Enhancing Quantum Yield in Strained MoS₂ Bilayers by Morphology-Controlled Plasmonic Nanostructures toward Superior Photodetectors

Abstract

Recently, extracting hot electrons from plasmonic nanostructures and utilizing them to enhance the optical quantum yield of two-dimensional transition-metal dichalcogenides (TMDs) have been topics of interest in the field of optoelectronic device applications, such as solar cells, light-emitting diodes, photodetectors, and so on. The coupling of plasmonic nanostructures with nanolayers of TMDs depends on the optical properties of the plasmonic materials, including radiation pattern, resonance strength, and hot electron injection efficiency. Herein, we demonstrate the augmented photodetection of a large-scale, transfer-free bilayer MoS2 by decorating this TMD with four different morphology-controlled plasmonic nanoparticles. This approach allows engineering the band gap of the bilayer MoS2 due to localized strain that stems up from plasmonic nanoparticles. In particular, the plasmonic strain blue shifts the band gap of bilayer MoS2 with 32 times enhanced photoresponse demonstrating immense hot electron injection. Besides, we observed the varied photoresponse of MoS2 bilayer hybridized with different morphology-controlled plasmonic nanostructures. Although hot electron injection was a substantial factor for photocurrent enhancement in hybrid plasmonic semiconductor devices, our investigations further show that other key factors such as highly directional plasmonic modes, high-aspect-ratio plasmonic nanostructures, and plasmonic strain-induced beneficial band structure modifications were crucial parameters for effective coupling of plasmons with excitons. As a result, our study sheds light on designing highly tailorable plasmonic nanoparticle-integrated transition-metal dichalcogenide-based optoelectronic devices.

An Ultrasensitive Gateless Photodetector Based on the 2D Bilayer MoS2–1D Si Nanowire–0D Ag Nanoparticle Hybrid Structure

“…Photoresponsivity is seven orders of magnitude higher than the case of MoS 2 on sapphire, as detailed and discussed in Figure S9. The gateless responsivity is ∼500,000 times higher than the previously reported similar plasmonic-enhanced bilayer MoS 2 gateless device . Moreover, photoresponsivity is ∼4 times higher under green light than red and blue light.…”

“…The gateless responsivity is ∼500,000 times higher than the previously reported similar plasmonic-enhanced bilayer MoS 2 gateless device. 46 Moreover, photoresponsivity is ∼4 times higher under green light than red and blue light. This is because LSPR is designed to be maximized at green incident light, where field enhancement is strongest.…”

Photocurrent Enhancement of PtSe2 Photodetectors by Using Au Nanorods

“…The photocurrent in 5 nM Au-nanorod-coated 2D PtSe2 is approximately fivefold higher than that in bare 2D PtSe2. The increase in photocurrent of Au nanorod/2D PtSe2 is remarkable and superior to that of functionalized TMDCs with metal nanoparticles [54][55][56]. However, the photocurrent decreased in 2D PtSe2 decorated with Au nanorods of concentrations higher than 10 nM.…”

Strain engineering of two‐dimensional materials: Methods, properties, and applications

“…Compared with the method of using flexible substrates to induce strain, using patterned substrates has a greater advantage that it keeps 2D materials in a constant local strained state, which is convenient for subsequent research. Moreover, the state of strain is closely related to the morphology of patterned substrates; thus, the strain and strain‐induced properties can be designed by changing the nanostructure patterns of substrates 64 …”