Printable Nanocomposite FeS₂–PbS Nanocrystals/Graphene Heterojunction Photodetectors for Broadband Photodetection

Abstract

Colloidal nanocrystals are attractive materials for optoelectronics applications because they offer a compelling combination of low-cost solution processing, printability, and spectral tunability through the quantum dot size effect. Here we explore a novel nanocomposite photosensitizer consisting of colloidal nanocrystals of FeS and PbS with complementary optical and microstructural properties for broadband photodetection. Using a newly developed ligand exchange to achieve high-efficiency charge transfer across the nanocomposite FeS-PbS sensitizer and graphene on the FeS-PbS/graphene photoconductors, an extraordinary photoresponsivity in exceeding ∼10 A/W was obtained in an ultrabroad spectrum of ultraviolet (UV)-visible-near-infrared (NIR). This is in contrast to the nearly 3 orders of magnitude reduction of the photoresponsivity from ∼10 A/W at UV to 10 A/W at NIR on their counterpart of FeS/graphene detectors. This illustrates the combined advantages of the nanocomposite sensitizers and the high charge mobility in FeS-PbS/graphene van der Waals heterostructures for nanohybrid optoelectronics with high performance, low cost, and scalability for commercialization.

Recent Progress of Heterojunction Ultraviolet Photodetectors: Materials, Integrations, and Applications

“…The hybrid vdWs heterostructures combine UV photosensitivity and high carrier mobility, and a promoted UV detection (usually broadband spectral response) is achieved. For example, ZnO QDs are printed on graphene and generated a 2D‐0D hybrid vdWs heterostructure with ultrasensitive detection of UV light,146 and other nanocrystals like FeS 2 ‐PbS149 and FeS 2 150 are utilized to similarly strengthen the light absorption in other reports. Apart from the 2D‐0D hybrid vdWs structures, 2D‐0D hybrid structures based on bulk semiconductor crystals are also reported.…”

Interlayer Transition in a vdW Heterostructure toward Ultrahigh Detectivity Shortwave Infrared Photodetectors

“…[1][2][3][4] Conventional SWIR photodetectors rely on HgCdTe or InAs/GaSb type-II superlattices and InGaAs/GaAsSb type-II quantum wells, which encounter some fundamental obstacles. [1,[5][6][7] For example, the conventional HgCdTe with bandgaps tunable by the ternary chemical compositions suffers from raw material toxicity, poor material uniformity, and low yield. In addition, the HgCdTe SWIR photodetectors, similar like other SWIR photodetectors based on conventional narrowband semiconductors, must operate at cryogenic temperatures to suppress the dark current or thermal noise to ensure high detectivity.…”

Nanocrystalline Pyrite for Photovoltaic Applications

“…achieved an extraordinary photo‐responsivity in exceeding ∼10 6 A/W in nanocomposite FeS 2 −PbS/graphene sensitizer photoconductors in an ultrabroad spectrum of ultraviolet (UV)‐visible‐near‐infrared (NIR). These heterostructures have applications in various devices like nanohybrid optoelectronics with high performance, low cost, and scalability for commercialization …”