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

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.