Epitaxial Growth of PbS Nanocrystals from PbI_2 Nanosheet Templates and Its Application in Fast Near-Infrared Photodetectors

摘要

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-PbI(2)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 approximate to 400 mu s, and a specific detectivity of more than 10(12)Jones. The superior device performances are attributed to the underneath PbI(2)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-PbI(2)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.