In the rapidly advancing field of optoelectronics, self-powered near-infrared (NIR) photodetectors are gaining attention for applications in imaging, environmental monitoring, and optical communication. Recently, a research team from Shandong University led by Professor Zai-xing Yang has made a significant leap forward by constructing a novel mixed-dimensional heterojunction between GaSb nanowires (NWs) and Bi₂O₂Se nanosheets (NSs). This breakthrough device demonstrates ultralow dark current, ultrafast response, and multifunctional capabilities — all without an external power supply.

Why This Research Matters

• Record-Low Dark Current: The GaSb/Bi₂O₂Se NW/NS and NW array/NS devices achieve ultralow dark currents of 0.07 pA and 0.08 pA, respectively, enabling exceptionally clean signal detection.
• Ultrafast Response: Response times of < 2 ms (single NW/NS) and 6/4 ms (NW array/NS) outperform most comparable systems, crucial for high-speed data processing.
• Broadband Sensitivity: Effective photodetection from visible to 1310 nm wavelengths makes these devices versatile for diverse NIR applications.
• Integrated Functionality: Beyond detection, the devices successfully demonstrated self-powered imaging and optical data transmission.

Innovative Design and Mechanisms

• Mixed-Dimensional Type-II Heterojunction: Combining 1D GaSb NWs and 2D Bi₂O₂Se NSs yields a built-in electric field (~140 meV) that promotes rapid, bias-free separation of photo-generated carriers.
• Array Architecture for Enhanced Performance: Ordered NW arrays, fabricated via contact printing, provide larger active areas, stronger photocurrents, and improved Ilight/Idark ratios.
• Interface Characterization: Advanced tools such as Kelvin probe force microscopy (KPFM), XRD, and AFM confirm precise band alignment and high-quality heterointerfaces.

Applications and Future Outlook

• Imaging: The team demonstrated single-pixel imaging of a “panda” highlighting potential for compact NIR cameras.
• Photocommunication: Successful ASCII code transmission (“HAPPY”) proves feasibility for secure, high-speed optical links.
• Next Steps: Scaling up fabrication, integrating with flexible substrates, and exploring other material pairings could open new pathways for wearable sensors, IoT devices, and space-borne imaging systems.

Stay tuned for more exciting developments from Prof. Yang’s group as they continue redefining the boundaries of self-powered optoelectronics and NIR photodetection technology.