Modification of the Exciton Lifetime and Saturable Absorption Behavior of ZnO@MoS₂/Polyaniline Nanocomposite Films

Engineering the dynamics of excitons, including charge generation, diffusion, and recombination in semiconductor–polymer nanocomposites, provides a powerful platform for fundamental and applied interests in linear and nonlinear optics. In this work, we have reported the modulation and generation of multiple excitons in ternary composite consisting of core–shell ZnO@MoS2 heterostructures and fibrous polyaniline (PANI). The investigation of nonlinear optical properties of MoS2-based nanocomposite films shows that pure MoS2 thin films show typical saturable absorption (SA) behavior while a crossover from SA to reverse saturable absorption (RSA) occurs for ZnO@MoS2 binary composites. Interestingly, after the addition of conducting polymer PANI, the ternary composite thin films again exhibit an SA response. Particularly, the Pauli blocking effect induces SA in MoS2, whereas the nonlinear response in the ternary composites can be attributed to the hybridization of multiple excitons. Therefore, our findings, which reveal the role of engineered excitonic behavior, can offer several opportunities for multifunctional photonic devices.