11-08 :: August 2011

nanotimes EU-Projects

tion services for content requiring a higher degree of confidentiality and protection. Practical realisation of QKD technology relies on availability of systems providing production, propagation and detection of individual light particles single photons. Single pho- ton sources based on nano-structured materials such as quantum dots, carbon nanotubes and diamond nanowires that have enabled the development, and recent demonstration, of a small number of com- mercial products. The working distance of existing technologies is currently limited to around 100km; significant development in fibre optics is required to make further advances here. The costs involved in developing QKD-based products also make it im- practical for mainstream applications and, for now, these applications are limited to use by major finan- cial institutions, national security and other govern- ment agencies.

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light. The researchers involved in the international FINELUMEN project, coordinated by Dr. Nicola Armaroli from Italy‘s Istituto per la Sintesi Organica e la Fotoreattivita, Consiglio Nazionale delle Ricerche (CNR-ISOF) in Bolonia, have developed an efficient method to fabricate a new photonic material: carbon nanotubes coated with chemicals that are capable of displaying red light. “We take part at the project as a research group specializing in studies on lanthani- de compounds. We decided to combine their high luminescent properties with excellent mechanical and electrical characteristics of nanotubes,” says Prof. Marek Pietraszkiewicz from Warsaw“s Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS).

Red Light from CNTs – FINELUMEN Project

To the human eye, carbon nanotubes usually appear as a black powder. They can hardly be forced to emit light, as they are excellent electrical conductors and capture the energy from other luminescent chemi- cal species placed nearby.The researchers from the Institute of Physical Chemistry of the Polish Aca- demy of Sciences in Warsaw contributed recently to the development of a relatively simple method allowing the nanotubes exposed to UV to emit red

“Attachment of light-emitting complexes directly to the nanotube is, however, not favourable, because the latter, as a black absorber, would highly quench the luminescence,” explains Valentina Utochnikova, a PhD student at the IPC PAS. To reduce undesired effect of light absorption, the nanotubes are first subject to a thermal reaction at temperature 140 to 160° C in a solution of ionic liquid modified with a terminal azido function. The reaction yields nano- tubes coated with molecules acting as anchors-links. On one side the anchors are attached to the surface of the nanotube, and on the other they can attach molecules capable of displaying visible light. The free terminal of each link bears a positive charge.

So prepared nanotubes are subsequently transferred into another solution containing a negatively charged lanthanide complex - tetrakis-(4,4,4-trifluoro-1-(2- naphtyl-1,3-butanedionato)europium. “Lanthanide compounds contain elements from the VI group of the periodic table and are very attractive for pho-