Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 2: Electronic Spectroscopy I

MO 2.3: Vortrag

Montag, 18. März 2013, 11:30–11:45, F 107

Delayed fluorescence from single-wall carbon nanotube-polymer conjugates — •Florian Späth¹, Dominik Stich¹, Daniel Schilling¹, Hannes Kraus², Andreas Sperlich², Vladimir Dyakonov^2,3, and Tobias Hertel¹ — ¹Institute of Physical and Theoretical Chemistry, Julius-Maximilian University Würzburg, Germany — ²Institute of Physics, Julius-Maximilian University Würzburg, Germany — ³Bavarian Center for Applied Energy Research e.V., Würzburg, Germany

Dispersion of single-wall carbon nanotubes (SWNTs) in polyfluorene solutions is a convenient route towards monodisperse SWNT samples. Time-correlated single photon counting experiments of SWNT PL reveal a long-living PL component, which is significantly enhanced in these SWNT-polymer conjugates if compared to surfactant-stabilized SWNTs embedded in gelatin films. For the gelatin-embedded SWNTs, the PL decay is attributed to delayed fluorescence (DF) by triplet-triplet annihilation. We suggest, however, that excited state dynamics in SWNT-polymer conjugates are more significantly affected by charge carrier recombination.

Optically detected magnetic resonance (ODMR) experiments provide evidence of both triplet excitons and free charge carriers in optically excited SWNTs. Ground state recovery in transient absorption experiments suggest that photo-generated charge carriers in gelatin-embedded SWNTs are most likely trapped, while their mobility in SWNT-polyfluorene conjugates is higher and leads to more frequent carrier recombination.