Heidelberg 2015 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 5: Posters 1: Novelties in Molecular Physics
MO 5.6: Poster
Montag, 23. März 2015, 17:00–19:00, C/Foyer
Acceleration of Singlet Fission in an Aza-Derivative of TIPS-Pentacene — •Julia Herz1, Fabian Paulus2, Jens Engelhart2, Tiago Buckup1, Uwe Bunz2, and Marcus Motzkus1 — 1Physikalisch-Chemisches Institut — 2Organisch-Chemisches Institut, Ruprecht-Karls-Universität, D-69120 Heidelberg, Germany
Singlet fission plays a prominent role in raising the quantum efficiency of organic solar cells. In this overall spin-conserved process two molecules in the triplet state T1 are formed by investing just one photon. Pentacene is known to undergo singlet fission and is an attractive starting compound to develop new chromophores with promising photo-physico-chemical qualities. By means of ultrafast transient absorption measurements with high time resolution, we provide a detailed picture of the excited state dynamics of TIPS-pentacene [1], an important, soluble derivative of pentacene. A kinetic model was derived by carrying out a global target analysis. Furthermore, we found that a carbon to nitrogen substitution has a high impact on the triplet formation and leads to faster initial dynamics. The chemical modification can accelerate singlet fission in the aza-derivative by almost a factor of two. A faster relaxation from the singlet to triplet manifold implies a higher efficiency, because other relaxation channels are avoided. A stronger triplet signal in the near infrared spectral region relative to that in the visible indicates a higher quantum yield when compared to TIPS-pentacene, making the more air-stable aza-derivatives promising for organic electronics applications. [1] Herz et al, JPC Let. 5 (2014) 2425.