Organic Photo-Responsive Piezoelectric Materials Based on Pyrene Molecules for Flexible Sensors

Abstract

Due to the advantages of multiplicity, functionality, and flexibility of organic building blocks, organic piezoelectric materials are regarded as next-generation materials for potential applications in flexible sensors and energy harvesting devices. Here, a new pure organic pyrene-based molecule, PyPT is presented, which crystallizes in a non-centrosymmetric structure. PyPT is synthesized and demonstrated to be suitable for developing flexible sensors due to its remarkable piezoelectric properties. The pyrene-based piezoelectric molecule exhibits excitation wavelength-dependent emission behavior and aggregation-caused quenching properties and demonstrated a piezoelectric coefficient (d₃₃) of 8.02 ± 0.26 pm V⁻¹. The output electronic signal of a PyPT-based flexible sensor shows a significant increase from 30 to 721 pA as the strain increases from 0.12% to 0.59% with a low Young's modulus of 1.63 Gpa. This high-performance piezoelectric sensor can serve as a sensitive sound sensor for sound detection and recognition based on the basic characteristics of sound, such as amplitude, frequencies, and timbres. This research offers new insights into advancing pure organic luminescent materials with piezoelectric properties, paving the way for applications in flexible electronics for wearables, human–machine interfaces, and the Internet of Things.