Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 57: Organic Electronics and Photovoltaics IV - Excitonic Properties and Light-Emitting Devices
CPP 57.11: Vortrag
Donnerstag, 4. April 2019, 17:45–18:00, H18
Homocoupling defects limit exciton diffusion in a conjugated polymer — •Martin Streiter1, Fabian Meier1, Daniel Beer1, Caroline Lienert2, Florian Lombeck2, Michael Sommer2, and Carsten Deibel1 — 1Institut für Physik, Technische Universität Chemnitz, 09126 Chemnitz, Germany — 2Institut für Makromolekulare Chemie, Universität Freiburg, 79104 Freiburg, Germany
Exciton diffusion has been studied in a range of conjugated polymers. It is both, of fundamental interest and an important step relevant for high performance organic solar cells. Copolymers such as PCDTBT are commonly employed as donor material in bulk heterojunction solar cells. Recently, chemical defects such as homocouplings have been shown to form at the material synthesis stage, severely limiting the short circuit current of organic photovoltaics. Here we show that indeed carbazole homocoupling limits exciton diffusion in PCDTBT. We propose a mechanism that explains the limitation of exciton diffusion caused by high homocoupling concentrations and short chain lengths. Diffusion is limited when either chain length or homocouplings impair the effective conjugation length of the polymer chain.