The characterization of nanostructured samples with at least one restricted dimension like thin films or nanowires is challenging, but important to understand their structure and transport mechanism, and to improve current industrial products and production processes. We report on the 2nd generation of a measurement chip, which allows for a simplified sample preparation process, and the measurement of samples deposited from the liquid phase using techniques like spin coating and drop casting. The new design enables us to apply much higher temperature gradients for the Seebeck coefficient measurement in a shorter time, without influencing the sample holder's temperature distribution. Furthermore, a two membrane correction method for the 3ω thermal conductivity measurement will be presented, which takes the heat loss due to radiation into account and increases the accuracy of the measurement results significantly. Errors caused by different sample compositions, varying sample geometries, and different heat profiles are avoided with the presented measurement method. As a showcase study displaying the validity and accuracy of our platform, we present temperature-dependent measurements of the thermoelectric properties of an 84 nm BiSb thin film and a 15 μm PEDOT:PSS thin film.

Low‐cost, non‐toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n‐type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n‐type organic thermoelectrics to date. An organic mixed ion–electron n‐type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi‐frozen ionic carriers yield a large ionic Seebeck coefficient of −3021 μV K−1, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm−1 at 60% relative humidity. The overall power factor is remarkably high (165 μW m−1 K−2), with a ZT = 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi‐constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.

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Abstract

The temperature and thickness dependent thermoelectric properties of Bi 87 Sb 13 nano-films with a thickness from 84 nm to 282 nm have been studied in a temperature range from 110 K up to 450 K. The films have been prepared by thermal evaporation of the raw material from an Al 2 O 3 coated tungsten boat under vacuum conditions of at least 10 −6 mbar. The measurements have been performed using a novel measurement platform, which allows the nearly simultaneous characterization of the thermal conductivity, electrical conductivity, the Seebeck coefficient and the Hall coefficient. All properties are measured in the in-plane direction at the same sample within one measurement run, avoiding many sources of uncertainties and allowing the calculation of the direction dependent, in-plane thermoelectric figure of Merit ZT with high precision. The maximum ZT value of 0.28 has been obtained for the thickest sample at a temperature of 265 K. All comparative measurements have been performed after an initial thermal annealing step, as the heat treatment shows a strong impact on the thermoelectric performance of the films.