Nanomaterials - 06

Abstract

Soft materials with flexibility, stretchability, and deformability are essential for fabricating wearable electronic devices that are light, thin, and perform well, such as mechanoelectric generators. In recent years, alkyl-π liquids, which consist of a functional π-conjugated unit with bulky yet flexible branched alkyl chains, have attracted attention as a new type of liquid electret material[1] (1, Fig.1). Previous study by our research group has revealed that sufficient coverage ofthe π-conjugated unit with side chains is essential for maintaining electrostatic charges for a more extended time[2]. However, the correlation between the π unit of alkyl-π liquids and their charging properties has not yet been clarified. Herein, we focus on the inherent properties of the π unit of alkyl-π liquids, such as the ionization potential, electron affinity, and polarizability, and clarify the correlations leading to high-performance alkyl-π liquid electret materials.
We employed molecules with methoxy groups instead of branched alkyl chains to calculate the intrinsic electronic parameters of the π unit by DFT calculations and to study the correlation between the parameters and the charge amount of the corona-charged alkyl-π liquids. Based on the results of the above efforts, we designed a new alkyl-π liquid molecule with contorted-hexabenzocoronene (c-HBC) as the π-unit (2, Fig. 1) and evaluated its electret properties. The charge amount of c-HBC liquid follows the correlation we explored. These results provide a molecular design strategy for realizing high-performance alkyl-π liquid electret materials.