Photoinduced Interfacial Charge Transfer Tailors Second-Harmonic Generation in NbSe<sub>2</sub>-MoS<sub>2</sub> Heterostructures.
basic_science · Level V
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- Record sourced from PubMed, PMID 41618904.
- Also identified by DOI 10.1021/acs.nanolett.5c05520.
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Abstract
Effective modulation of ultrafast nonlinear optical properties in two-dimensional materials is essential for advancing nanophotonic technologies. In this work, we demonstrate precise control over the ultrafast carrier dynamics in NbSe<sub>2</sub> by tailoring the nanosheet thickness and constructing a van der Waals heterostructure with MoS<sub>2</sub>. Transient absorption measurements reveal that carrier lifetimes extend from several to hundreds of picoseconds with increasing layer thickness, due to interlayer coupling. More importantly, interfacial charge transfer from MoS<sub>2</sub> to NbSe<sub>2</sub> in the heterostructure further prolongs carrier relaxation and significantly enhances the second harmonic generation (SHG) response. First-principles calculations attribute this SHG enhancement to a symmetry-breaking electronic imbalance induced by charge redistribution at the interface. These findings establish interfacial charge engineering as a powerful and general strategy for tailoring ultrafast nonlinear optical properties in 2D materials, offering new pathways for designing high-performance optoelectronic devices.