Multiple Exciton Dynamics in MoS₂ Nanosheet/Poly(methyl methacrylate)/Polyaniline Composites and Nonlinear Optical Properties: Implications for Saturable Absorber Applications

Here, we demonstrate an efficient nanocomposite system for the enhancement of optical properties via a self-assembled 2D nanoarchitecture combined with insulating and conducting polymers. The excitonic properties of the ternary composites consisting of MoS2 nanosheets, poly methyl methacrylate (PMMA), and polyaniline (PANI) (MPP) were tuned by optimizing the concentration of PANI. Their absorption spectra revealed a strong excitonic coupling between the components. The mechanisms of exciton dissociation and generation of interlayer excitons were investigated by steady-state and transient photoluminescence spectroscopy. The exciton decay time is reduced by almost 95% in the ternary composite at an optimized concentration of PANI than in pure MoS2. This indicates a fast excitonic interaction between MoS2 and PANI in the presence of the insulating polymer PMMA. Furthermore, nonlinear optical studies using the z-scan technique further confirmed the exciton–exciton coupling in the ternary composites. Therefore, these ternary composites having multiple excitons and strong saturable absorption (SA) behavior provide a perspective for next-generation saturable absorber devices and other optoelectronic applications.