printing,GISAXS
更新于2025-11-21 11:20:42
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In Situ Study of Sputtering Nanometer-Thick Gold Films onto 100 Nanometer-Thick Spiro-OMeTAD Films: Implications for Perovskite Solar Cells
摘要： The performance of many perovskite solar cells is closely related to the spiro-OMeTAD/gold interface since gold is used as top contacts, which renders the detailed understanding of the interface formation very important. In this work, sputter deposition as an industry-relevant, high-rate, large-scale and well-controllable deposition technique is used to prepare gold electrodes on top of a 100 nm thick spiro-OMeTAD film. In situ grazing incidence small angle X-ray scattering (GISAXS) is used to study the nanostructure-growth kinetics of the gold contact on top of the spiro-OMeTAD film during the sputter process. The results show that the gold grows in nanoscale clusters, which then coalesce into a complete yet still nanogranular layer forming the top contact with a thickness of 90 nm. Based on simulations of the 2D GISAXS patterns additional information about the shape of the nanosized gold cluster is gained at the different cluster growth stages. Furthermore, the diffusion of gold into the spiro-OMeTAD film occurs during the sputter process as verified with X-ray reflectivity. In a depth of 3.5 nm below the gold contact the gold doping level of the spiro-OMeTAD film is 6.3 % irrespective of the final gold contact thickness. Thus, the interface between the spiro-OMeTAD film and the Au contact is not sharp as commonly sketched as well as the contact is grainy, which will be both of importance for the performance of device such as perovskite solar cells.
关键词： gold contacts,spiro-OMeTAD film,sputter deposition,in situ GISAXS,growth kinetics
更新于2025-09-23 15:21:01
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The coupled dynamics of colloidal nanoparticle spreading and self-assembly at a fluid-fluid interface
摘要： We investigated the physicochemical and transport phenomena governing the self-assembly of colloidal nanoparticles at the interface of two immiscible fluids. By combining in-situ grazing incidence small-angle X-ray scattering (GISAXS) with a temporal resolution of 200 ms and electron microscopy measurements we gained new insights into the coupled effects of solvent spreading, nanoparticle assembly and recession of the vapor-liquid interface on the morphology of the self-assembled thin films. We focus on oleate-passivated PbSe nanoparticles dispersed across an ethylene glycol subphase as a model system and demonstrate how solvent parameters such as surface tension, nanoparticle solubility, aromaticity and polarity influence the mesoscale morphology of the nanoparticle superlattice. We discovered that a nanoparticle precursor monolayer film spreads in front of the bulk solution and influences the fluid spreading across the subphase. Improved understanding of the impact of kinetic phenomena (i.e., solvent spreading and evaporation) on superlattice morphology is important to describe the formation mechanism and ultimately enable assembly of high-quality superlattices with long range order.
关键词： self-assembly,interfacial phenomena,in-situ GISAXS,nanoparticle superlattice,spreading dynamics
更新于2025-09-23 15:21:01
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Binary Superlattices of Infrared Plasmonic and Excitonic Nanocrystals
摘要： Self-assembled superlattices of nanocrystals offer exceptional control over the coupling between nanocrystals, similar to how solid-state crystals tailor the bonding between atoms. By assembling nanocrystals of different properties (e.g., plasmonic, excitonic, dielectric, or magnetic), we can form a wealth of binary superlattice metamaterials with new functionalities. Here, we introduce infrared plasmonic Cu2?xS nanocrystals to the limited library of materials that have been successfully incorporated into binary superlattices. We are the first to create a variety of binary superlattices with large excitonic (PbS) nanocrystals and small plasmonic (Cu2?xS) nanocrystals, both resonant in the infrared. Then, by controlling the surface chemistry of large Cu2?xS nanocrystals, we produced structurally analogous superlattices of large Cu2?xS and small PbS nanocrystals. Transmission electron microscopy (TEM) and grazing-incidence small-angle X-ray scattering (GISAXS) were used to characterize both types of superlattices. Furthermore, our unique surface modification of the large Cu2?xS nanocrystals also prevented them from chemically quenching the photoluminescence of the PbS nanocrystals, which occurred when the PbS nanocrystals were mixed with unmodified Cu2?xS nanocrystals. These synthetic achievements create a set of binary superlattices that can be used to understand how infrared plasmonic and excitonic nanocrystals couple in a variety of symmetries and stoichiometries.
