Gold Nanorod-Activated Graphene/MoS2 Nanosheet-Based Photodetectors for Bidirectional Photoconductance

Digvijay Singh Tomar, Sandip Ghosh, Li Chi Jhan, Surojit Chattopadhyay*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Graphene and its nanohybrid photodetectors (PDs) offer unique interfacial and synergistic properties in contrast to conventional semiconductor-based PDs. In this work, we compare the performance of identically fabricated PDs based on pure chemical vapor deposition-grown monolayer graphene, demonstrating a positive photoresponse, that exhibits a gain in photoresponsivity (R) with the addition of two-dimensional MoS2 (chemically exfoliated). However, further addition of plasmonic gold nanorods (AuNRs), on the MoS2/graphene PD, results in the flipping of the photoconductivity to negative. The negative photoresponse is explained by an increased dark current via the complex conductive network model and a lower photocurrent due to the photogenerated electron capture by the AuNRs in the AuNRs/MoS2/graphene PD. The contrasting shape and nature of the dynamic photoresponses are modeled using theoretical fitting and explained based on carrier transport in individual components. The highest R in the moderately fast graphene PD device is ∼2 × 104 A W-1 under 808 nm which could be slightly improved to ∼3 × 104 A W-1 by introducing MoS2 nanoflakes, albeit at the cost of the response time which slows down from ∼90 ms (in the former) to 558 ms in the latter. The introduction of AuNRs did speed up the response time in the AuNRs/MoS2/graphene PD to 20.5 ms but produced a strikingly different negative photoresponse attributed to a higher dark current in the material. We proposed a single mechanism to explain the positive and negative photoresponses reported so far for the hybrid PDs.

Original languageEnglish
Pages (from-to)1783-1795
Number of pages13
JournalACS Applied Nano Materials
Issue number3
StatePublished - 10 Feb 2023


  • gold nanorods (AuNRs)
  • graphene
  • hybrid photodetector
  • molybdenum disulfide (MoS)
  • negative photoconductivity (NPC)


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