Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 25: Focus Session: Organic-based Hybrid Thermoelectrics II
DS 25.4: Talk
Wednesday, March 18, 2020, 12:30–12:45, CHE 89
Radical Ion Doped Organic Single Crystals for Thermoelectric Applications — •Maximilian Frank1 and Jens Pflaum1,2 — 1Experimental Physics VI, Julius Maximilian University of Würzburg — 2Bavarian Center for Applied Energy Research (ZAE Bayern eV), 97074 Würzburg
The successful application of organic semiconductors in lighting or photovoltaics would not have been possible without doping. Motivated by this, we will deal with the implementation of doped molecular crystals in thermoelectrics (TE) which promise the recovery of substantial amounts of waste heat generated upon primary energy consumption [1]. It is desirable to use materials with large Seebeck coefficient S, high electrical conductivity σ, and low thermal conductivity κ, which can be summarized in the dimensionless figure of merit at given temperature zT = σ S2κ T. In this sense, long-range ordered molecular crystals offer an interesting approach by their low thermal conductivities generic to van-der-Waals bound systems combined with moderate mobilities for electrons and holes. We use high quality polyaromatic single crystals to systematically alter their bandfilling and, thus, their electrical transport properties by electrochemical doping. The variations in electrical conductivity as well as Seebeck coefficient will be discussed as function of doping. The results will be critically evaluated in regard of the independent optimization of the thermoelectric parameters and, thus, of the implementation of doped single crystals and thin films in TE applications.
[1] C. Forman, et al., Renew. Sust. Energ. Rev. 2015, 57, 1568