Performance Modulation on MgZnO/ZnO Heterojunction Flexible UV Photodetector by Piezophototronic Effect

It is essential to modulate materials and their interfaces for excellent device performance. Here, an ultraviolet (UV) photodetector (PD) based on a flexible polyethylene terephthalate (PET)/ZnO/MgZnO heterojunction was successfully fabricated at room temperature. The piezophototronic effect was first used to modulate the transport behavior of the photogenerated carriers at the interface of the MgZnO/ZnO heterojunction. The responsivity increased from 0.23 to 0.95 A W−1 with the increase in external tensile strain from 0 to 0.18, an increase of ∼313%. Meanwhile, with the decrease in external compressive strain from 0 to −0.18, the responsivity decreased by ∼63%. This is owing to the modulation of the junction barrier and photogenerated carrier transport behavior at the MgZnO/ZnO junctions/interfaces via the piezophototronic effect. Moreover, the PD maintained excellent mechanical stability and reproducibility after different bending cycles 0/50/100/150/200 and excellent environmental stability after storage for over two months, which are beneficial for its practical applications. Furthermore, this study developed a method for modulating the performance of UV PDs, and showed that the piezophototronic effect has important theoretical significance and application prospect for the modulation of heterojunction interfaces.