TY  - GEN
N2  - Excited state dynamics of organic materials were studied using time-resolved spectroscopic techniques. The processes involved, such as charge separation (CS), charge recombination (CR) and singlet fission (SF) play a key role in developing and improving organic electronics such as light-harvesting devices. To study the impact of the relative orientation of organic chromophores on singlet fission (SF), substituted pentacene (PEN) was used as linker in a surface-anchored metal-organic framework (SURMOF). This allowed to arrange the PEN molecules in a slip-stacked configuration. It was found, that the SF dynamics were altered appreciably. The SF rate was slowed down by almost two orders of magnitude and the triplet life time was increased by more than three orders of magnitude. Furthermore, CS and CR dynamics were investigated in a porphyrin-based SURMOF, incorporating C60 in the pores. The CS occurred via a direct pathway without the population of the porphyrin triplet state. The CS was found to be very fast with a time constant of ?300 fs and the CR took place with time constants between 200 and 400 ps. CS and SF were further investigated in bilayers of PEN with strong acceptors. In the ground state, formation of ion-pairs as well as the formation of charge transfer complexes were observed. The SF dynamics in PEN were only marginally slowed down to 158-222 fs. Within a few dozens of picoseconds, CS at the interface between PEN and the acceptor layer was identified by observation of a shift in optical absorption due to the Stark effect. Lastly, second-order non-linear optical properties of chiral cage compounds were investigated. Second-harmonic generation rotatory dispersion experiments reveal a rotation over 20°. The explanation of the data obtained regarding the interaction with circularly polarised light required magnetic dipole contributions.
AV  - public
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/35904/
Y1  - 2025///
ID  - heidok35904
A1  - Richter, Martin
TI  - Ultrafast Dynamics of Optically Excited States in Organic Semiconductors
CY  - Heidelberg
ER  -