Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: Organic Electronics and Photovoltaics I - Charge Transport and Electronic Devices
CPP 9.2: Vortrag
Montag, 1. April 2019, 15:30–15:45, H18
The impact of energy barriers at grain boundaries on charge carrier motion in a high-mobility, electron-conductive organic semiconductor — Ilja Vladimirov1, Michael Kühn1, Thomas Geßner1, Falk May1, and •Thomas Weitz2 — 1BASF SE, Ludwigshafen, Germany — 2AG Physics of Nanosystems, Faculty of Physics, LMU München, Germany
Using high-surface tension solvents allowed us to grow 3 * 10 nm thin, highly-crystalline films of a N,N*-di((S)-1-methylpentyl)-1,7(6)-dicyano-perylene-3,4:9,10-bis(dicarboximide) (PDI1MPCN2) at the liquid/air interface of a drying droplet [1]. We find, that charge carrier mobilities in these electron conductive films is as high as 4 cm*/Vs even for an only 3 nm thin PDI1MPCN2 film. Changing the solvent composition used for crystallization of our organic semiconductor also has allowed us to systematically tune the crystallinity and consequently the grain boundary density in thin films. From the temperature-dependent charge carrier mobility, we have extracted the density of states and compared it to Kinetic Monte Carlo simulations [2]. This combined theoretical and experimental approach has allowed us to identify, that it is rather the energetic barriers at grain boundaries than the usually identified traps that limit charge carrier motion. We also have revealed that the dipole moment of the PDI1MPCN2 is the cause for the energetic disorder at grain boundaries serving as clear guideline for future design of organic semiconductors with potentially no energetic barriers present at the grain boundaries. [1] Nano Lett. 18, 9, (2018) [2] Sci. Rep. 8, 14868, (2018)