TY  - JOUR
A1  - Hoche, Joscha
A1  - Flock, Marco
A1  - Miao, Xincheng
A1  - Philipp, Luca Nils
A1  - Wenzel, Michael
A1  - Fischer, Ingo
A1  - Mitric, Roland
T1  - Excimer formation dynamics in the isolated tetracene dimer
JF  - Chemical Science
N2  - The understanding of excimer formation and its interplay with the singlet-correlated triplet pair state \(^{1}\)(TT) is of high significance for the development of efficient organic electronics. Here, we study the photoinduced dynamics of the tetracene dimer in the gas phase by time-resolved photoionisation and photoion imaging experiments as well as nonadiabatic dynamics simulations in order to obtain mechanistic insight into the excimer formation dynamics. The experiments are performed using a picosecond laser system for excitation into the S\(_{2}\) state and reveal a biexponential time dependence. The time constants, obtained as a function of excess energy, lie in the range between ≈10 ps and 100 ps and are assigned to the relaxation of the excimer on the S\(_{1}\) surface and to its deactivation to the ground state. Simulations of the quantum-classical photodynamics are carried out in the frame of the semi-empirical CISD and TD-lc-DFTB methods. Both theoretical approaches reveal a dominating relaxation pathway that is characterised by the formation of a perfectly stacked excimer. TD-lc-DFTB simulations have also uncovered a second relaxation channel into a less stable dimer conformation in the S\(_{1}\) state. Both methods have consistently shown that the electronic and geometric relaxation to the excimer state is completed in less than 10 ps. The inclusion of doubly excited states in the CISD dynamics and their diabatisation further allowed to observe a transient population of the \(^{1}\)(TT) state, which, however, gets depopulated on a timescale of 8 ps, leading finally to the trapping in the excimer minimum.
KW  - excimer formation
KW  - tetracene dimer
KW  - organic electronics
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-251559
VL  - 12
IS  - 36
SP  - 11965
EP  - 11975
ER  -