TY  - JOUR
A1  - Plötz, P.-A.
A1  - Polyutov, S. P.
A1  - Ivanov, S. D.
A1  - Fennel, F.
A1  - Wolter, S.
A1  - Niehaus, T.
A1  - Xie, Z.
A1  - Lochbrunner, S.
A1  - Würthner, Frank
A1  - Kühn, O.
T1  - Biphasic aggregation of a perylene bisimide dye identified by exciton-vibrational spectra
JF  - Physical Chemistry Chemical Physics
N2  - The quantum efficiency of light emission is a crucial parameter of supramolecular aggregates that can be tuned by the molecular design of the monomeric species. Here, we report on a strong variation of the fluorescence quantum yield due to different phases of aggregation for the case of a perylene bisimide dye. In particular, a change of the dominant aggregation character from H- to J-type within the first aggregation steps is found, explaining the observed dramatic change in quantum yield. This behaviour is rationalised by means of a systematic study of the intermolecular potential energy surfaces using the time-dependent density functional based tight-binding (TD-DFTB) method. This provides a correlation between structural changes and a coupling strength and supports the notion of H- type stacked dimers and J-type stack-slipped dimers. The exciton-vibrational level structure is modelled by means of an excitonic dimer model including two effective vibrational modes per monomer. Calculated absorption and fluorescence spectra are found to be in reasonable agreement with experimental ones, thus supporting the conclusion on the aggregation behaviour.
KW  - Potential-energy curves
KW  - Simulations
KW  - Molecular-dynamics
KW  - Systems
KW  - Fluorescence
KW  - Sracking
KW  - Pathway
KW  - Dimers
KW  - State
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187387
VL  - 18
IS  - 36
ER  - 
TY  - JOUR
A1  - Harkin, David J.
A1  - Broch, Katharina
A1  - Schreck, Maximilian
A1  - Ceyman, Harald
A1  - Stoy, Andreas
A1  - Yong, Chaw-Keong
A1  - Nikolka, Mark
A1  - McCulloch, Ian
A1  - Stingelin, Natalie
A1  - Lambert, Christoph
A1  - Sirringhaus, Henning
T1  - Decoupling charge transport and electroluminescence in a high mobility polymer semiconductor
JF  - Advanced Materials
N2  - Fluorescence enhancement of a high-mobility polymer semiconductor is achieved via energy transfer to a higher fluorescence quantum yield squaraine dye molecule on 50 ps timescales. In organic light-emitting diodes, an order of magnitude enhancement of the external quantum efficiency is observed without reduction in the charge-carrier mobility resulting in radiances of up to 5 W str\(^{-1}\) m\(^{-2}\) at 800 nm.
KW  - Light-emitting diodes
KW  - Fiels-effect transistors
KW  - Energy transfer
KW  - Conjugated polymers
KW  - High performance
KW  - High efficiency
KW  - Perovskite
KW  - Amplification
KW  - Fluorescence
KW  - Emission
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187670
VL  - 28
IS  - 30
ER  -