Preparation of Phospholipid Multilayer Patterns of Controlled Size and Thickness by Capillary Assembly on a Microstructured Substrate

By dragging a phospholipid solution on microstructured silicon surfaces, phospholipid molecules are selectively deposited inside the microstructures to get regular phospholipid multilayer patterns of controlled thickness over a large scale (～cm²). By varying the dragging speed, the thickness of the patterns varies between 28 and 100 nm on average (7 to 25 bilayers). Electroswelling of phospholipid multilayer patterns leads to the formation of giant liposomes of controlled size and narrow size distributions.     

One‐Step Fabrication of Pillar and Crater‐Like Structures on Titanium Using Direct Laser Interference Patterning

Direct laser interference patterning (DLIP) is used to create periodic crater‐ and pillar‐like patterns on titanium surfaces. A Nd:YAG laser operating at 532 nm wavelength with a pulse duration of 8 ns and the ability to control the polarization of each individual beam is used for the laser patterning process. The generated periodic patterns with spatial periods of 5 and 10 μm are produced with energy densities between 0.3 and 5.1 J cm^?2 with a single laser pulse. By varying the polarization of each interfering beam and the energy density, various forms of the occurring topography are observed due to the different shape of the interference intensity pattern and the solidification front of the molten material at the maxima positions. The characterization of the surface chemistry shows that the laser treatment increases the relative content of alumina in the reactive layer from 36% to 51%. The structural analysis of pillar‐like patterned surface shows no changes in microstructure after the laser treatment. Contact angles of 47° ± 7° down to 6° ± 4° are measured on both, crater‐ and pillar‐like surfaces which are significantly lower compared to the untreated reference (79° ± 2°).

     

Surface Modification of Fluorine-Doped Tin Oxide Thin Films Using Femtosecond Direct Laser Interference Patterning: A Study of the Optoelectronic Performance

Transparent conductive oxides (TCOs) are used in solar cells not only to extract photogenerated carriers but also to allow sunlight to reach the photoactive material. Therefore, controlling the electrical and optical properties of such oxides is crucial for the optimization of the efficiency of solar cells. Herein, direct laser interference patterning (DLIP) method is used to control the surface morphology, optical and electrical properties of fluorine-doped tin oxide (FTO) by applying femtosecond laser pulses. The topography characterization reveals periodic line-like microstructures with a period of 3.0 μm and average heights between 20 and 185 nm, depending on the applied laser fluence levels. Laser-induced periodic surface structures are observed on the valleys of the texture aligned perpendicularly to the laser radiation polarization. A relative increase in the average total and diffuse optical transmittance up to 5% and 500%, respectively, is obtained in the 400–800 nm spectral range as a consequence of the generated micro- and nanostructures. Calculations of two figures of merit suggest that the texturing of FTO might enhance the efficiency of solar cells, in particular dye-sensitized (DSSCs). The findings of this study confirm that DLIP is a convenient technique for structuring electrodes for highly efficient optoelectronic devices.     

Atomic‐Level Sculpting of Crystalline Oxides: Toward Bulk Nanofabrication with Single Atomic Plane Precision

The atomic‐level sculpting of 3D crystalline oxide nanostructures from metastable amorphous films in a scanning transmission electron microscope (STEM) is demonstrated. Strontium titanate nanostructures grow epitaxially from the crystalline substrate following the beam path. This method can be used for fabricating crystalline structures as small as 1–2 nm and the process can be observed in situ with atomic resolution. The fabrication of arbitrary shape structures via control of the position and scan speed of the electron beam is further demonstrated. Combined with broad availability of the atomic resolved electron microscopy platforms, these observations suggest the feasibility of large scale implementation of bulk atomic‐level fabrication as a new enabling tool of nanoscience and technology, providing a bottom‐up, atomic‐level complement to 3D printing.     

Inside Front Cover: A Combined Top‐Down/Bottom‐Up Approach for the Nanoscale Patterning of Spin‐Crossover Coordination Polymers (Adv. Mater. 16/2007)

The background scanning electron microscopy image shows nanometric patterns of the 3D spin crossover coordination polymer Fe(pyrazine)[Pt(CN)₄] (see schematic structure in the circle), which have been fabricated using a combination of lift‐off and multilayer sequential assembly methods. These patterns, reported by Gábor Molnár, Azzedine Bousseksou, and co‐workers on p. 2163, exhibit a bistability of their electronic states (¹A₁ ? ⁵T₂), and thus represent a novel platform for a wide array of potential applications.