BPCPPDYSOE21 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Poster Session I - Molecular Electronics and Wetting
CPP 6.13: Poster
Montag, 22. März 2021, 16:30–18:30, CPPp
Simulation of light-induced exciton diffusion and quenching on SWCNTs — •Manuel Rommel1, Ralph Krupke1,2, and Wolfgang Wenzel1 — 1Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe — 2Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt
The diffusion of excitons and charge carriers and the exciton loss processes like decay and quenching play an important role for the current characteristics in systems with light-induced charge carriers. A power-dependent photocurrent measurement on polymer-wrapped semiconducting single walled carbon nanotubes (SWCNT) has revealed a sublinear scaling of the electric current with laser power.
Here, we present a modified Monte-Carlo-based simulation with a fixed timestep and a pulsed laser. It models the stochastical generation, diffusion, collision and quenching of excitons, electrons and holes in 1D. Our results show that there are two regimes depending on laser power. At low laser power, current scales linearly with laser power. For high laser power (which coincides with the onset of exciton-exciton-quenching), the exponent of the power dependence becomes 0.63, which is very close to the experimental value of 0.59±0.08. Furthermore, we can show that even a perfectly symmetric 1D system, where both electrodes favor the same charge carrier, exhibits a photocurrent if the illumination is asymmetric. We also show that power law characteristics depend on the SWCNT length.
This gives an insight into diffusion in SWCNTs and highlights the importance of exciton-exciton-quenching in SWCNT devices.