Interfacial charge transfers and ultrafast nonlinear optical response via constructing electronic structure-induced MoS2/ZnO heterostructure

The molybdenum disulfide (MoS2) and ZnO composite system have reported as micro-nano photonic crystals in integrated optics. Based on interface engineering, their tunable nonlinear absorption (NLA) and photoelectric characteristics offer a flexible design strategies for saturation absorber and optical limiters. Nevertheless, the mechanism leading to the tunable NLA behavior has not been clearly elucidated, which were attribute to complex charge transfers and carrier regulation characteristics. In this article, MoS2/ZnO heterostructures with excellent nonlinear properties composed of ZnO nanorods (NRs) wrapped with MoS2 nanosheets were prepared by magnetron sputtering (MS) synthesis of MoS2 on highly stacked ZnO NRs. The MoS2/ZnO heterostructures exhibit an interesting brush-like morphology with abundant heterointerfaces base on optimizing sputtering time and temperature, which was beneficial to provide efficient charge transfer pathways. Due to the uneven distribution of the lowest nucleation free energy, MoS2 nanosheets possess a hybrid mode of parallel (C//) and perpendicular orientations (C) on surface of ZnO NRs, which tends to form the bending and vertical growth of layered MoS2 nanosheets. From electron-photon coupling effect, MoS2 nanosheets, ZnO NRs and MoS2/ZnO heterostructures possess favorable saturation absorption (SA), reverse saturation absorption (RSA) and coexisting absorption behavior, respectively. In addition, a changeover from RSA to SA could be realized in MoS2/ZnO heterostructures by increasing the sputtering time. The NLA coefficient of MoS2/ZnO heterostructures are in the order of 10-10 cm/W, which are about 2 times larger than those of the ZnO NRs. Thus, the MoS2/ZnO heterostructures with excellent NLA properties will be promising candidates in optoelectronic devices.(C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this article, MoS2/ZnO heterostructures with excellent nonlinear properties were prepared by interface engineering. The tunable nonlinear absorption behavior was attributed to complex charge transfers and carrier regulation characteristics. MoS2 nanosheets, ZnO nanorods, and MoS2/ZnO heterostructures exhibited saturation absorption, reverse saturation absorption, and coexisting absorption behavior, respectively.