Exciton bimolecular annihilation dynamics in supramolecular nanostructures of conjugated oligomers

We present femtosecond transient absorption measurements on $\pi$-conjugated supramolecular assemblies in a high pump fluence regime. Oligo(\emph{p}-phenylenevinylene) monofunctionalized with ureido-\emph{s}-triazine (MOPV) self-assembles into chiral stacks in dodecane solution below 75$^{\circ}$C at a concentration of $4\times 10^{-4}$ M. We observe exciton bimolecular annihilation in MOPV stacks at high excitation fluence, indicated by the fluence-dependent decay of $1^1$B$_{u}$-exciton spectral signatures, and by the sub-linear fluence dependence of time- and wavelength-integrated photoluminescence (PL) intensity. These two characteristics are much less pronounced in MOPV solution where the phase equilibrium is shifted significantly away from supramolecular assembly, slightly below the transition temperature. A mesoscopic rate-equation model is applied to extract the bimolecular annihilation rate constant from the excitation fluence dependence of transient absorption and PL signals. The results demonstrate that the bimolecular annihilation rate is very high with a square-root dependence in time. The exciton annihilation results from a combination of fast exciton diffusion and resonance energy transfer. The supramolecular nanostructures studied here have electronic properties that are intermediate between molecular aggregates and polymeric semiconductors

Gűlisar: een geval apart?

Contains fulltext : 43025.pdf (publisher's version ) (Open Access)6 p

Hoe leer je een tweede taal

Contains fulltext : 42365.pdf (publisher's version ) (Open Access

Wat was er in den beginne? Over de rol van de eerste taal bij de verwerving van een tweede taal

Contains fulltext : 165249.pdf (publisher's version ) (Open Access)8 p

RALFI in de ANT2-klas?

Contains fulltext : 68385.pdf (publisher's version ) (Open Access)3 p

Het Haalbaarheidsonderzoek van De Voortwijzer

Contains fulltext : 78993.pdf (publisher's version ) (Open Access)19 p

Een taaldidactische beoordeling van de leergang "Nederlandse Gebarentaal voor Algemeen Belangstellenden", met aanbevelingen en suggesties voor verdere ontwikkeling

Contains fulltext : 44107.pdf (publisher's version ) (Open Access)20 p

Conservation of grammatical knowledge: on the acquisition of possessive noun phrases by Turkish and Moroccan learners of Dutch

Contains fulltext : 151670.pdf (publisher's version ) (Open Access