High-energy conversion-efficiency direct-alternating-current hybrid generator with piezoelectric polylactide and dynamic Schottky diode

In this paper, a direct alternating current hybrid generator is proposed through the combination of piezoelectric hydroxyapatite (HA)/polylactide (PLLA) composite film with a graphene/silicon dynamic Schottky diode. The proposed hybrid generator provides an overall energy conversion efficiency of 65% under a single mechanical force. This percentage marks the highest efficiency compared with previously reported piezoelectric generators and dynamic Schottky diode generators. The primary mechanisms of the proposed generator are the built-in electric field separation of the diffusion of carriers in the moving Schottky diode, and the synergistic effect of the hydrogen bond and dipole interactions between HA and PLLA for the direct and alternating part of the proposed HA/PLLA/graphene/silicon hybrid generator, respectively. Moreover, the hybrid generator provides a maximum output voltage of 4.7 V for the alternating output and current of 2.9 μA for the direct output, which can simultaneously illuminate several LEDs. Thus, the proposed generator shows great potential in practical applications for converting mechanical energy for self-powered systems or wearable energy sources.