The effect of addition of
J
-aggregates of polymethine dye into the hole-transport layer of an organic light-emitting diode (OLED) on its characteristics and operational stability was studied. ...Water-soluble PEDOT:PSS (poly(3,4-ethylenedioxythiophene)) and the interpolymer complex of polyaniline and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAn-PAMPSA) were used as the matrices of polymer nanocomposites. The highest efficiency characteristics of the OLEDs with the considered structure were achieved using PAn-PAMPSA at a particular component ratio in the interpolymer complex. Additives of
J
‑aggregates did not significantly affect the efficiency characteristics of the OLEDs; however, an increase in the operational stability of devices was recorded.
A crystallographic analysis of the images of destruction fragments of tubular monomethine dye
J
-aggregates has been performed for the first time. It is shown that the formation of characteristic ...zigzag fragments is caused by the unwrapping of cylindrical surface on plane. Possible cleavage directions for the monolayer forming the tube walls are considered and an interrelation between the destruction products and molecular packing of this monolayer is established.
The structures of
J
-aggregates of two monomethine dyes are compared at the meso- and nanoscale by using fluorescence and atomic force microscopy. The
J
-aggregates of the two dyes are found to have ...solely a monolayer structure and to be polymorphic. Morphologically, monolayers represent narrow skew-symmetric strips and symmetric rhombi in the case of the first and the second dyes. The second morphological type is the tubular type in both cases. For monolayers of both dyes, atomic force microscopy imaging at the ultimate resolution reveals the presence of a quasi-one-dimensional substructure consisting of densely packed nanostrips with a width in the range of 7–10 nm. The nanostrips are interpreted as building blocks emerging at early stages of monolayer crystallization that proceeds via a nonclassical multistep mechanism.
—J-aggregates of a carbocyanine dye (pyridinium salt of 3,3'-di-(γ-sulfopropyl)-4,5,4',5'-di(tieno-3'',2'')-9‑ethyl-tiatrimethine cyanine betaine) (CC) were studied via the high-resolution AFM method ...at the mesoscale and nanoscale. They were found to exist in two structurally different polymorphic forms of single layers and fibrils. The class of single-layer J-aggregates consists of irregular micron sheets and giant submicron tubes, whose structure is identical to tubular J-aggregates of other cyanine dyes. The fibrillar J-aggregates are composed of 3-nm-high fibrils forming the networks owing to merging and branching, as well as of “elementary” fibrils with a height close to the molecular sizes of dye. Structural models of elementary fibril with molecular “staircase” and “ladder” stacking types were proposed as well.
Meso- and nanoscale structural polymorphism of monolayer
J
-aggregates of four cyanine dyes are investigated. Three mesoscale morphological types are observed: ribbons, rhombic leaves, and tubes. ...Tubes are formed during cylindrical spinning of ribbons. Lined substructure characterized by the line width of about 7 nm is found in the case of monolayers of monomethine cyanine dyes at the nanoscale.
It is found that one of the types of molecular organic nanocrystals, the so-called
J
-aggregates, is able to modify optoelectronic properties of electroactive polymers. It is intrinsic that the ...polyaniline interpolymeric complex, known as
p
-type semiconductor, turns into electroluminescent material in the presence of
J
-aggregates of 3,3-di(gamma-sulfopropyl)-5,5-dichlorotiamonomethincyanine triethylammonium salt. During the studying of new organic light-emitting diode structures, in which the polyaniline/
J
-aggregates polymeric composite forms both recombination and emitting layers, a polyaniline intrinsic electroluminescence spectrum is obtained. The electroluminescence band completely coincides with the polyaniline photoluminescence spectrum; it has maximum at 400 nm. The electroluminescence mechanism in the studied nanocomposites is discussed.
A crystallographic analysis of optical fluorescent images of two-dimensional polygonal structures of
J
-aggregates of 3,3′-di(γ-sulfopropyl)-5,5′-dichlorothiamonomethinecyanine (MCD) cyanine dye has ...been performed. In aqueous solutions, MCD forms striplike
J
-aggregates in the form of extended strips with parallel sides and an oblique or right-angled end. It is found that the acute angle in oblique
J
-aggregates has a single value close to 45°. The staircase model of molecular packing in oblique
J
-aggregates is proposed with a slippage angle of 25° expected from the molecular simulation. Within this model the sides of aggregates are formed by the 100 and
faces, and the acute angle between them is equal to the experimentally observed angle. Right-angled rectangular
J
-aggregates are presumably described by the ladder model.
A stabilization effect of petroleum polymer resin on the thermal oxidation of high-pressure polyethylene was found with the frustrated total internal reflection infrared spectroscopy method and from ...the analysis of physicomechanical properties. The kinetics of thermal oxidation and the rate of decrease in physicomechanical properties of polymers in the presence of an Irganox 1010 conventional industrial polyolefin stabilizer and C5–C9 petroleum polymer resin were analyzed comparatively.
The influence of petroleum resin on the thermal oxidation of an ethylene copolymer with vinyl acetate was studied with differential scanning calorimetry, FTIR infrared spectroscopy, and ...physicomechanical tests. We found that the introduction of PPR into EVAC inhibits the accumulation of oxygen-containing groups in the polymer. The use of the resin combined with an Irganox 1010 primary antioxidant makes it possible to maintain the performance of a material after holding at higher temperature for 3 h at a significantly higher level than in the case of only Irganox 1010.
