Layer-number-dependent photoswitchability in 2D MoS₂-diarylethene hybrids

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Molybdenum disulfide (MoS₂) is a 2D transition metal dichalcogenide (TMD) with significant potential in nanoelectronics and optoelectronics.
• Understanding and controlling the layer-dependent properties of MoS₂ is crucial for its application development.
• Photochromic molecules offer a pathway to dynamically modulate material properties.

Purpose of the Study:

• To investigate the photo-modulation of MoS₂ flakes using diarylethene (DAE) molecules.
• To elucidate the layer-number-dependent charge transfer behaviors in MoS₂-DAE hybrid structures.
• To explore the potential for developing photoswitchable devices based on these hybrids.

Main Methods:

• Fabrication of MoS₂-DAE hybrid structures by functionalizing MoS₂ flakes with DAE molecules.
• Photoisomerization of DAE using UV and visible light to switch between closed and open forms.
• Characterization of photoluminescence (PL) and electric conductivity of the hybrid structures.
• Density Functional Theory (DFT) calculations to understand charge transfer mechanisms.

Main Results:

• Closed-form DAE quenched the PL of monolayer MoS₂, with full recovery upon isomerization to the open-form.
• Electric conductivity of monolayer MoS₂ was significantly enhanced by closed-form DAE isomers.
• No significant modulation of properties was observed for MoS₂ bilayers and trilayers.
• DFT calculations confirmed hole transfer from monolayer MoS₂ to closed-form DAE, explaining the observed effects.

Conclusions:

• The study demonstrates layer-dependent photo-modulation of MoS₂ properties via DAE functionalization.
• Charge transfer interactions are critical for modulating monolayer MoS₂ but are negligible in thicker MoS₂ flakes.
• These findings provide insights for designing advanced photoswitchable nanoelectronic and optoelectronic devices.