Optical and photoelectric properties of multichromic cyanine dye J-aggregates

Abstract

We report the results of investigation of spectra and kinetics of photoluminescence as well as of photoabsorption and photoelectric properties for multichromic molecular crystals consisting of J-aggregates of three cyanine dyes with various structures. An original ‘self-assembly’ method is used for fabricating such prolate ordered structures with a thickness of 5 – 100 nm, width of 0.1 – 5 μm, and length of 50 – 300 μm. The method is based on the formation of the anionic platform in a water solution, which absorbs light in the blue spectrum range and comprises J-aggregates of magnesium complexes of anionic cyanine dye. Then the ‘matrix synthesis’ is used for coating its surface with J-aggregates of the two cationic dyes that have the absorption maxima in the green and red spectral ranges. It is shown that each of the multichromic organic crystals produced in this way is a multilayer photoelement, which possesses photoconductivity in three excitonic absorption maxima (in the blue, green, and red spectral ranges) with the external quantum efficiency varying from 2.7 % to 6.1 %. The results obtained provide a basis for technological development of highly-ordered molecular structures, which are promising for using in organic and hybrid photonics and optoelectronics including thin-film photo-converters operating in wide spectral ranges.