MMaterialsgateNEWS vom 11.09.2009

Thermochemical nanopatterning of organic semiconductors

Researchers from the London Centre for Nanotechnology (LCN) and University College London (UCL) have fabricated sub-30 nm luminescent features of an organic semiconductor ...

via spatially selective conversion and patterning of its precursor by using a heatable, micron-size scanning probe (see figure below). The results will soon be reported in the journal Nature Nanotechnology.

The future development of electronics and photonics relies on a range of sophisticated lithographyic techniques for the patterning of semiconducting, dielectric, and metallic materials. Researchers at the London Centre of Nanotechnology (LCN), the Department of Physics and Astronomy, and the Eastman Dental Institute at UCL, have now developed a thermochemical patterning technique for materials known as organic semiconductors.

These materials can be used in light-emitting diodes (LEDs), solar cells, lasers and transistors, and their potential is in low processing costs and the ability to build devices on flexible substrates. However, applications of these materials in nanoelectronics and nanophotonics are limited by the range of patterning techniques available. Many of the approaches to nanolithography that are used to pattern inorganic materials, such as e-beams or Focused Ion Beams (FIBs), are too harsh for organic semiconductors, that can be damaged by the high energy of the patterning beams, or by the chemicals needed for the processing.

So, instead of using standard optical or other “conventional” high-resolution lithographies, the UCL researchers used a small heat source for the patterning. This heat source, known as a modified Wollaston wire, can be mounted on an atomic force microscope and scanned across surfaces to chemically convert all areas it comes into contact with. This technique has allowed the UCL researchers to achieve patterned resolutions below 28 nm and write speeds of 100 µm/s in the widely used organic semiconductor, PPV. The result is particularly surprising given the large diameter of the heat source (5 µm) compared to the resolutions achieved, and since it is likely that resolution could be further improved with the use of nanoscale heat sources, as already reported by other groups.

There has already been some commercial interest in using atomic force microscopes to pattern surfaces, as for example by IBM in their ‘millipede’ project, that was aimed at data-storage applications, but such a thermochemical approach opens up new possibilities. In particular, this work shows that thermochemical lithography offers a versatile, simple and reliable nanopatterning technique. For example, thermo-crosslinkable additives could easily be added to a variety of other solution-processible semiconductors. The technique should also be generally applicable to other classes of materials. A large number of optical materials, including many commercial cross-linker additives and photoresists, rely in fact on chemical mechanisms that can also be thermally activated.

The group, led by Franco Cacialli, has previously used scanning near-field optical lithography (SNOL) for nanopatterning of PPV structures from the same precursor polymer, poly(p-xylene tetrahydrothiophenium chloride) (PXT). This work included the fabrication of quasi-periodic two-dimensional structures with potential for photonic applications. However, the thermochemical technique now developed (Scanning Thermal lithography, or SThL) enables one to bypass the UV insolubilisation step, and the complications and additional costs imposed by the needs for lasers, optics, and sophisticated optical fibre probes.

Source: London Centre for Nanotechnology.

Recherchiert und dokumentiert von:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Die Recherche und Aufbereitung der in diesem Dokument genannten Daten erfolgte mit größter Sorgfalt.
Für die Richtigkeit, Gültigkeit, Verfügbarkeit und Anwendbarkeit der genannten Daten übernehmen wir zu keinem Zeitpunkt die Haftung.
Bitte diskutieren Sie die Verwendung und Eignung für Ihren konkreten Anwendungsfall mit den Experten der genannten Institution.

Sie wünschen Material- und Technologierecherchen zu diesem Thema?

Materialsgate steht für hochwertige Werkstoffberatung und innovative Materialrecherchen.
Nutzen Sie unseren Beratungsservice

MMehr zu diesem Thema

The sandwich recipe recently concocted by scientists working at the National Institute of Standards and Technology (NIST) may prove tasty for computer chip designers, who have long had an appetite for molecule-sized electronic components – but no clear way to satisfy it until now.

The research team, which includes collaborators from the University of Maryland, has found a simple method of sandwiching organic molecules between silicon and metal, two materials fundamental to electronic components. By doing so, the team may have overcome one of the principal obstacles in creating switches made from individual molecules, which represent perhaps the ultimate in miniaturization for the electronics industry. The idea of using molecules as switches has been around for years, carrying the promise of components that can be produced cheaply in huge numbers, perform faster as a group than their larger silicon brethren, and use only a tiny fraction of their energy. But although... mehr mehr lesen

From pacemakers constructed of materials that so closely mimic human tissues that a patient's body can't discern the difference to devices that bypass …

injured spinal cords to restore movement to paralyzed limbs, the possibilities presented by organic electronics read like something from a science fiction novel. Derived from carbon-based compounds (hence the term "organic"), these "soft" electronic materials are valued as lightweight, flexible, easily processed alternatives to "hard" electronics components such as metal wires or silicon semiconductors. And just as the semiconductor industry is actively developing smaller and smaller transistors, so, too, are those involved with organic electronics devising ways to shrink the features of their materials, so they can be better utilized in bioelectronic applications... mehr mehr lesen

A simple surface treatment technique demonstrated by a collaboration between researchers at the National Institute of Standards and Technology (NIST), ...

Penn State and the University of Kentucky potentially offers a low-cost way to mass produce large arrays of organic electronic transistors on polymer sheets for a wide range of applications including flexible displays, “intelligent paper” and flexible sheets of biosensor arrays for field diagnostics. In a paper posted this week, the team describes how a chemical pretreatment of electrical contacts can induce self-assembly of molecular crystals to both improve the performance of organic semiconductor devices and provide electrical isolation between devices. Organic electronic devices are inching towards the market. Compounds with tongue-twisting names like “5,11-bis(triethylsilylethynyl... mehr mehr lesen

Researchers have created organic gel nanomaterials that could be used to encapsulate pharmaceutical, food, and cosmetic products and to build 3-D biological scaffolds for tissue engineering. Using olive oil and six other liquid solvents, the scientists added a simple enzyme to chemically activate a sugar that changed the liquids to organic gels.

“We are using the building blocks provided by nature to create new nanomaterials that are completely reversible and environmentally benign,” said Jonathan Dordick, the Howard P. Isermann ‘42 Professor of Chemical and Biological Engineering at Rensselaer Polytechnic Institute. “The importance of this finding is the ability to use the same naturally occurring enzyme both to create chemically functional organogels and to reverse the process and break down these gels into their biologically compatible building blocks.” In the experiments, researchers activated a sugar using a simple enzyme, which generated a compound that self-assembles into 3-D fibers measuring approximately 50 nanometers... mehr mehr lesen

Partner der Woche

Materialsgate Login