Performance modulation of ZnO/WSSe heterojunction photodetectors via longitudinal stress bending

Abstract

In the practical application of photodetectors, they are often subjected to external bending forces. To explore the influence of stress bending, this study constructed a novel heterojunction ZnO/WSSe with two configurations: ZnO-Se and ZnO-S. The stability of these heterojunctions was confirmed through calculations of formation energy, phonon spectrum analysis, and AIMD simulations. Electronic property studies revealed different band configurations. ZnO-Se exhibited a type-I heterojunction with a bandgap of 2.18 eV, while ZnO-S formed a type-II heterojunction with a bandgap of 1.88 eV. Despite the same composition, different interface states led to different electrostatic potentials. Optical property analysis indicated that both heterojunctions had enhanced light absorption compared to the intrinsic materials. The heterojunction photodetectors demonstrated significant photocurrent response and exhibited a negative differential resistance effect in their I-V characteristics, indicating different turn-on voltages. Longitudinal stress bending experiments further showed effective modulation of photocurrent response and I-V characteristics, highlighting mechanical stress engineering as a means to enhance performance. In summary, these findings highlight the potential of ZnO-Se and ZnO-S heterojunctions in optoelectronic applications.