Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 86: Ultrafast Surface Dynamics I

O 86.1: Talk

Thursday, March 10, 2016, 15:00–15:15, S052

Imaging ultrafast photo-induced dynamics in semiconducting polymer films with time-resolved photoemission electron microscopy — •Andreas Neff and Katrin Siefermann — Leibniz-Institute of Surface Modification, Leipzig, Germany

Organic semiconductors have great potential for applications in optoelectronic devices. By now, it is well established that the performance of devices critically depends on the detailed morphology of the organic semiconducting films [1]. However, a profound understanding of the correlation between morphology and (photo)physical properties is still missing, and this remains a key challenge to overcome technological hurdles in the field.

We address this challenge with a combination of a photoemission electron microscope (PEEM) and a femtosecond laser system. With this setup, we image the morphology of films of organic semiconductors, in particular the size and orientation of crystallites, with a lateral resolution of ∼100 nm. Ultrafast pump-probe experiments allow us to image photo-induced dynamics with a temporal resolution of 150 fs and a lateral resolution of ∼100 nm. Here, we present results from the ultrafast exciton decay dynamics in P3HT (Poly(3-hexylthiophen-2,5-diyl)) films. We find that these decay dynamics are - as expected but not previously detectable - not the same for all locations on the sample. These results demonstrate the potential of time-resolved PEEM to address key questions with regard to the relationship between nanoscale morphology of organic semiconductors and photo-physical properties.

[1] Y. Diao et al., Nat. Commun. 6, 7955 (2015).