关键词： infrared quantum dots,nanocrystals,self-assembly,supracrystal,metamaterial,binary superlattice,grazing-incidence small-angle X-ray scattering (GISAXS)
更新于2025-09-23 15:21:01
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Stress Evolution during Ge Nanoparticles Growth in a SiO <sub/>2</sub> Matrix
摘要： Superstructures are explored that were obtained by multilayer magnetron deposition at room temperature of 20 SiO2 and SiO2:Ge bilayers, each 2 × 4 nm thick, and subsequently annealed in inert N2 atmosphere at different temperatures in the range of 500?750 °C. The structural and optical changes induced by annealing and the formation and growth of Ge nanoparticles (nps) from early clusters to their full growth and final dissolution were studied by the simultaneous grazing-incidence small- and wide-angle X-ray scattering, transmission electron microscopy, and (time-resolved) photoluminescence (PL). It is shown that in as-deposited multilayers aggregation of small clusters already occurred, and the clusters were reasonably well intercorrelated in the lateral plane. During annealing at Ta = 550 °C or higher temperatures, Ge nps start to form and remain partly amorphous at lower Ta but crystallize completely at about 600 °C. At even higher temperatures, the Ge nps dissolve and Ge diffuses out almost completely, leaving voids in the SiO2 matrix. Visible PL from the samples was detected and attributed to defects in the nps/matrix interface layers rather than to the nps itself because PL persisted even after Ge nps dissolution.
关键词： GIWAXS,photoluminescence,Ge nanoparticles,GISAXS,stress evolution,SiO2 matrix,TEM
更新于2025-09-11 14:15:04
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Rapid and sheet-to-sheet slot-die coating manufacture of highly efficient perovskite solar cells processed under ambient air
摘要： A nitrogen-free and slot-die coating fabrication of perovskite solar cells combined with NIR annealing. We develop a fabrication approach of planar inverted structured perovskite solar cell (PSC) in ambient condition with a PCE of 12.4% as compared to that (13.3%) of PSC fabricated in glove box filled with nitrogen. In addition, we demonstrate an alternative post-annealed method by near-infrared (NIR) radiation to traditional heating method by oven. The annealed time by NIR can be shortened from 1500 s to 30 s and the device performance over 10% can be achieved. The present work investigates the NIR effect for different layers in the two-step processing on the cell performance. The grazing-incidence wide-angle and small-angle X-ray scattering (GIWAXS and GISAXS) techniques for the perovskite layers are performed to reveal the crystalline and nano-morphological structures of perovskite layers correlated to thermal and NIR annealing effects. Based on this approach under ambient air, we scale up to the large-area fabrication using the slot-die coating. The performance of slot-die coated PSC can achieve to 12.3%. The critical step is the control of PbI2 layer thickness. We also applied the NIR radiation to the slot-die coated PSC and the PCE of 11.4% can be achieved. Our study paves a facile way to rapid manufacture and mass production of perovskite solar cells.
关键词： Perovskite solar cell,Two-steps,Near-infrared radiation,Slot-die,GIWAXS,GISAXS
更新于2025-09-09 09:28:46
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[IEEE 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Bento Gon?alves, Brazil (2018.8.27-2018.8.31)] 2018 33rd Symposium on Microelectronics Technology and Devices (SBMicro) - Characterization by GISAXS and Electrochemical Impedance Spectroscopy of porous oxide films
摘要： Porous oxide films were deposited by reactive sputtering. Some films received UV cures and/or a Si cap. The FTIR analyses show that the deposited films were very hydrophilic. Standard ellipsometric porosimetry was not able to determine porosity nor pore size. With GISAXS, the porosity of different films was determined (approximately 13%) and the (mostly spherical pores with a radius of approximately 5 nm). Electrochemical Impedance Spectroscopy completed the pore analysis, indicating mostly open porosity. These techniques were sufficiently sensitive to show that the Si cap closed the pores somewhat while the UV cure increased the porosity.
关键词： porous oxide,electrochemical impedance spectroscopy,GISAXS
更新于2025-09-09 09:28:46