Chiral 1D Hybrid Metal Halides with Piezoelectric Energy Harvesting and Sensing Properties

Chiral hybrid metal halides have been widely studied in  the field of photondetectors, chiral optics, and spintronics due to their great structural flexibility and suitable bandgaps. Inspired by such great progress made in the abovementioned fields, continuous efforts need to be paid to seek other interesting applications for  chiral hybrid metal halides. Herein, the synthesis of a pair of one-dimensional enantiomorphic hybrid metal halide piezoelectrics, R/SMPCdCl₄(R/SMP = R/S-2-methylpiperazine), and their applications in piezoelectric energy harvesting and sensing are reported. Density functional theory calculations show that these chiral  piezoeletrics possess low elastic properties and high piezoelectric constants (16.71, 8.39, and 7.35 pC N⁻¹). In addition, devices made of RMPCdCl₄/PDMS (PDMS = polydimethylsiloxane) composite films are fabricated for piezoelectric energy harvesting and sensing. The piezoelectric energy harvesters with optimized content of 15 wt% RMPCdCl₄/PDMS show not only excellent performance with an open-circuit voltage of 2.57 V, short-circuit current of 0.37 μA, and power density of 0.55 μW cm⁻² but also outstanding stability of more than 3500 cycles. Meanwhile, these piezoelectric energy harvesters exhibit prominent sensing properties for detecting tapping, finger bending, walking, and running. It is demonstrated that chiral hybrid metal halides hold great potential in intelligent wearable and sensing devices.