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Heterojunction nanohybrids based on low-dimension semiconductors, including colloidal quantum dots (QDs) and 2D atomic materials (graphene, transition metal chalcogenides, etc) provide a fascinating platform to design of new photonic and optoelectronic devices that take advantages of the enhanced light-solid interaction attributed to their strong quantum confinement and superior charge mobility for uncooled photodetectors with a high gain up to 1010. In these heterojunction nanohybrids, the van der Waals (vdW) interface plays a critical role in controlling the optoelectronic process including exciton dissociation by the interface built-in field that drives the follow-up charge injection and transport to graphene. In this paper, we present our recent progress in development of such heterostructures nanohybrids for uncooled infrared detectors including PbS and FeS2 QDs/graphene and 2D vdW heterostructures MoTe2/Graphene/SnS2 and GaTe/InSe. We have found that nonstoichiometric Fe1–xS2 QDs (x = 0.01–0.107) with strong localized surface plasmonic resonance (LSPR) can have much enhanced absorption in broadband from ultraviolet to short-wave infrared (SWIR, 1–3 μm). Consequently, the LSPR Fe1–xS2 QDs/graphene heterostructure photodetectors exhibit extraordinary photoresponsivity in exceeding 4.32 ×106 A/W and figure-of-merit detectivity D* < 7.50 ×1012 Jones in the broadband of UV–Vis–SWIR at room temperature. The 2D vdW heterostructures allows novel designs of interface band alignments with uncooled NIR-SWIR D* up to 1012 Jones. These results illustrate that the heterostructure nanohybrids provide a promising pathway for low-cost, printable and flexible infrared detectors and imaging systems.
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Probing the Critical Role of Interfaces for Superior Performance in PbS Quantum Dot/Graphene Nanohybrid Broadband Photodetectors
Colloidal quantum dots/graphene (QD/Gr) nanohybrids have been studied intensively for photodetection in a broadband spectrum including ultraviolet, visible, near-infrared, and shortwave infrared (UV−vis-NIR-SWIR). Since the optoelectronic process in the QD/Gr nanohybrid relies on the photogenerated charge carrier transfer from QDs to graphene, understanding the role of the QD−QD and QD−Gr interfaces is imperative to the QD/Gr nanohybrid photodetection. Herein, a systematic study is carried out to probe the effect of these interfaces on the noise, photoresponse, and specific detectivity in the UV−vis-NIR-SWIR spectrum. Interestingly, the photoresponse has been found to be negligible without a 3-mercaptopropionic acid (MPA) ligand exchange, moderate with a single ligand exchange after all QD layers are deposited on graphene, and maximum if it is performed after each QD layer deposition up to five layers of total QD thickness of 260−280 nm. Furthermore, exposure of graphene to C-band UV (UVC) for a short period of 4−5 min before QD deposition leads to improved photoresponse via removal of polar molecules at the QD/Gr interface. With the combination of the MPA ligand exchange and UVC exposure, optimal optoelectronic properties can be obtained on the PbS QD/Gr nanohybrids with high specific detectivity up to 2.6 × 1011, 1.5 × 1011, 5 × 1010, and 1.9 × 109 Jones at 400, 550, 1000, and 1700 nm, respectively, making the nanohybrids promising for broadband photodetection.
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- PAR ID:
- 10521255
- Publisher / Repository:
- ACS
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- ISSN:
- 1944-8244
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acsami.4c01115
