Berlin 2024 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 18: Organic Electronics and Photovoltaics I
CPP 18.6: Vortrag
Dienstag, 19. März 2024, 11:00–11:15, H 0110
Doping gradients optimize the thermoelectric power factor of a conjugated polymer — •Dorothea Scheunemann1, Jian Liu2,3, Mariavittoria Craighero3, Vandna Gupta3, Sri Harish Kumar Paleti3, Emmy Järsvall3, Youngseok Kim3, Kai Xu4, Juan Sebastián Reparaz4, L. Jan Anton Koster5, Mariano Campoy-Quiles4, Martijn Kemerink1, Anna Martinelli3, and Christian Müller3 — 1Heidelberg University, Germany — 2Chinese Academy of Sciences, China — 3Chalmers University of Technology, Sweden — 4Materials Science Institute of Barcelona, Spain — 5University of Groningen, The Netherlands
Functionally graded materials (FGMs) that feature continuous changes in doping level have been considered as a tool to improve the overall thermoelectric performance of inorganic semiconductors. For organic semiconductors this method has been little used so far. However, since the conductivity σ and the thermopower α vary strongly with the doping level, it can be assumed that a doping gradient also influences the power factor α2σ. Here, we show that even moderate electric fields can generate lateral doping gradients in polymer films doped with F4TCNQ, with suitable gradients achieving up to 8-fold enhancement in power factor. Kinetic Monte Carlo simulations enabled us to understand under which conditions a doping gradient can result in an increase in power factor. Our findings indicate that the FGM concept is (i) a way to improve the thermoelectric performance of not yet optimally doped organic semiconductors, (ii) facilitates the screening of different polymer:dopant pairs as a thermoelectric material.
Keywords: organic thermoelectrics; conjugated polymer; chemical doping