Anomalous photovoltaics in Janus MoSSe monolayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Conventional photoelectric devices face efficiency limits due to p-n junction architectures.
• The anomalous photovoltaic effect (APE) in polar crystals offers a potential alternative for enhanced energy conversion.
• Thinning polar materials is crucial for maximizing the depolarization field and improving APE.

Purpose of the Study:

• To demonstrate Janus MoSSe monolayers for efficient spontaneous photocurrent generation.
• To investigate the photoresponsivity, quantum efficiency, and photoresponse time of MoSSe devices.
• To explore scalable methods for enhancing photovoltage in 2D polar materials.

Main Methods:

• Fabrication and characterization of atomically thin Janus MoSSe monolayers (~0.67 nm).
• Measurement of photocurrent generation, photoresponsivity, and external quantum efficiency.
• Investigation of photovoltage scaling by stacking MoSSe layers with varying interlayer configurations.

Main Results:

• Janus MoSSe monolayers exhibited strong spontaneous photocurrent generation.
• Observed photoresponsivity up to 3 mA/W, ~1% external quantum efficiency, and ultrafast photoresponse (~50 ps).
• Photovoltage was successfully scaled up by stacking MoSSe layers without requiring specific interlayer twist angle control.

Conclusions:

• Atomically engineered Janus MoSSe monolayers are effective for spontaneous photocurrent generation.
• The demonstrated MoSSe devices show promising performance for photovoltaic applications.
• This work enables the development of high-performance, flexible, and compact photovoltaics and optoelectronics using Janus polar materials.