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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Poster III

CPP 28.54: Poster

Wednesday, March 20, 2024, 11:30–13:30, Poster C

Fast on-chip AC Seebeck measurement — •Andreas Waxweiler, Ejona Syla, Clara Wiesner, Morteza Shokrani, and Martijn Kemerink — Institute for Molecular Systems Engineering and Advanced Materials, Heidelberg University, 69120 Heidelberg, Germany

Organic thermoelectric generators (OTEGs) show promise as a renewable energy source for small-scale devices. Despite the growing emphasis on improving the Seebeck coefficient (S) of organic materials, a precise and fast measurement of S of organic thin films appears to be lacking: the common DC method for measuring S involves substantial waiting times and must be repeated for multiple temperature gradients, which makes the measurement slow and prone to errors. To overcome this, we propose a fast, robust and easy-to-calibrate Seebeck coefficient measurement utilizing an alternate current (AC) technique. In this method, an oscillating current (frequency ω) is applied to an on-chip thin film heater. The resulting thermal wave (frequency 2ω) leads to an AC thermovoltage at the same frequency that is measured by lateral electrodes across the chip. The solution of the 1-dimensional heat equation aligns well with the experimentally measured temperatures at the electrodes, allowing us to be independent of temperature measurements by calibrating the system with the heat equation. As a result, our system requires neither an external heater or cooler, nor a temperature sensor. The measurement times can be drastically decreased to less than a minute, using a chip design that can be fabricated by simple thermal evaporation through a shadow mask.

Keywords: Seebeck coefficient; thermoelectric generator; Organic thin films