Hannover 2020 – scientific programme
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MO: Fachverband Molekülphysik
MO 8: MO Poster 2
MO 8.16: Poster
Tuesday, March 10, 2020, 17:00–19:00, Empore Lichthof
Exciton Dynamics in Squaraine-based Thin Films — •Steffen Wolter1, Manuela Schiek2, and Stefan Lochbrunner1 — 1Institute of Physics, University of Rostock, 18051 Rostock, Germany — 2Institute of Physics, Carl von Ossietzky University of Oldenburg, 26111 Oldenburg, Germany
Squaraine dyes are promising candidates for light harvesting electron donor materials in small molecule solar cells, since they combine strong absorption in the visible spectral region with a high stability compared to other organic compounds like low bandgap polymers. Bulk-heterojunction solar cells based on squaraine:fullerene blends have been shown to suffer from low mobility and recombination losses [1]. In depth understanding of the loss mechanism requires investigation of fundamental processes upon light absorption on ultra-fast time scales.
In this contribution, the light induced processes in different squaraine based thin films are investigated by femtosecond pump-probe spectroscopy. The dynamics in pure films of 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQIB) is studied to obtain a picture of the possible electronic relaxation pathways in the donor material. In a next step, the results are compared to films of SQIB blended with a fullerene acceptor (PCBM). Strong differences in the kinetics and the spectral signatures are observed and attributed to the population of charge separated states.
[1] Scheunemann, Kolloge, Wilken, Mack, Parisi, Schulz, Lützen, Schiek. Appl. Phys. Lett. 111 (2017) 183502.