Polar Organic Charge-Transfer Complex of the Asymmetrical Component for Flexible Piezoelectric Energy Harvesting and Self-Powered Wearable Sensors
Shuang Ma, Zhiqi Liu, Chenchen Gao, Huang Lin, Wenxin Xiang, Jinqiu Chen, Shuai Wang, Rui Li, Wenbo Mi, Zebin Li, Yang Yu, Jing Zhang, Benlin Hu, Yannan Xie
Abstract
Organic piezomaterials have attracted much attention because of their easy processing, lightweight, and mechanic flexibility properties. Developing new smart organic piezomaterials is highly required for new-generation electronic applications. Here, we found a novel organic piezomaterial of organic charge-transfer complex (CTC) consisting of dibenzcarbazole analogue (DBCz) and tetracyanoquinodimethane (TCNQ) in the molecular-level heterojunction stacking mode. The DBCz–TCNQ complex exhibited ferroelectric properties (the saturated polarization of ∼1.23 μC/cm 2 ) at room temperature with a low coercive field. The noncentrosymmetric alignment ( Pc space group) led to a spontaneous polarization of this architecture and thus was the origin of the piezoelectric behavior. Lateral piezoelectric nanogenerators (PENGs) based on the thermal evaporated CTC thin-film exhibited significant energy conversion behavior under mechanical agitation with a calculated piezoelectric coefficient ( d 31 ) of ∼33 pC/N. Furthermore, such a binary CTC thin-film constructed single-electrode PENG could show steady-state sensing performance to external stimuli as this flexible wearable device precisely detected physiological signals (e.g., finger bending, blink movement, carotid artery, etc.) with a self-powered supply. This work provides that the polar CTCs can act as efficient piezomaterials for flexible energy harvesting, conversion, and wearable sensing devices with a self-powered supply, enabling great potential in healthcare, motion detection, human–machine interfaces, etc.