Facet-Engineered (100)-Oriented MoO₂ Nanoribbons for Broadband Self-Powered Photodetection

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Molybdenum dioxide (MoO2) possesses excellent electrical and environmental properties but has shown limited photodetection capabilities.
• Existing literature reports negligible optoelectronic responses for MoO2, hindering its application in photodetectors.

Purpose of the Study:

• To investigate and enhance the photoresponsivity of MoO2 through facet engineering.
• To develop high-performance, self-powered broadband photodetectors utilizing engineered MoO2 nanostructures.

Main Methods:

• Fabrication of (100)-oriented MoO2 nanoribbons using atmospheric-pressure chemical vapor deposition.
• Integration of MoO2 nanoribbons onto flexible polyethylene glycol terephthalate (PET) substrates.
• Characterization of photodetector performance across visible to long-wave infrared (LWIR) spectrum.

Main Results:

• Achieved broadband photodetection (0.5-10.5 µm) without external bias.
• Demonstrated a fivefold increase in responsivity on flexible substrates compared to rigid ones, reaching 107.31 mA W⁻¹ at 10.5 µm.
• Obtained a record low noise-equivalent power (NEP) of 6.64 pW Hz⁻⁰·⁵ for self-powered photodetectors.
• Identified distinct photoresponse mechanisms (photothermoelectric vs. photobolometric) dependent on substrate type.

Conclusions:

• Facet engineering, specifically exposing the (100) plane, activates the intrinsic photoelectric conversion in MoO2.
• The developed flexible MoO2 photodetector exhibits superior performance, surpassing existing self-powered devices.
• This work establishes facet engineering as a viable strategy for advancing metallic oxide-based photodetectors for flexible optoelectronics.