Highly sensitive piezo-gated bilayer thin-film transistors with all operation mode switching via the synergistic effect of ZnO and porous PVDF-TrFE

Abstract

Flexible and wearable electronics are attracting growing interest for next-generation electronic devices, with the piezoelectric and ferroelectric copolymer PVDF-TrFE widely studied for its high piezoelectricity and mechanical flexibility. The piezoelectric performance of PVDF-TrFE, serving as the gating material, was enhanced by creating a porous structure via wet etching of embedded ZnO nanoparticles, followed by corona poling for dipole alignment and stable remanent polarization. ZnO thin films were then deposited on PVDF-TrFE to act as the semiconducting piezo-channel in piezo-gated thin-film transistors (PGTFTs). When compressive forces were applied to the negatively poled surface, the induced piezopotential promoted electron accumulation at the ZnO top surface, thereby resulting in increased output current. In contrast, the positively poled surface led to electron depletion and reduced conductance under the same mechanical stresses. With longer poling durations, positively poled devices exhibited inversion mode, showing that the piezopotential can modulate carrier distribution and even reverse the dominant carrier type in the channel. The synergistic coupling of ZnO and PVDF-TrFE piezoelectric fields enabled PGTFTs to reach remarkable gauge factors of 32 481.2, −31 163.9, and 69 597.5 in accumulation, depletion, and inversion modes, respectively, demonstrating the feasibility of piezo-gating for controlling charge transport in semiconductors and enabling highly sensitive, self-powered, flexible electronics.