Epitaxial Growth of PbS Nanocrystals from PbI₂ Nanosheet Templates and Its Application in Fast Near‐Infrared Photodetectors

Abstract Heterostructures of 0D/2D materials synergistically combine the advantages of two different materials, and photodetectors (PDs) based on such heterostructures demonstrate superior detection properties as compared to those based on each individual material. Here, a facile solution method is proposed for the fabrication of 0D/2D heterostructures to overcome the limitations of the traditional chemical vapor deposition method. The 0D PbS nanocrystals (NCs) are epitaxially grown from 2D‐PbI₂ nanosheet templates by a simple wet‐chemical sulfuration process. The resulting heterojunction PDs demonstrate wide detection range up to 2000 nm, a fast photoresponse of ≈400 µs, and a specific detectivity of more than 10¹² Jones. The superior device performances are attributed to the underneath PbI₂ layer, which can not only be used as the precursor layer but also help to passivate the defect states of PbS NCs. More importantly, the developed Structured II device with Au–PbI₂ Schottky contact effect can suppress the dark current of PD to extend its depletion region and improve the response speed. Overall, this study demonstrates a novel strategy for the growth of 0D/2D heterostructures in conjunction with fast near‐infrared detection, which surmount the limitations of photoconductive detectors in terms of large‐scale synthesis and response speed.