Enhancement of the Seebeck Coefficient of Organic Thermoelectric Materials via Energy Filtering of Charge Carriers

Abstract

Recently, organic materials emerged as the next-generation thermoelectric (TE) materials because of their unique advantages including low cost, high mechanical flexibility, low or no toxicity and low intrinsic thermal conductivity over inorganic TE materials. However, the Seebeck coefficient of organic materials with high TE properties is remarkably lower than that of the inorganic counterparts. It is of significance to improve their Seebeck coefficient and thus the overall TE properties. A high-performance TE material should have high Seebeck coefficient and high conductivity, but there is a trade-off relationship between these two parameters. Lowering the charge carrier concentration can increase the Seebeck coefficient while decrease the conductivity. A remedy is to adopt energy filtering that can remarkably increase the Seebeck coefficient while only slightly lower the conductivity. In this article, we review the energy filtering methods to enhance the Seebeck coefficient and thus the power factor of organic TE materials, including the composite formation with inorganic TE nanomaterials or carbon nanomaterials, composition formation of p-type and n-type materials, and surface energy filtering induced by the dipole moment or ion accumulations. Finally, a

Flexible, scalable, and efficient thermoelectric touch detector based on PDMS and graphite flakes

“…These S values are in accordance with previous published results 23 where a similar value (+18 µV K −1 ) was described for bulk graphite samples. The slightly S decrement from 18 µV K −1 to 14 µV K −1 [25] alongside with the σ increment is once again a well-known trade off due to the existence of more carriers [26,27]. Evaluating these graphite percentage-dependent properties we conclude that there is a Power Factor, PF, enhancement (purple triangles), from 0.19 to 3.8 nW (m.K 2 ) −1 for G Flakes wt% from 40 to 50, respectively.…”

Substrate Modification for High‐Performance Thermoelectric Materials and Generators Based on Polymer and Carbon Nanotube Composite

“…[ 27 ] This phenomena could be also interpreted by energy filtration effect at the interface of PCDTPT and SWCNT. [ 35 ] The polymer composite film on the unmodified substrate exhibit the lower Seebeck coefficient due to its relatively high carrier concentration; while the polymer composite film on CH 3 ‐SAM show a higher Seebeck coefficient because of its relatively low carrier concentration. It is worth noting that the composite film on NH 2 ‐SAM achieves the highest Seebeck coefficient than that on other substrates, presumably because of its lower carrier concentration by electron transferring from the lone‐pair electrons in amino group of NH 2 ‐SAM to the polymer composites.…”

Organic Thermoelectric Materials: Niche Harvester of Thermal Energy

“…[ 218 ] The energy filtering of charge carriers aims to enhance the S of the materials, but its application will bring certain limitations. [ 219 ] Modulating the S and σ through energy filtering methods have an abnormal dependence on the charge carrier concentration. Thus it needs further investigation in detail.…”