An enhanced Vis-NIR photodetector based on Ag@ PbS core-shell plasmonic heterostructure

Highlights: • A broadband photodetector based on Ag@PbS was fabricated by DC sputtering and wet chemical methods. • TEM, EDS and XRD analyses provided clear evidence of core-shell structure formation. • Device exhibits fast speed, high responsivity, outstanding D∗, large EQE and long-term stability. • Intimate interface between the Ag core and PbS shell facilitate carriers injection and transport. • Excellent performance can be attributed to the Schottky barrier formation and Ag LSPR effect. -- Abstract: Embedding plasmonic metal nanostructures into the semiconductor materials offers a new route to enhance the performance of photodetectors. Herein, we have reported the development of a high-performance broadband photodetector based on a new core-shell nanostructure, termed Ag@PbS, where Ag nanoparticle cores were synthesized by DC sputtering technique and subsequently coated by PbS shell using a convenient wet chemical method. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses provide clear evidence of core-shell heterostructure formation. Close interfacial contact and Schottky barrier formation efficiently boost separation and transfer of photogenerated charge carriers across the interface of the core and shell. Moreover, the presence of Ag cores promotes photodetecting performance through the strong light absorption and scattering, abundant hot hole carriers injection and plasmonic energy transfer. Therefore, the photoconductive device delivered a broadband response range from visible to near-infrared with a maximum responsivity of 26.1 A W⁻¹, a specific detectivity of 1.8 × 10¹³ Jones and EQE of 4013% under 808 nm laser illumination at low light intensity (∼ 0.14 mW cm⁻²). Importantly, the device exhibits a fast response time of 170 ms along with excellent operational reliability and long-term stability in the ambient air atmosphere. Such a result sheds new light on the design and development of novel core-shell nanostructures with advanced optoelectronic properties.