Intramolecular excimer emission of poly(N-vinylcarbazole) and rac- and meso-2,4-di-N-carbazolylpentane. Model substances for its syndiotactic and isotactic dyads

Effect of distance between acceptor and donor on optical properties of composite semiconducting polymer films

“…decay of the pure PVK film is multi-exponential, indicating that there are multi-excitations. A full overlap configuration and a partial overlap configuration of two adjacent carbazole groups are responsible for the excitations with different life times in PVK [22][23][24]. The average decay time of the PVK/Alq 3 (8%) film without PMMA is markedly decreased because the excitations in PVK are quenched by Alq 3 .…”

Thermoluminescence of poly(9-vinylcarbazole) modified by substitution with halogens

“…At the same time, Johnson [31] and Itaya et al [32,33] have proposed two types of excimer species: so called ''sandwich-like excimers" (or full-overlap excimers) characterised by a coplanar sandwich-type arrangement of two neighbouring carbazole rings and ''second excimers" (or partial-overlap excimers) created by the overlap of only one benzene ring from two neighbouring chromophores in the tt conformation of the syndiotactic sequence in PVK. The existence of two emitting species in PVK was confirmed in the works by De Schryver et al [34] and Evers et al [35], where the emission of two model compounds: rac-2,4-bis(carbazol-9-yl)pentane and meso-2,4-bis(carbazol-9-yl)pentane was studied and related to the two excimeric emissions observed in PVK. Photophysical properties of two types of carbazole excimers have also been investigated using other models -carbazolophanes with clearly defined geometrical alingments of two carbazole moieties [36].…”

The broadened and red-shifted photoluminescence spectral emission of poly(N-vinylcarbazole) nanoparticles

“…Compared to the PVK solution and film, the PL spectrum of the PVK nanoparticles becomes wide and its PL peak red shifts to 430 nm. The 430 nm PL band has been considered to be connected with intrachain excimers, in which the two neighboring carbazole groups in one polymer chain form a full overlapping, sandwich configuration [15][16][17]. During the preparation of the polymer nanoparticles, a small quantity of the PVK THF solution is injected into a great quantity of water.…”

“…The excited states in PVK have been considered as excimers owing to the closed carbazole groups. Two configurations are responsible for the excimers in PVK namely, an excimer with a low-energy emission band (430 nm) that comprises an overlapping, sandwich-like configuration of two carbazole groups and an excimer in which the partial overlap of two carbazole groups is responsible for the observed, high-energy emission band (380 nm) [15][16][17]. The 380-nm emission band has been found to be dominant in the photoluminescence (PL) spectra of syndiotactic PVK, whereas, the intensity of the 430-nm emission band increases with increasing mole fraction of the isotactic diads in PVK [16].…”