Abstract

In optoelectronic devices charge carriers are converted into light by forming excitons, for example in lasers and LEDs, or light is absorbed and excitons are converted into charge carriers when considering photodiodes and solar cells. Optical spectroscopy is a formidable experimental tool to understand light matter interaction and exciton dynamics, but less common for probing charge carriers.

In this seminar I will present recent experiments based on mid-infrared optical spectroscopy (1.3-0.3 eV photon-energy) aiming to detect and study charge carrier dynamics in graphene materials and conjugated polymers. In the case of graphene, infrared optical pulses are used to understand carrier cooling after photoexcitation¹ and measure the hot carrier lifetime². For conjugated polymers, the photoinduced generation of polaron-pairs in donor acceptor copolymers is addressed considering the role of molecular structure³ and excess photon energy⁴.

References

[1] T. Limmer, A. J. Houtepen, A. Niggebaum, R. Tautz, E. Da Como, Appl. Phys. Lett. 2011, 99, 103104. [2] T. Limmer, J. Feldmann, E. Da Como, Phys. Rev. Lett. 2013, 110, 217406. [3] R. Tautz, E. Da Como, T. Limmer, J. Feldmann, H.-J. Egelhaaf, E. von Hauff, V. Lemaur, D. Beljonne, S. Yilmaz, I. Dumsch, S. Allard, U. Scherf, Nat Commun 2012, 3, 970. [4] R. Tautz, E. Da Como, C. Wiebeler, G. Soavi, I. Dumsch, N. Frohlich, G. Grancini, S. Allard, U. Scherf, G. Cerullo, S. Schumacher, J. Feldmann, J. Am. Chem. Soc. 2013, 135, 4282-4290.