Facet-engineered (100)-oriented MoO₂ nanoribbons for broadband self-powered photodetection

Abstract

Broadband photodetection plays a vital role in aerospace applications, biomedical imaging, and advanced communication systems. While molybdenum dioxide (MoO2) exhibits exceptional electrical conductivity, carrier mobility, and environmental stability, its potential for photodetection has remained unrealized, with existing literature reporting negligible optoelectronic responses. Here, we unlock latent photoresponsivity of MoO2 by facet engineering, demonstrating that exposing the (100) crystallographic plane activates its intrinsic photoelectric conversion. Using atmospheric-pressure chemical vapor deposition, we successfully fabricated large-area arrays of (100)-oriented MoO2 nanoribbons. The resulting flexible photodetector on polyethylene glycol terephthalate (PET) substrate exhibits unprecedented performance, achieving broadband detection from visible to long-wave infrared (LWIR: 0.5–10.5 µm) range without external bias. The device demonstrates a fivefold enhancement in responsivity compared to rigid substrate configurations, reaching 107.31 mA W−1 at 10.5 µm wavelength with an exceptionally low noise-equivalent power (NEP) of 6.64 pW Hz−0.5, surpassing all self-powered photodetectors reported to date. Comprehensive characterization reveals distinct photoresponse mechanisms: photothermoelectric effects dominate on silicon substrates, while photobolometric behavior prevails in flexible configurations. These findings not only resolve the previously observed photoresponse limitations in MoO2 but also establish facet engineering as a general approach for developing high-performance photodetectors based on metallic oxides, with significant implications for flexible optoelectronic applications.