Twisted MoSe₂ Homobilayer Behaving as a Heterobilayer

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition-metal dichalcogenide (TMD) heterostructures (HSs) are promising for advanced optoelectronics.
• Artificially twisted HSs offer tunable optical and electronic properties.
• Understanding interlayer interactions is key to controlling material behavior.

Purpose of the Study:

• To investigate energy transfer (ET) in twisted molybdenum diselenide (MoSe2) homobilayers without charge-blocking interlayers.
• To explore the role of dipolar interaction in governing ET.
• To understand how ET influences carrier recombination and photoluminescence.

Main Methods:

• Fabrication of a twisted MoSe2 homobilayer with a large twist angle (~57°) using chemical vapor deposition (CVD) and mechanical exfoliation (Exf.).
• Utilizing lattice parameter mismatch and differing bandgap natures (indirect/direct) of stacked layers.
• Employing experimental and theoretical analyses to study the energy transfer process.

Main Results:

• Demonstrated efficient energy transfer (ET) governed by dipolar interaction in the twisted MoSe2 homobilayer.
• Observed a massive enhancement in photoluminescence (PL) attributed to efficient ET.
• Showed that ET controls carrier recombination channels, weakening interlayer charge transfer.

Conclusions:

• Electronically decoupled MoSe2 homobilayers can be coupled via efficient energy transfer.
• This ET process effectively mimics the behavior of a "true" heterobilayer.
• Twisted homobilayers offer a novel platform for optoelectronic applications by controlling energy transfer pathways.