J-aggregates of cyanine dyes attract special attention of the researchers due to their high efficiency in transfer of excitation energy in molecular heterogeneous systems. Formation of a narrow absorption peak – J peak – which is bathochromically shifted relative to the absorption of monomeric form of a dye is the main characteristic of J-aggregation.
The cyanine dye 1,1'-diethyl-2,2'-quinocyanine (pseudoisocyanine - PIC) is known as the dye which form molecular aggregates in aqueous solutions efficiently. PIC J-aggregates can be formed in aqueous solutions and frozen water and ethylene glycol glasses. However, the methods of J-aggregate formation in aqueous solutions or frozen glasses do not give stable reproducible samples, which impede their use as optical or non-linear materials. To study and apply non-linear optical properties of J-aggregates it is necessary to have solid, stable and reproducible samples. Novosibirsk Institute of Organic Chemistry of the Siberian Branch of RAS has developed a new method of producing stable solid nanometer PIC J-aggregate films of high optical quality in both pure form and in polymeric matrixes and studied their optical, thermal and non-linear optical properties.
For the first time there have been obtained the samples of stable nanometer PIC J-aggregate films with controlled width of molecular exciton absorption.
| The method of obtaining J-aggregates
in thin films
|The structure of aggregate with narrow excitonic line|
J-aggregates are viewed as effective non-linear optical media. Non-linear materials can be applied in the creation of ultrafast optical switching devices for the next-generation telecommunication systems and the systems of optical coherent signal processing parallel to the time of picosecond or a hundred of femtoseconds.
Films and spectrum of exiton absorption of J-aggregate
A unique combination of high nonlinearity value |χ(3)| ~ 10-5 ESU with ultrafast (~300 fs) relaxation time makes it possible to use nanodimensional J-aggregates of cyanine dyes in photonics.
There are four main advantages of using cyanine dyes J-aggregated films as non-linear optical switches:
- the use of ultrashort pulses (<1 ps) of light excitation
- availability of high values of non-linear absorption and refraction in J-aggregates
- fast relaxation time (<1 ps) of non-linear response of J-aggregates
- accessibility of obtaining optical films on a large square
Aggregated films can be obtained in the quantity from the dozens to the hundreds of 2.5x2.5 sm. pilot samples on glass base. Contracted price per a film sample depends on the type of dyes (from 300 rubles)
N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry,
Siberian Branch of the Russian Academy of Sciences
9, Acad. Lavrentiev Ave, 630090, Novosibirsk, 90, Russsia PhD. Vladimir Vladimirovich Shelkovnikov, Head of the Laboratory