Analysis of molecular shapes and polarity in aniline derivatives for enhanced n-type carbon nanotubes based thermoelectrics and their application in self-powered electronics

Developing cost-effective and high-performance n-type thermoelectric (TE) materials is a significant challenge for their utilization in organic electronics. Clarifying the influence of molecular structure on TE properties is of utmost importance. In this work, the analysis on how the shape and polarity of organic molecules affect the thermoelectric performance of n-type composites based on single-walled carbon nanotubes (SWCNTs) is presented. A variety of aniline derivatives, characterized by low cost, diverse frameworks, tunable polarity, shallow HOMO levels are selected for tuning the n-type TE performance of SWCNTs. Notably, among these derivatives, pphenylenediamine (PDA) with its compact planar structure and optimal polarity (Log P =-0.68), facilitated robust pi-pi interactions with SWCNTs. Additionally, the formation of hydrogen bonds between PDA and the solvent N-Methyl pyrrolidone (NMP) has been confirmed by theoretical calculations and 1H NMR results, further contributing to its superior performance. These interactions yielded a highest power factor of 745.47 +/- 22.51 mu W m- 1 K- 2, ranking among the highest reported for organic molecules/SWCNT materials to date. Taking advantage of its high performance, a TE device was fabricated, which exhibited an impressive temperature resolution of 0.07 K. Furthermore, a self-powered early warning system for battery overheating based on TE devices was firstly developed, which can effectively detect temperature variations in batteries, enabling precise overheating detection and explosion prevention.