Mechanistic Study of Excitation Energy Transfer in Dye-Doped PPV Polymers

Abstract

The mechanism of excitation energy transfer is studied using host-guest systems consisting of green and yellow emitting poly(phenylene vinylene) (PPV) based polymers into which red emitting dyes are dispersed. The photoluminescence from such polymer-dye systems is studied in the steady-state and time resolved. Furthermore, the electroluminescence from devices containing these polymer-dye systems as emissive layer is measured. It is shown that in such disordered polymers, characterized by dispersive exciton transport, energetic resonance between the polymer and the dye is not the only requisite for efficient energy transfer. In addition, the exciton kinetics of the combined polymer-dye system has to be taken into account. Efficient transfer of excitation energy from a disordered polymer to a dye can only occur if, at a certain energy, the polymer-to-dye exciton transfer rate is higher than the intrapolymer exciton migration rate. A consequence of the mechanism described here is that when a dye is dispersed into a disordered polymer, always a residual polymer emission remains, both in photoluminescence as well as in electroluminescence, provided that excitons are created on the polymer. This knowledge is important when constructing a device employing such a polymerdye system as the emissive layer.

Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation

“…The exciton diffusion is enhanced in the early time by downhill migration to lower energy chain segments and then once the excitons are thermalized, slower diffusion takes over. 34,35 This time dependence of the exciton diffusion contributes to the observed time dependence of ␥͑t͒, keeping the annihilation rate higher for longer while the excitons are able to move faster due to the dispersive component in the migration. At longer times after the dispersive migration is over, the annihilation rate tends toward the theoretical constant value given by Eq.…”

Multicolor Emission on Prepatterned Substrates Using a Single Dye Species

“…It is known that polymers can be stained with dye molecules by emerging the polymer into the dye solution or by mixing polymers and dyes in the liquid phase. [30,31] In both cases, dye molecules will often stay in the monomer state because they are able to diffuse into the free space of the bulk polymer. To the best of our knowledge, there are no published data concerning the emission spectra of dye films deposited on polymer substrates by gas-phase evaporation, although diffusion of metals into polymers via gas-phase deposition is well documented.…”

Non-radiative resonance energy transfer in bi-polymer nanoparticles of fluorescent conjugated polymers

“…Since the efficiency of radiative energy transfer is relatively low compared to RET efficiency, the latter mechanism will be of major concern in our study though Förster theory is not necessarily the only mechanism valid in our systems under investigation. Hybrid systems consisting of donor polymer molecules and acceptor dye molecules for energy transfer have been thoroughly studied since several years [6][7][8][9][10][11][12][13]. These systems are mainly mixtures of donor and acceptor solutions, so that energy transfer takes place among random mixing proximal donor and acceptor molecules [3,4].…”