Luminescence Properties of the Mixed J-Aggregate of Two Kinds of Cyanine Dyes in Layer-by-Layer Alternate Assemblies

Abstract

The layer-by-layer alternate assemblies incorporating two kinds of cyanine dyes have been fabricated by alternately adsorbing a cationic polyelectrolyte and anionic cyanine dyes on the quartz plate. A thiacyanine dye (dye I) was employed as the donor and two kinds of thiacarbocyanine dye having a meso-alkyl groups m-ethyl (dye II), m-methyl (dye III)sas the acceptor. The mole fraction of the acceptor in the mixed J-aggregate, χ, was varied from 0 to 1. It is confirmed that these dye combinations form the mixed J-aggregate in the alternate assemblies. From steady-state fluorescence spectra of the molecular assemblies, excitation energy transfer from the donor J-aggregate to the acceptor J-aggregate is observed, whose kinetics obeys the Stern-Volmer relationship. The experimentally determined rate constant of energy transfer, k ET , is fairly large, indicating efficient energy transfer due to exciton migration through the donor J-aggregate. The relative fluorescence quantum yield and the fluorescence lifetime of the acceptor aggregate decrease with increasing χ, implying the considerable self-quenching of acceptor fluorescence. The relative change of the coherent size of the dye II aggregate has been estimated from the J-band line width and the radiative decay rate constant. It is found that the coherent size of the dye II aggregate is increased by a factor of 4-5 with increasing χ from 0.008 to 1.

Exciton delocalization of the J‐aggregate of oxacyanine dye and thiacyanine dye in LB films

“…Absorption and fluorescence spectra of LB films on the quartz plate were measured by a V-530 spectrophotometer (JASCO) and a FP-750 fluorimeter (JASCO), respectively. Picosecond fluorescence lifetime measurements were carried out by the method of time-correlated single-photon counting as before [12]. Fluorescence decay curve was fitted to the multiple exponential function convoluted with the instrumental response function.…”

“…2 Therefore, we can state that energy transfer and trapping of molecular excitons obey the Stern -Volmer kinetics when small amount of S11 are doped into the S9(J). The rate constant of energy transfer k ET = 1.5 × 10 13 nm 2 molecules -1 s -1 is fairly large [12]. In view of the Stern -Volmer constant K SV = 1200 nm , it is suggested that the molecular exciton of S9(J) (N cohe = 22) can move over about 2000 donor molecules (incoherent size N inco = 2000) within the lifetime governed by quenching with S11.…”

“…Fluorescence lifetime of S9(J) in Table 1 is considerably decreased with increasing x, which is consistent with quenching of resonance fluorescence by S11. The following relations in the Stern-Volmer kinetics have been well-known [12]:…”

Simulation of energy transfer in disordered two‐dimensional mixed J‐aggregates

“…A computational study of energy transfer and trapping in two-dimensional J-aggregates was performed in order to simulate the luminescent properties of such aggregates [7]. Recently, the luminescence properties, at room temperature, of mixed J-aggregates of two kinds of cyanine dyes were examined [8][9][10]. In general, these aggregates of finite size are characterized by relatively short stacking distances between the chromophores, leading to strong intermolecular interactions because of the long range dipole-dipole couplings.…”

On the Complementary Photoluminescent and Electroluminescent Images of Poly(phenylenevinylene)-Based Light-Emitting Diodes with a Thin Active Layer

“…1, a) and its J-aggregates. This dye is well-known to form different kinds of J-aggregates in solution [10] [11] as well as in LB [12] and selfassembled [13] [14] films. The choice of THIATS allowed us to prepare a stable solution of J-aggregates and pre-PPV in H 2 O, while it was not possible for the dye 5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-bis(4-sulfobutyl)benzimidazolocarbocyanine (TDBC) [15] [16] due to incompatibility of the pH of the mixed compounds.…”