Advanced Materials

The cover image depicts the direct writing of a germanium nanostructure with the tip of an atomic force microscope (AFM). Germanium writing occurs when the AFM tip traces the desired shape along a biased silicon sample while immersed in an organometallic precursor (diphenylgermane). The high-electric field and the electrons emitted from the tip cause the precursor to locally react and yield germanium nanostructures. This innovative AFM strategy creates sub-30 nm carbon-free germanium nanostructures with desired geometries and placement, as reported on p. 4639 by Marco Rolandi and co-workers.

Self-wound nanomembranes from functional multilayered structures can improve lithium storage performance report Yongfeng Mei and co-workers on p. 4591. Intrinsic strain is relaxed by rolling; the composite components are uniformly dispersed; the micro/nanohierarchical structure assumes a mixed ion/electron conduction network; and the conventional nanomembrane deposition techniques allow for various materials combinations, making the technique suitable for meeting different demands in lithium ion batteries.

Historical scientific books describe a wealth of organisms which could be useful to materials scientists in search of “bio-inspiration”. Very often these books are not written in English, and are not easy for the materials science community to access. We propose that translating and re-editing such books or making them available electronically could be of extreme value to present-day researchers. (Side view of a diatom with a siliceous skeleton drawn by Häckel in 1904, reproduced with permission from Marixverlag GmbH, Wiesbaden.)

Progress in using biomimetic nanopatterns for cell biological applications has been rapidly accelerating. Here, bio-nanopatterning methods and their applications as enabling tools for analysis and control of live cells are extensively discussed. This review also highlights the impact of nanoscale engineering in controlling cell-material interfaces, with profound implications for future developments in tissue engineering and regenerative medicine.

Hyperbranched polymers have demonstrated great potential as excellent precursors in supramolecular self-assembly, and many delicate supramolecular structures from zero-dimension to three-dimension have been prepared, such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and so on. They have displayed promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry.

Self-wound nanomembranes out of functional multilayered structures were designed to improve lithium storage performance. The intrinsic strain is relaxed by rolling; the composite components are uniformly dispersed; the micro/nanohierarchical structure assumes a mixed ion/electron conduction network; and conventional nanomembrane deposition techniques allow for various materials combinations, suitable to meet different demands of lithium ion batteries.

Doping ease and the ability to readily nanoimprint silk films offer the possibility to rapidly prototype photonic devices that couple optical functions with embedded material properties. By imprinting fluorescent silk films with periodic nanoscale lattices matched to the emission spectra of the doping fluorophores it is possible to selectively enhance the emission from the film.

Multicomponent and robust structures of quantum dots, in the form of stripes and grids, are produced by a simple flow coating method giving unprecedented control over macroscopic architectures from nanoscopic components. Crosslinking and lift-off of stripes lead to free-floating structures of nanoparticles that are flexible, robust, and fluorescent.

Near atomically smooth, void-free, centimeter-long amorphous silicon waveguides are produced by high pressure chemical fluid deposition in the pores of a microstructured optical fiber template (right inset). Semiconductor waveguides fabricated by conventional deposition/fabrication approaches have a surface roughness that is a constraining factor in most optoelectronic devices, but these waveguides conform to the extraordinarily geometrically perfect optical fiber pores (DIC image, bottom inset).

We present an approach to inkjet print high-performance organic transistors by printing the organic semiconductor ink on a thin, continuous, and solvent-absorbing layer of insulating material. The ink spreading is effectively controlled by local dissolution of the layer, and during drying the characteristic circular morphology with high rims and inner plateau forms.

A narrow bandgap, strong donor-acceptor polymer semiconductor is presented. This “transistor paint” material exhibits hole mobilities as high as 0.41 cm²/Vs. Importantly, the semiconductor yields high reproducible mobility values of 0.28 cm²/Vs ± 0.019 for a range of channel lengths when measured from several transistors on different days.

The success of the patch-clamp technique has driven an effort to create wafer-based patch-clamp platforms. We develop a lithographic/electrochemical processing scheme that generates ultrasmooth, high aspect ratio pores in quartz. These devices achieve gigaohm seals in nearly 80% of trials, with the majority exhibiting seal resistances from 20-80 GΩ, competing with pipette-based patch-clamp measurements.

Nanometer-sized hydrides are attractive for hydrogen storage. Nanofabricated model systems can be studied by a novel localized surface plasmon resonance (LSPR) based direct sensing approach and by quartz crystal microbalance. The role of nanoparticle size, shape and microstructure on the storage thermodynamics can be scrutinized.

A single step process to fabricate arrays of organic LEDs with emission colors across the entire visible spectrum is introduced (see picture). This multi-color monolithic integration of OLEDs is enabled by a grayscale lithography scheme that inscribes thickness profiles into crosslinkable hole-transport layers. When introduced into a micro-cavity OLED, these thickness variations translate into shifts of the resonant wavelength of the cavity.

Atomic force direct-write of carbon-free germanium nanostructures is easily accomplished via high-field reaction of liquid diphenylgermane precursor. Sub-30 nm features are written in arbitrary patterns at velocities as high as 100 μm s⁻¹.

A multiscale method that allows a noninvasive and precise integration of thousands of nano- or microscale electronic devices into large macroscopic materials or structures of any 3D shape and rigidity is demonstrated. An array of microsensors (for strain and temperature) is built on a spider-web-like, highly expandable and flexible polyimide substrate that is engineered in such a way as to allow unique area dilatations.

A split-gate field effect transistor containing four electrodes, source, drain, two gates allows enhanced transport for specific carrier species and separate control of carrier polarity over two gate regimes. The device can be operated as a transistor or a diode by controlling gate biases.