Apr 7, 2009
Microstructures control growth of organic light-emitting nanofibres
The production of inorganic nanowires from silicon or III-V materials has so far enabled numerous nanowire-based prototypes such as sensors, solar cells and transistors, often with smaller and more-effective designs than ever before. However, nanofibres made from organic materials could provide even more design flexibility. Fabricating such nanostructures from organic molecules can add significantly to their functionality by making use of established organic synthesis techniques.
Device integration typically takes place in one of two ways – either by controlled transfer of the nanostructures from the growth substrate to the desired device platform or by in situ growth directly on the platform where they are needed, but issues remain and present an obstacle to commercial success.
Researchers in Denmark have recently made progress on the in situ route and reveal how structuring of the growth substrate at the micrometre scale can provide a useful way of controlling the alignment process. In a recent study published in Nanotechnology, the group has described a method for growing organic, blue light emitting nanofibres in situ on a demonstration device platform.
The fibres are grown from vacuum sublimation on gold films, on which – without any sample pre-structuring – fibres grow only in a random fashion. However, by structuring the substrate on a micrometer scale prior to growth and with appropriate heating of the substrate, the nanofibres' growth direction can be guided into preferred directions. Hence, a novel and generic technique for controlled nanofibre growth is established.
One of the major benefits of this method is that the microstructures are made on a silicon platform. Therefore, standard, well established micro-fabrication techniques can be used: optical lithography, reactive ion etching and gold deposition by e-beam evaporation. This wafer-scale structuring of the platforms enables high throughput, leading to controlled, large-scale, in situ growth of organic nanofibres on device platforms. The method therefore opens up a new way of fabricating devices such as sensors, transistors or solar cells based on organic nanofibres.
About the author
This work was done within the nanotechnology center NanoSYD at the Mads Clausen Institute, University of Southern Denmark. Morten Madsen is a PhD student focusing on growth and integration of organic nanofibres. Jakob Kjelstrup-Hansen is an assistant professor working on integration of nanostructures and Horst-Guenter Rubahn is a professor of physics at the University of Southern Denmark and head of NanoSYD.