Tailoring optical properties of MoS ₂ nanosheets for advanced optoelectronic applications

Interplay between two-dimensional transition metal dichalcogenides such as MoS₂ and organic dye molecules has recently evolved as a fertile platform, offering a pathway to substantiate photovoltaic and optoelectronic device performance. This paper highlights the modulation of optical and excitonic properties of liquid-exfoliated MoS₂ nanosheets via non-covalent functionalisation with two organic dyes, zinc tetraphenylporphyrin (ZnTPP) and Coumarin 6. The UV/Vis absorption and photoluminescence (PL) studies reveal pronounced spectral shifts and significant PL quenching in MoS₂-dye heterostructures, indicating strong electronic coupling and interfacial interactions. While femtosecond transient absorption spectroscopy further elucidates the ultrafast carrier dynamics, demonstrating accelerated exciton relaxation and efficient charge transfer processes in both MoS₂-ZnTPP and MoS₂-Coumarin systems. Notably, the heterostructures exhibit modified exciton populations and reduced carrier lifetimes compared to pristine MoS₂, confirming energy transfer through nonradiative pathways. These findings provide mechanistic insights into the photophysical behaviour of MoS₂-dye hybrids, which may pave the way for energy-efficient, high-performing optoelectronic devices.