Enhancing the Performance of N‐Type Thermoelectric Devices via Tuning the Crystallinity of Small Molecule Semiconductors

Abstract

In the development of high‐performance organic thermoelectric devices, n‐type materials, especially with small molecule semiconductors, lags far behind p‐type materials. In this paper, three small molecules are synthesized based on electron‐deficient naphthalene bis‐isatin building blocks bearing different alkyl chains with the terminal functionalized with 3‐ethylrhodanine unit and studied their aggregation and doping mechanism in detail. It is found that crystallinity plays an essential role in tuning the doping behavior of small molecules. Molecules with too strong crystallinity tend to aggregate with each other to form large crystalline domains, which cause significant performance degradation. While molecules with weak crystallinity can tolerate more dopants, most of them exhibit low mobility. By tuning the crystallinity carefully, organic thermoelectric devices based on C12NR can maintain high mobility and realize effective doping simultaneously, and a high power factor of 1.07 µW m −1 K −2 at 100 °C is realized. This delicate molecular design by modulating crystallinity provides a new avenue for realizing high‐performance organic thermoelectric devices.

Molecular perspective and engineering of thermal transport and thermoelectricity in polymers

“…In a recent study by Duan et al , 211 three different polymers with varying side chains were examined: C12NR (C 12 H 25 ), CFNR (C 10 H 20 –C 6 F 13 ), and C16NR (C 16 H 3 ). It was found that C16NR, possessing the longest alkyl chain, exhibited the weakest crystallinity.…”

Synthesis and Brønsted acid doping of solution processable poly(thienylene vinylene) for thermoelectric application

“…S22, † thereby indicating the formation of BCF crystals. The largely unchanged lattice parameters can be attributed to the fact that the less-ordered regions of P3,4EHTV are able to accommodate the extrinsic dopants without disturbing the existing microstructural packing, 64,75,76 thereby achieving host/guest (conjugated polymer/BCF) miscibility. This is further veried by the diiodomethane contact angle measurements in Fig.…”

Aryl-Ethenyl-Substituted Diketopyrrolopyrrole Semiconductors with trans Configuration and Ultraclose π-Plane Stacking Distance

“…Consequently, DPP-based compounds exhibit high hole or electron mobilities. − The introduction of a D–A structure further enhances the environmental stability and boosts the transport ability of the charge carriers. Therefore, DPP-based compounds have found extensive application in organic electronic devices, − such as organic field-effect transistors (OFETs), , organic electrochemical transistors (OECTs), , organic light-emitting diodes (OLEDs), , organic solar cells (OSCs), − organic thermoelectric devices (OTEs), − etc . Particularly, DPP polymers have been used for stretchable electronics, such as stretchable organic thin-film transistor (OTFT) , and OECT, , which are very important research topics in the scientific community.…”