Emission properties of vinylcarbazole polymers

Abstract

The emission properties of poly(N-vinylcarbazole) (PVK), poly(N-ethyl-2-vinylcarbazole), and poly(N-ethyl-3-vinylcarbazole) have been investigated. Dilute fluid solutions of all three vinylcarbazole polymers are observed to exhibit a structureless emission band at energies approximately 5400 cm−1 to the red of the (0,0) band of the normal molecular fluorescence of isolated monomer compounds. On the basis of earlier work appropriate model compounds, this emission is assigned as that from an intrachain excimer state in which two interacting pendant groups, one of which is electronically excited, achieve an overlapping, eclipsed, sandwichlike configuration. The emission spectrum of PVK is characterized by the appearance of a second structureless emission band which appears at higher energy than the intrachain excimer fluorescence common to all three vinylcarbazole polymers. This emission band is unique to PVK and under certain conditions to its model compound, 1,3-bis(N-carbazolyl)propane. This emission is assigned as that from a second intrachain excimer. Contrary to the lower energy intrachain excimer, the polymer conformation appropriate for formation of this state exists prior to the initial excitation step.

Synthesis and photophysical properties of a poly(methyl methacrylate) polymer with carbazolyl side groups

“…Several reports have invoked a PVCz excimer of this type; in the suggested geometry, only one aromatic ring of each aromatic moiety is overlapped. 25,27,29,31 As expected, emission from both excimer types is attenuated by higher temperatures.In conclusion, the temperature dependence of the emission spectra and from the photophysical behavior observed by site-selective and time-resolved spectroscopy on the millisecond and nanosecond time scales is consistent with the simplified mechanistic steps shown in Scheme 2. Accordingly, absorption of incident radiation by the isolated (M) and ground-state aggregate (D) species produces , respectively, in amounts controlled by the products of their molar extinction coefficients and concentrations (i.e., by Beer's Law); it is reasonable to assume that the molar extinction coefficient of D is twice that of M at each wavelength.…”

Solution processed multilayer polymer light-emitting diodes based on different molecular weight host

“…17,18 By doping this system with Ir complex, that is, Ir(ppy) 3 , electrons from PBD are strongly trapped at the LUMO (triplet spin multiplicity) of the Ir(ppy) 3 , (À2.8 eV); similarly holes at PVK are trapped at the HOMO level of the Ir(ppy) 3 (À5.22 eV), generating phosphorescent excitons, and only EL emission from Ir(ppy) 3 centered at 512 nm (2.42 eV) was observed with no emission from the PVK excimer at 400 nm or from the exciplex at 430 observed even at low (<1%) Ir(ppy) 3 concentration.…”

Structure and Luminescence Properties of Poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene)

“…The luminescence of PHDP is very comparable with that of poly(N-vinylcarbazole) (PVK), which is widely used as a sensitizer 13 and emitter. 14,15 Like PHDP, PVK in THF excited at UV wavelengths produces blue emission in the 360-500 nm region, as shown in Figure 1. Figure 2 shows the excitation spectra of the 420-nm emissions from the monomer and polymer.…”