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Two-dimensional layered materials have emerged prominently in the past decade, largely being investigated fundamentally and practically. Their unique layered structure and atomic-scale thickness make them attractive with exclusive electrical and optical properties compared to their bulk counterparts. Molybdenum disulfide (MoS2) is the most widely studied material in the family of transition metal dichalcogenides. The direct and variable bandgap, high carrier mobility, thermal and chemical stability makes it an attractive choice for next-generation photodetector applications. MoS2 heterojunction-based photodetectors offer ultrafast charge transfer and broadband photoresponse, adding more functionality beyond their individual counterparts. Enormous efforts have been devoted to adopting a new strategy that can improve photodetector performance in terms of responsivity and response time. This review briefly discusses the photo-induced current mechanism and performance parameters along with some important aspects to realize better device performance. Here, we critically review the current status and progress made towards MoS2-based photodetectors, followed by a discussion on open challenges and opportunities in their future application.

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2D MoS2 holds immense potential for electronic and optoelectronic applications due to its unique characteristics. However, the atomic-scale thickness of MoS2 hinders the optical absorbance, thereby limiting its photodetection capability. Vertically-aligned MoS2 (VA-MoS2) has an advantange of strong optical absorption and quick intra-layer transport, offering high speed operation. The coupling of plasmonic metal nanostructure with MoS2 can further enhance the light-matter interaction. Pt/Pd (as opposed to Ag/Au) are more promising to design next-generation nano-plasmonic devices due to their intense interband activity over a broad spectral range. Herein, we report Pt nanoparticle (NPs) enhanced broadband photoresponse in VA-MoS2. The optical absorbance of MoS2 is enhanced after the integration of Pt NPs, with a four-fold enhancement in photocurrent. The formation of Schottky junction at Pt-MoS2 interface inhibits electron transmission, suppressing the dark current and substantially reducing NEP. The plasmonic-enabled photodetector shows enhanced responsivity (432 AW-1, 800 nm) and detectivity (1.85 × 1014 Jones, 5 V) with a low response time (87 ms /84 ms), attributed to faster carrier transport. Additionally, a theoretical approach is adopted to calculate wavelength-dependent responsivity, which matches well with experimental results. These findings offer a facile approach to modulate the performance of next-generation optoelectronic devices for practical applications.

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