Improved piezoelectricity of polylactide using vitamin B₂ for poling-free mechanical and acoustic nanogenerators

In this study, we designed and fabricated a poling-free piezoelectric nanogenerator using bio-based polymer and filler, a poly(l-lactic acid) (PLLA)/vitamin B₂ (VB₂) composite film. The addition of VB₂ to PLLA led to improved crystallinity and enhanced the molecular orientation of PLLA, resulting in a significantly enhanced output performance of the PLLA/VB₂ nanogenerator. The proposed nanogenerator provides a maximum power density of 75.68 mW cm⁻³, which is approximately 28.7 times higher than that of pure PLLA nanogenerator. Moreover, the PLLA/VB₂ nanogenerator exhibits good electrical responses under both mechanical and acoustic stimulations. The collected mechanical energy from the motion of human joints can power up several LEDs. The PLLA/VB₂ nanogenerator can sensitively detect sound frequency from 1 to 27 kHz. Thus, it has great application potential in ambient mechanical and acoustic energy harvesting, wearable devices, and human–machine controlling systems.