Synergistic contribution of flexoelectricity and piezoelectricity towards a stretchable robust nanogenerator for wearable electronics

The fabrication of a high-performance piezoelectric nanogenerator (PENG) with high stretchability and durability is desirable for the next-generation of stretchable and wearable electronics. Herein, an eco-friendly and stretchable flexoelectricity-enhanced piezoelectric nanogenerator (F-PENG) based on zinc-aluminum layered double hydroxide nanosheets (ZnAl:LDH Ns)-ZnO heterostructure is demonstrated on stretchable polydimethylsiloxane (PDMS) substrates. The vertically-oriented eco-friendly ZnAl:LDH Ns are facilely synthesized by dipping the 10 wt% aluminum-doped zinc oxide (AZO) thin films in deionized (DI) water at room temperature. The enhanced output performance of the F-PENG is demonstrated under tapping, bending, and stretching modes, and is attributed to the synergistic flexoelectric and piezoelectric effects. The achieved maximum output power density of F-PENG under tapping is similar to 2.7 mu W/cm(2). The pressure-sensing capability of the F-PENG is demonstrated by the generated outputs under the three applied modes. In addition, the biomechanical energy harvesting capability of the F-PENG is demonstrated by subjecting it to various biomechanical motions. The FPENG exhibits an excellent mechanical durability in all three modes of operation. The present study not only paves the way towards the facile fabrication of stretchable and high-performance F-PENGs with combined flexoelectric and piezoelectric effects, but also validates a wide range of applications in the next generation of stretchable and wearable electronics.

Automated summary

This study demonstrates an eco-friendly and stretchable flexoelectricity-enhanced piezoelectric nanogenerator based on zinc-aluminum layered double hydroxide nanosheets-ZnO heterostructure, showing enhanced output performance attributed to flexoelectric and piezoelectric effects, with high mechanical durability.